DESC:FIELD OF THE INVENTION
The present invention relates to process for preparation of 1,1-dialkoxy-alkynol compounds of formula (I)

Formula (I)
wherein R1 and R2 are independently selected from C1 to C5 alkyl group; Y is hydrogen or a hydroxy protecting group selected from tert-butyl group, acetyl group, allyl group, benzyl group, trimethyl acetyl, trimethylsilyl (TMS), tert-butyldimethylsilyl group (TBDMS), tertiary butyldiphenyl silane (TBDPS), methyl-methoxy group (MOM), tetrahydropyranyl group (THP) or tetrahydropiperan n is 1 to 20 and m is 0 to 20.

BACKGROUND OF THE INVENTION
Pheromones are chemical/s produced as messengers that transmit information between individuals of the same species evoking physiological or behavioral responses in the individual receiving the signal. Pheromones of many species have been identified and are produced synthetically for using in insect pest management programs. Unlike pesticide, pheromones are required in less amount and are efficiently replacing toxic pesticides which are not only hazardous to environment, but also remains as residue in the crops which can be toxic and carcinogenic. Pheromones are an eco-sensitive way of dealing with pest infestation, controlling pest behaviour, and managing forests.

1,1-dialkoxy-alkynols compounds and derivatives thereof of general formula (I) are important intermediates in synthesis of many sex pheromones. For instance, said intermediate is used in synthesis of sex pheromones such as E-7, Z-9- dodecadienyl acetate, the pheromone of Lobesia botrana; pheromones of Spodoptera litura; pheromone of Earias vittella and the like.

Conventionally known processes for preparation of said 1,1-dialkoxy-alkynol compounds of formula (I) have disadvantages like complicated reaction steps, low yield of the desired product and are not suitable for large scale production.

Inventors of present invention have developed novel synthetic process for preparation of 1,1-dialkoxy-alkynol compounds of formula (I) in good yield.

OBJECT OF THE INVENTION
It is an object of the present invention to provide a process for producing 1,1-dialkoxy-alkynol compounds of formula (I), in high yield and purity.
It is another object of the present invention to provide a simple, cost-effective and industrially viable process for preparation of 1,1-dialkoxy-alkynol compounds of formula (I).
It is another object of the present invention to provide 1,1-dialkoxy-alkynol compounds of formula (I) useful for preparation of desired pheromone active ingredient.
It is yet another object of the present invention to provide a process for preparation of 1,1-dialkoxy-non-2-yn-9-ol compounds of formula (Ia), a key intermediate compound used for the synthesis of E-7, Z-9-dodecadienyl acetate, the pheromone of Lobesia botrana.

SUMMARY OF THE INVENTION
In an aspect of present invention, there is provided a process for preparation of 1,1-dialkoxy-alkynol compounds of formula (I)
Formula (I)
wherein R1 and R2 are independently selected from C1 to C5 alkyl group; Y is hydrogen or a hydroxy protecting group selected from tert-butyl group, acetyl group, allyl group, benzyl group, trimethyl acetyl, trimethylsilyl (TMS), tert-butyldimethylsilyl group (TBDMS), tertiary butyldiphenyl silyl (TBDPS), methyl-methoxy group (MOM), tetrahydropyranyl group (THP) or tetrahydropiperan, n is 1 to 20 and m is 0 to 20;
comprising the steps of
a) converting a compound of formula (II) to a compound of formula (III)

wherein R1, R2 and m have same meaning as above; and X1, X2 are independently selected from Cl, F, Br or I; and
b) reacting the compound of formula (III) with a compound of formula (IV) in presence of at least one polar aprotic solvent

wherein R1, R2, Y, m and n have same meaning as above; and X is selected from Cl, F, Br or I.
In an aspect of present invention, there is provided use of 1,1-dialkoxy-alkynol compounds of formula (I) prepared according to process of present invention, for synthesis of the desired pheromone active ingredient.
In an aspect of present invention, there is provided a process for preparation of 1,1-dialkoxy-non-2-yn-9-ol compounds of formula (Ia)

Formula (Ia)
wherein R1 and R2 are independently selected from C1 to C5 alkyl group; Y is hydrogen or a hydroxy protecting group selected from tert-butyl group, acetyl group, allyl group, benzyl group, trimethyl acetyl, trimethylsilyl (TMS), tert-butyldimethylsilyl group (TBDMS), tertiary butyldiphenyl silyl (TBDPS), methyl-methoxy group (MOM), tetrahydropyranyl group (THP) or tetrahydropiperan,
comprising
a) converting a compound of formula (IIa) to a compound of formula (IIIa)

wherein R1, R2 have same meaning as above; and X1, X2 are independently selected from Cl, F, Br or I; and
b) reacting the compound of formula (IIIa) with a compound of formula (IVa) in presence of at least one polar aprotic solvent

wherein R1, R2 and Y have same meaning as above; X is selected from Cl, F, Br or I.
In an aspect of present invention, there is provided use of 1,1-dialkoxy-non-2-yn-9-ol compounds of general formula (Ia) prepared according to process of present invention for synthesis of E-7, Z-9-dodecadienyl acetate, the pheromone of Lobesia botrana.

DETAILED DESCRIPTION OF THE INVENTION
Those skilled in art will be aware that invention described herein is subject to variations and modifications other than those specifically described. It is to be understood that the invention described herein includes all such variations and modifications. The invention also includes all such steps, features, compositions and methods referred to or indicated in this specification, individually or collectively, and any and all combinations of any two or more said steps or features.

Definitions:
The present disclosure now will be described hereinafter with reference to the accompanying examples, in which embodiments of the disclosure are shown. This description is not intended to be a detailed catalogue of all the different ways in which the disclosure may be implemented, or all the features that may be added to the instant disclosure. For example, features illustrated with respect to one embodiment may be incorporated into other embodiments, and features illustrated with respect to a particular embodiment may be deleted from that embodiment. Thus, the disclosure contemplates that in some embodiments of the disclosure, any feature or combination of features set forth herein can be excluded or omitted. In addition, numerous variations and additions to the various embodiments suggested herein will be apparent to those skilled in the art in light of the instant disclosure, which do not depart from the instant disclosure. Hence, the following descriptions are intended to illustrate some particular embodiments of the disclosure, and not to exhaustively specify all permutations, combinations and variations thereof.

It must be noted that, as used in this specification, the singular forms “a”, “an” and “the” include plural referents unless the content clearly dictates otherwise. The terms “preferred” and “preferably” refer to embodiments of the disclosure that may afford certain benefits, under certain circumstances.

As used herein, the terms “comprising”, “including”, “having”, “containing”, “involving”, and the like are to be understood to be open-ended i.e., to mean including but not limited to.

As used herein, the terms “monohalogenation” refer to selectively halogenating one hydroxy group of the diol compound of formula (V).

As used herein the examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms and iodine.

As used herein the (C1-C5) alkyl means a linear or branched chain alkyl having 1 to 6 carbon atoms. Examples of (C1-C5) alkyls include, but are not limited to, methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, isobutyl, tert-butyl, pentyl and the like.

As used herein, the terms “about” or “approximately” are inclusive of the stated value and means within an acceptable range of deviation for the particular value as determined by one of ordinary skill in the art, considering the measurement in question and the error associated with measurement of the particular quantity (i.e., the limitations of the measurement system). For example, “about” can mean within one or more standard deviations, or within ±10% or ±5% of the stated value.

Recitation of ranges of values are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. The endpoints of all ranges are included within the range and independently combinable. As used herein, all numerical values or numerical ranges include integers within such ranges and fractions of the values or the integers within ranges unless the context clearly indicates otherwise. Thus, for example, reference to a range of 90-100%, includes 91%, 92%, 93%, 94%, 95%, 95%, 97%, etc., as well as 91.1%, 91.2%, 91.3%, 91.4%, 91.5%, etc., 92.1%, 92.2%, 92.3%, 92.4%, 92.5%, etc., and so forth. All methods described herein can be performed in a suitable order unless otherwise indicated herein or otherwise clearly contradicted by context.

The use of any and all examples, or exemplary language (e.g., “such as”), is intended merely to better illustrate the disclosure and does not pose a limitation on the scope of the disclosure unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the disclosure as used herein.

While the disclosure has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made, and equivalents may be substituted for elements thereof without departing from the scope of the disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the essential scope thereof. Therefore, it is intended that the disclosure is not limited to the particular embodiment disclosed as the best mode contemplated for carrying out this disclosure, but that the disclosure will include all embodiments falling within the scope of the appended claims.

The expression of various quantities in terms of “%” or “% w/v” or “% w/w” means the percentage by weight of the total solution or composition unless otherwise specified.

Each of the aspects described above may have one or more embodiments. Each of the embodiments described hereinafter may apply to one or all of the aspects described hereinabove. These embodiments are intended to be read as being preferred features of one or all of the aspects described hereinabove. Each of the embodiments described hereinafter applies to each of the aspects described hereinabove individually.

In an aspect of present invention, there is provided a process for preparation of 1,1-dialkoxy-alkynol compounds of formula (I)

Formula (I)
wherein R1 and R2 are independently selected from C1 to C5 alkyl group; Y is hydrogen or a hydroxy protecting group selected from tert-butyl group, acetyl group, allyl group, benzyl group, trimethyl acetyl, trimethylsilyl (TMS), tert-butyldimethylsilyl group (TBDMS), tertiary butyldiphenyl silyne (TBDPS), methyl-methoxy group (MOM), tetrahydropyranyl group (THP) or tetrahydropiperan, n is 1 to 20 and m is 0 to 20.
In an embodiment, the process for preparation of 1,1-dialkoxy-alkynol compounds of formula (I) comprising
reacting a compound of formula (III) with a compound of formula (IV) in presence of at least one polar aprotic solvent to obtain a compound of formula (I).

In another embodiment, the process for preparation of 1,1-dialkoxy-alkynol compounds of formula (I) comprising the steps of
a) converting a compound of formula (II) to a compound of formula (III)

wherein R1, R2 and m have same meaning as above; and X1, X2 are independently selected from Cl, F, Br or I; and
b) reacting the compound of formula (III) with a compound of formula (IV) in presence of at least one polar aprotic solvent to obtain compound of formula (I)

wherein R1, R2, Y, m and n have same meaning as above; and X is selected from Cl, F, Br or I.
In an embodiment, the compound of formula (II) is prepared by conventionally known process.
In an embodiment, in the compound of formula (II) R1 and R2 are independently selected from C1 to C5 alkyl group; X1, X2 are independently selected from Cl, F, Br or I; and m is 0 to 20.
In an embodiment, the compound of formula (II) is a compound of formula (IIa), wherein R1 and R2 are independently selected from C1 to C5 alkyl group; X1, X2 are independently selected from Cl, F, Br or I.

Formula (IIa)
In an embodiment, the compound of formula (II) is 2,3- dihalo propionaldehyde dialkyl acetal represented by formula (IIa).
In an embodiment, in the compound of formula (II) R1 and R2 are independently methyl or ethyl group; X1, X2 are independently Br and m is 0 to 20.
In an embodiment, in the compound of formula (II) R1 and R2 are independently ethyl group; X1, X2 are independently Br and m is 0.
In an embodiment, the compound of formula (II) is 2,3- dibromo propionaldehyde diethyl acetal.
In an embodiment, the compound of formula (II) is converted to the compound of formula (III) by reacting the compound of formula (II) with a base.
In an embodiment the base used is selected from organic or inorganic base.
In an embodiment, the base used is inorganic base selected from, but not limited to, amides of alkali or alkaline earth metals, alkali metal alkoxides, alkali metal hydroxides, alkali metal carbonates, alkyl and aryl derivatives of the alkali metals or combinations thereof.
In an embodiment, the base used is inorganic base selected from amides of alkali or alkaline earth metals such as sodium amide, lithium amide; alkali metal alkoxides such as sodium methoxide, potassium methoxide, sodium tert-butoxide, potassium tert-butoxide and the like; alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, lithium hydroxide and the like; alkali metal carbonates such as potassium carbonate, potassium bicarbonate, sodium carbonate, sodium bicarbonate, lithium carbonate, lithium bicarbonate and the like; or alkyl and aryl derivatives of the alkali metals like n-butyl lithium.
In an embodiment, the base used is selected from alkali metal alkoxide, alkali metal hydroxide or combination thereof.
In an embodiment, the base used is alkali metal alkoxide selected from sodium methoxide, potassium methoxide, sodium tert-butoxide, potassium tert-butoxide and the like.
In an embodiment, the base used is alkali metal hydroxide selected from sodium hydroxide, potassium hydroxide, lithium hydroxide and the like.
In an embodiment, alkali metal alkoxide and alkali metal hydroxide both are used. Preferably, the molar ratio of alkali metal alkoxide and alkali metal hydroxide is in the range of 0.1 to 2:1.
In an embodiment, the amount of base used in step a) is in the range of about 1 to 10 moles with respect to compound of formula (II).
In an embodiment, the amount of base used in step a) is in the range of about 1 to 5 moles with respect to compound of formula (II).
In an embodiment, the compound of formula (II) is reacted with a base in presence of a solvent to obtain compound of formula (III).
In an embodiment, the solvent is selected from water; C1 to C5 alkyl alcohols, halogenated hydrocarbons; C6 to C10 alkanes; C6 to C10 cycloalkanes; benzene optionally substituted with alkyl group or combinations thereof.

In an embodiment, the solvent is selected from water, C1 to C5 alkyl alcohols (for example methanol, ethanol, n-propanol, n-butanol, n-pentanol), halogenated hydrocarbons (for example dichloromethane, dichloroethane, n-butyl chloride or n-pentyl chloride), C6 to C10 alkanes (for example n-hexane, hexanes, n-heptane, heptanes), C6 to C10 cycloalkanes (for example cyclohexane, methylcyclohexane, cycloheptane), benzene optionally substituted with alkyl group(for example benzene, toluene, xylene) or combinations thereof.

In an embodiment, the solvent is selected from water, C1 to C5 alkyl alcohols, C6 to C10 alkanes or mixture thereof.

In an embodiment, the solvent is ethanol.
In an embodiment, the solvent is n-hexane.
In an embodiment, the solvent is mixture of water, ethanol and n-hexane.
In an embodiment, the reaction in step a) is carried out at temperature ranging from about -10°C to 50°C.
In an embodiment, the compound of formula (III) obtained is a compound of formula (IIIa)

Formula (IIIa)
wherein R1 and R2 are independently selected from C1 to C5 alkyl group.
In an embodiment, the compound of formula (III) obtained is propiolaldehyde dialkyl acetal represented by formula (IIIa).
In an embodiment, in the compound of formula (III) R1 and R2 are independently selected from C1 to C5 alkyl group; and m is 0 to 20.
In an embodiment, in the compound of formula (III) R1 and R2 are independently methyl or ethyl group; and m is 0 to 20; is obtained in step a).
In an embodiment, in the compound of formula (III) R1 and R2 are independently ethyl group; and m is 0; is obtained in step a).
In an embodiment, the compound of formula (III) obtained in step a) is propiolaldehyde diethyl acetal.
In an embodiment the present process comprises reacting 2,3- dibromo propionaldehyde diethyl acetal with base in presence of suitable solvent at temperature ranging from about -10°C to 50°C to obtain propiolaldehyde diethyl acetal.
In an embodiment, the compound of formula (IV) is prepared by conventionally known process.
In an embodiment, in the compound of formula (IV) Y is hydrogen or a hydroxy protecting group selected from tert-butyl group, acetyl group, allyl group, benzyl group, trimethyl acetyl, trimethylsilyl (TMS), tert-butyldimethylsilyl group (TBDMS), tertiary butyldiphenyl silyl (TBDPS), methyl-methoxy group (MOM), tetrahydropyranyl group (THP) or tetrahydropiperan; X is Br; and n is 1 to 10.

In an embodiment, the compound of formula (IV) is a compound of formula (IVa)

Formula (IVa)
wherein, Y is hydrogen or a hydroxy protecting group selected from tert-butyl group, acetyl group, allyl group, benzyl group, trimethyl acetyl, trimethylsilyl (TMS), tert-butyldimethylsilyl group (TBDMS), tertiary butyldiphenyl silyl (TBDPS), methyl-methoxy group (MOM), tetrahydropyranyl group (THP) or tetrahydropiperan, and X is independently selected from Cl, F, Br or I.In an embodiment, the compound of formula (IV) is 1-tert-butoxy-4-bromo-hexane.
In another embodiment, the compound of formula (IV) is a compound of formula (IVb)

Formula (IVb)
wherein, Y is hydrogen or a hydroxy protecting group selected from tert-butyl group, acetyl group, allyl group, benzyl group, trimethyl acetyl, trimethylsilyl (TMS), tert-butyldimethylsilyl group (TBDMS), tertiary butyldiphenyl silyl (TBDPS), methyl-methoxy group (MOM), tetrahydropyranyl group (THP) or tetrahydropiperan; and X is independently selected from Cl, F, Br or I
In yet another embodiment, the compound of formula (IV) is 1-bromo-8-tert-butoxyoctane.
In another embodiment, the polar aprotic solvent used in step b) is selected from, but not limited to, the group comprising of dichloromethane, dimethylsulfoxide, tetrahydrofuran, 2-methyl tetrahydrofuran, ethylacetate, acetone, dimethylformamide, acetonitrile, propylene carbonate, N-methyl-2-pyrrolidone, hexamethylphosphoramide or mixture thereof.
In another embodiment, the polar aprotic solvent is selected from dimethylsulfoxide, tetrahydrofuran, 2-methyl tetrahydrofuran or mixture thereof.
In preferred embodiment, the polar aprotic solvent is dimethylsulfoxide. In another embodiment, polar aprotic solvent is a mixture of dimethylsulfoxide and 2-methyl tetrahydrofuran.
In one preferred embodiment, polar aprotic solvent is a mixture of dimethylsulfoxide and 2-methyl tetrahydrofuran in ratio of about 1: 9 to 9: 1.
In another embodiment, polar aprotic solvent is a mixture of dimethylsulfoxide and 2-methyl tetrahydrofuran in ratio of about 1: 1.
In another embodiment, polar aprotic solvent is a mixture of dimethylsulfoxide and 2-methyl tetrahydrofuran in ratio of about 1: 2.
In another embodiment, polar aprotic solvent is a mixture of dimethylsulfoxide and 2-methyl tetrahydrofuran in ratio of about 1: 3.
In another embodiment, polar aprotic solvent is a mixture of dimethylsulfoxide and 2-methyl tetrahydrofuran in ratio of about 1: 4.
In another embodiment, polar aprotic solvent is a mixture of dimethylsulfoxide and 2-methyl tetrahydrofuran in ratio of about 1: 5.
In another embodiment, polar aprotic solvent is a mixture of dimethylsulfoxide and tetrahydrofuran.
In yet another embodiment, polar aprotic solvent used is a mixture of dimethylsulfoxide and tetrahydrofuran in ratio of about 1: 9 to 9: 1.
In an embodiment, polar aprotic solvent used is a mixture of dimethylsulfoxide and tetrahydrofuran in ratio of about 1:1.
In an embodiment, polar aprotic solvent used is a mixture of dimethylsulfoxide and tetrahydrofuran in ratio of about 1:2.
In an embodiment, polar aprotic solvent used is a mixture of dimethylsulfoxide and tetrahydrofuran in ratio of about 1:3.
In another embodiment, polar aprotic solvent used is a mixture of dimethylsulfoxide and tetrahydrofuran in ratio of about 1:4.
In another embodiment, polar aprotic solvent used is a mixture of dimethylsulfoxide and tetrahydrofuran in ratio of about 1:5.
In an embodiment, the present invention provides a process for preparing a compound of formula (I) comprising,
reacting the compound of formula (III) with a compound of formula (IV) in presence of at least one polar aprotic solvent

wherein R1, R2, Y, m and n have same meaning as above; and X is selected from Cl, F, Br or I.
In another embodiment the present invention provides a process for preparing a compound of formula (I) comprising reacting the compound of formula (III) with a compound of formula (IV) in presence of at least one polar aprotic solvent and a second solvent.
In an embodiment, the second solvent used may be selected from, but not limited to, water, alcohols like methanol, ethanol, propanol, isopropanol, etc.; ketones like acetone, etc.; ester like ethyl acetate, isopropyl acetate, etc.; hydrocarbons like n-hexane, cyclohexane, heptane, etc.; aromatic hydrocarbons like toluene, xylene/s, etc. or mixtures thereof.
In an embodiment, the step b) of process is carried out in presence of a base, preferably a strong base.
In an embodiment, the base is selected from amides of alkali or alkaline earth metals or alkali metal hydrides.
In an embodiment, the base is selected from amides of alkali or alkaline earth metals such as sodium amide, lithium amide; lithium diisopropyl amide; or alkali metal hydrides like sodium hydride.
In a preferred embodiment, the base used is sodium hydride. In an embodiment, the sodium hydride used is in form of sodium hydride dispersion in mineral oil.
In an embodiment, the amount of base used in step b) is in the range of about 1 to 10 moles with respect to compound of formula (III).
In an embodiment, the amount of base used in step b) is in the range of about 1 to 5 moles with respect to compound of formula (III).
In an embodiment, the process of reacting the compound of formula (III) with a compound of formula (IV) is carried out at temperature below 100°C to obtain a compound of formula (I).
In another embodiment, the step b) of the process is carried out at temperature ranging from 10°C to 100°C.
In another embodiment, the step b) of the process is carried out at temperature ranging from 20°C to 80°C.
In yet another embodiment, the process according to the present invention provides a 1,1-dialkoxy-alkynol compounds of general formula (I) wherein R1 and R2 are independently selected from methyl or ethyl group; Y is hydrogen or a hydroxy protecting group selected from tert-butyl group, acetyl group, allyl group, benzyl group, trimethyl acetyl, trimethylsilyl (TMS), tert-butyldimethylsilyl group (TBDMS), tertiary butyldiphenyl silyl (TBDPS), methyl-methoxy group (MOM), tetrahydropyranyl group (THP) or tetrahydropiperan; n is 1 to 10 and m is 0 to 10.
In yet another embodiment, the process according to the present invention provides a 1,1-dialkoxy-alkynol compounds of general formula (I) wherein R1 and R2 are independently selected from methyl or ethyl group; Y is hydrogen or a hydroxy protecting group selected from tert-butyl group, acetyl group, allyl group, benzyl group, trimethyl acetyl, trimethylsilyl (TMS), tert-butyldimethylsilyl group (TBDMS), tertiary butyldiphenyl silyl (TBDPS), methyl-methoxy group (MOM), tetrahydropyranyl group (THP) or tetrahydropiperan; n is 6 and m is 0.
In an embodiment, the compound of formula (II) used in the present process can be prepared from acrolein using conventionally known methods. In one preferred embodiment, the compound of formula (II) can be prepared by reacting acrolein with bromine followed by reaction with triethyl orthoformate in presence of ethanol at temperature ranging from about -5°C to about 80°C.
Furthermore, the compound of formula (IV) used in the present process can be prepared converting a diol compound of formula (V) to compound of formula (IV)

wherein Y is hydrogen or a hydroxy protecting group selected from tert-butyl group, acetyl group, allyl group, benzyl group, trimethyl acetyl, trimethylsilyl (TMS), tert-butyldimethylsilyl group (TBDMS), tertiary butyldiphenyl silyl (TBDPS), methyl-methoxy group (MOM),tetrahydropyranyl group (THP) or tetrahydropiperan, X is Cl, F, Br or I; and n is 1 to 20.
The compound of formula (IV) can be obtained by monohalogenation of one hydroxyl group of diol compound of formula (V) by reaction with a halogenating agent.
The examples of halogenating agent are chlorine, hydrochloric acid, thionyl chloride, oxalyl chloride, phosphorus trichloride, phosphorus pentachloride, phosphorus oxychloride, carbon tetrachloride, bromine, hydrobromic acid, Phosphorus tribromide, Phosphorus pentabromide, phosphorus oxybromide, carbon tetrabromide and the likes.
The monohalogenation reaction to obtain the compound of formula (IV) is carried out in presence of organic solvent.
The organic solvent such as aromatic hydrocarbons (for example toluene, xylene etc.), alcohols (for example methanol, ethanol etc.), chlorinated solvents (for example dichloromethane, dichloroethane, chloroform, etc.) and the likes, are used.
In an embodiment the monohalogenation is carried out at temperature ranging from about 0°C to reflux temperature of the solvent used.
In an embodiment the compound of formula (IV) can be obtained by monobromination of one hydroxyl group of diol compound of formula (V) using aqueous hydrobromic acid in toluene at temperature ranging from 50°C to 120°C.
In an instance, the compound of formula (IV) is obtained by monohalogenation of one hydroxyl group and protecting other hydroxyl group of the diol compound of formula (V).
In an embodiment, the hydroxyl group of diol compound (V) is protected by tert-butyl group. Said protection may be carried out by reacting the compound obtained after monohalogenation of diol of compound of formula (V) with tert-butylating agents in presence of an acid catalyst at temperature ranging from about -5°C to 100°C.
The tert-butylating agents like methyl tert-butyl ether, isobutylene or tert-butyl alcohol can be used.
The acid catalyst such as sulfuric acid or ion exchange acid resin (for example amberlyst-15) can be used.
In an embodiment, the process according to the present invention provides a 1,1-dialkoxy-alkynol compound of formula (I) which can be represented by formula (Ia).

Formula (Ia)
wherein R1 and R2 are independently selected from C1 to C5 alkyl group; Y is hydrogen or a hydroxy protecting group selected from tert-butyl group, acetyl group, allyl group, benzyl group, trimethyl acetyl, trimethylsilyl (TMS), tert-butyldimethylsilyl group (TBDMS), tertiary butyldiphenyl silyl (TBDPS), methyl-methoxy group (MOM), tetrahydropyranyl group (THP) or tetrahydropiperan.
In yet another embodiment, the process according to the present invention provides a 1,1-dialkoxy-alkynol compounds of formula (I) which can be represented by general formula (Ib).

Formula (Ib)
wherein R1 and R2 are independently selected from C1 to C5 alkyl group; Y is hydrogen or a hydroxy protecting group selected from tert-butyl group, acetyl group, allyl group, benzyl group, trimethyl acetyl, trimethylsilyl (TMS), tert-butyldimethylsilyl group (TBDMS), tertiary butyldiphenyl silyl (TBDPS), methyl-methoxy group (MOM), tetrahydropyranyl group (THP) or tetrahydropiperan.
In an aspect of present invention, there is provided use of 1,1-dialkoxy-alkynol compounds of general formula (I) or compound of formula (Ia) or compound of formula (Ib) prepared according to process of present invention for synthesis of the desired pheromone active ingredient.
In an embodiment, 1,1-dialkoxy-alkynol compound of formula (I) prepared according to process of present invention is used for synthesis of E-7, Z-9- dodecadienyl acetate, the pheromone of Lobesia botrana; and the like.
In an aspect of present invention, there is provided a process for preparation of 1,1-dialkoxy-non-2-yn-9-ol compounds of formula (Ia)

Formula (Ia)
wherein R1 and R2 are independently selected from C1 to C5 alkyl group; Y is hydrogen or a hydroxy protecting group selected from tert-butyl group, acetyl group, allyl group, benzyl group, trimethyl acetyl, trimethylsilyl (TMS), tert-butyldimethylsilyl group (TBDMS), tertiary butyldiphenyl silane (TBDPS), methyl-methoxy group (MOM), tetrahydropyranyl group (THP) or tetrahydropiperan,
comprising
a) converting a compound of formula (IIa) to a compound of formula (IIIa)

wherein R1, R2 have same meaning as above; and X1, X2 are independently selected from Cl, F, Br or I; and
b) reacting the compound of formula (IIIa) with a compound of formula (IVa) in presence of at least one polar aprotic solvent to obtain the compound of formula (Ia)

wherein R1, R2 and Y have same meaning as above; X is selected from Cl, F, Br or I
In an embodiment, in the compound of formula (IIa) R1 and R2 are independently selected from C1 to C5 alkyl group; and X1, X2 are independently selected from Cl, F, Br or I
In an embodiment, in the compound of formula (IIa) R1 and R2 are independently methyl or ethyl group; and X1, X2 are independently Br.
In an embodiment, in the compound of formula (IIa) R1 and R2 are independently ethyl group; and X1, X2 are independently Br.
In an embodiment, the compound of formula (IIa) is 2,3- dibromo propionaldehyde diethyl acetal.
In an embodiment, the compound of formula (IIa) is prepared by reacting acrolein with bromine followed by reaction with triethyl orthoformate in presence of ethanol at temperature ranging from about -5°C to about 80°C.
In an embodiment, the step a) of converting the compound of formula (IIa) to compound of formula (IIIa) comprises reacting the compound of formula (IIa) with a base in presence of a solvent.
In an embodiment, the base is selected from organic or inorganic base.
In an embodiment, the base used is inorganic base selected from, but not limited to, amides of alkali or alkaline earth metals, alkali metal alkoxides, alkali metal hydroxides, alkali metal carbonates, alkyl and aryl derivatives of the alkali metals or combinations thereof.
In an embodiment, the base is inorganic base selected from amides of alkali or alkaline earth metals such as sodium amide, lithium amide; alkali metal alkoxides such as sodium methoxide, potassium methoxide, sodium tert-butoxide, potassium tert-butoxide and the like; alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, lithium hydroxide and the like; alkali metal carbonates such as potassium carbonate, potassium bicarbonate, sodium carbonate, sodium bicarbonate, lithium carbonate, lithium bicarbonate and the like; or alkyl and aryl derivatives of the alkali metals like n-butyl lithium.
In preferred embodiment, the base is alkali metal alkoxides such as sodium methoxide, potassium methoxide, sodium tert-butoxide, potassium tert-butoxide and the like.
In another embodiment, in step a) alkali metal alkoxide and alkali metal hydroxide both are used. Preferably, the molar ratio of alkali metal alkoxide and alkali metal hydroxide is in the range of 0.1 to 2:1.
In an embodiment, the solvent used in step a) is organic solvent selected from such as C1 to C5 alkyl alcohols (for example n-propanol, n-butanol, n-pentanol), C1 to C5 halogenated hydrocarbons (for example dichloromethane, dichloroethane, ), C6 to C10 linear or cyclic aliphatic hydrocarbons wherein cyclic hydrocarbons optionally substituted with up to 2 substituents independently selected from C1-C2 alkyl (for example n-hexane, hexanes, n-heptane, heptanes, cyclohexane, methylcyclohexane, cycloheptane), and aromatic hydrocarbons (for example benzene, toluene, xylene).

In an embodiment, the solvent used in step a) is n-hexane.
In an embodiment, the step a) of converting the compound of formula (IIa) to compound of formula (IIIa) comprises reacting the compound of formula (IIa) with alkali metal alkoxide in presence of hexane as a solvent.
In another embodiment, the step a) of converting the compound of formula (IIa) to compound of formula (IIIa) comprises steps of reacting the compound of formula (IIa) with alkali hydroxide; followed by reaction with alkali metal alkoxide.
In an embodiment, step a) reaction is carried out at temperature ranging from -5°C to 40°C.In an embodiment, process of converting the compound of formula (IIa) to compound of formula (IIIa) is carried out at temperature ranging from -5°C to 50°C.
In an embodiment, the compound of formula (IIIa) wherein R1 and R2 are independently methyl or ethyl group; is obtained.
In an embodiment, the compound of formula (IIIa) obtained is propiolaldehyde diethyl acetal.
In an embodiment, the compound of formula (IIIa) is further reacted with compound of formula (IVa) in presence of at least one polar aprotic solvent.
In an embodiment, the compound of formula (IVa) is prepared by conventionally known process.
In an embodiment, the compound of formula (IVa) is, wherein Y is hydrogen or a hydroxy protecting group selected from tert-butyl group, acetyl group, allyl group, benzyl group, trimethyl acetyl, trimethylsilyl (TMS), tert-butyldimethylsilyl group (TBDMS), tertiary butyldiphenyl silyl (TBDPS), methyl-methoxy group (MOM), tetrahydropyranyl group (THP) or tetrahydropiperan; and X is Br.
In an embodiment, the compound of formula (IVa) is 1-tert-butoxy-6-bromo-hexane.
In another embodiment, the polar aprotic solvent in step b) is selected from, but not limited to, the group comprising of dichloromethane, dimethylsulfoxide, tetrahydrofuran, 2-methyl tetrahydrofuran, ethylacetate, acetone, dimethylformamide, acetonitrile, propylene carbonate, N-methyl-2-pyrrolidone, hexamethylphosphoramide or mixture thereof.
In another embodiment, polar aprotic solvent is dimethylsulfoxide.
In another embodiment, the polar aprotic solvent is mixture of dimethylsulfoxide and 2-methyl tetrahydrofuran.In an embodiment, the polar aprotic solvent is a mixture of dimethylsulfoxide and 2-methyl tetrahydrofuran in ratio of about 1: 9 to 9: 1.
In another embodiment, polar aprotic solvent is mixture ofdimethylsulfoxide and tetrahydrofuran.
In another embodiment, the polar aprotic solvent is mixture of dimethylsulfoxide and tetrahydrofuran in ratio of about 1: 9 to 9: 1.
In another embodiment, the step b) of the process is carried out in presence of a second solvent.
In an embodiment, the compound of formula (IIIa) is reacted with compound of formula (IVa) in presence of at least one polar aprotic solvent and a second solvent to obtain a compound of formula (Ia).
In an embodiment, the second solvent is selected from water, alcohols; ketones; esters; hydrocarbons or mixtures thereof.
In an embodiment, the second solvent is selected from, but not limited to, water, alcohols like methanol, ethanol, propanol, isopropanol, etc.; ketones like acetone, etc.; ester like ethyl acetate, isopropyl acetate, etc.; hydrocarbons like n-hexane, cyclohexane, heptane, etc.; aromatic hydrocarbons like toluene, xylene/s, etc. or mixtures thereof.
In an embodiment, a mixture of dimethylsulfoxide and toluene in ratio of about 1: 9 to about 9: 1, is used in step b).In an embodiment, step b) is carried out in presence of strong base.
In an embodiment, the strong base used in step b) used is selected from amides of alkali or alkaline earth metals such as sodium amide, lithium amide; lithium diisopropyl amide; or alkali metal hydrides like sodium hydride.
In a preferred embodiment, the base used is sodium hydride. The sodium hydride used is in form of sodium hydride dispersion in mineral oil.
In an embodiment, the amount of the base used in step b) is in the range of about 1 to 10 moles with respect to compound of formula (IIIa).
In an embodiment, the amount of the base used in step b) is in the range of about 1 to 5 moles with respect to compound of formula (IIIa).
In another embodiment, the step b) of the process is carried out at temperature below 100°C.
In another embodiment, the step b) of the process is carried out at temperature ranging from 10°C to 100°C.
In another embodiment, the step b) of the process is carried out at temperature ranging from 20°C to 80°C.
In yet another embodiment, the process according to the present invention provides a 1,1-dialkoxy-alkynol compounds of formula (Ia) wherein R1 and R2 are independently selected from methyl or ethyl group; and Y is hydrogen or a hydroxy protecting group selected from tert-butyl group, acetyl group, allyl group, benzyl group, trimethyl acetyl, trimethylsilyl(TMS), tert-butyldimethylsilyl group (TBDMS), tertiary butyldiphenyl silyl (TBDPS), methyl-methoxy group (MOM), tetrahydropyranyl group (THP) or tetrahydropiperan.
In yet another embodiment, the compound of formula (Ia) obtained is 9-(1,1-Dimethylethoxy)-1,1-diethoxy-2-nonyne; a key intermediate compound for synthesis of E-7, Z-9-dodecadienyl acetate, the pheromone of Lobesia Botrana.
In an embodiment, the process for preparation of 9-(1,1-Dimethylethoxy)-1,1-diethoxy-2-nonyne of formula (Ib)

Formula (Ib)
comprising
i) preparing 2,3-dibromo propionaldehyde diethyl acetal of formula (IIb) by reacting acrolein with bromine and triethyl orthoformate in presence of ethanol at temperature ranging from about -5°C to about 80°C;

ii) reacting 2, 3-dibromo propionaldehyde diethyl acetal (formula (IIb)) with a base in presence of a solvent to obtain propiolaldehyde diethyl acetal (formula (IIIb)); and

iii) reacting propiolaldehyde diethyl acetal formula (IIIb) with 1-tert-butoxy-6-bromo-hexane formula (IVb) in presence of sodium hydride and at least one polar aprotic solvent to obtain 9-(1,1-Dimethylethoxy)-1,1-diethoxy-2-nonyne of formula (Ib).


In an embodiment, the base used in step ii) is an inorganic base selected from amides of alkali or alkaline earth metals, alkali metal alkoxides, alkali metal hydroxides, alkali metal carbonates, alkyl and aryl derivatives of the alkali metals or combinations thereof.
The amides of alkali or alkaline earth metals such as sodium amide, lithium amide; the alkali metal alkoxides such as sodium methoxide, potassium methoxide, sodium tert-butoxide, potassium tert-butoxide and the like; or the strong bases like n-butyl lithium are used.
In an embodiment, the solvent used in step ii) is selected from C6 to C10 alkanes; C6 to C10 cycloalkanes; benzene optionally substituted with alkyl group; or mixture thereof.
The solvent used is selected from C6 to C10 alkanes (for example n-hexane, hexanes, n-heptane, heptanes), C6 to C10 cycloalkanes optionally substituted with up to 2 substituents independently selected from C1-C2 alkyl (for example cyclohexane, methylcyclohexane, cycloheptane), and benzene optionally substituted with up to 3 groups independently selected from C1-C2 alkyl (for example benzene, toluene, xylene).
In another embodiment, the solvent used in step ii) is water, ethanol, hexane or combination thereof.

In an embodiment, the solvent used in step ii) is n-hexane.In an embodiment, the step ii) reaction is carried out at temperature ranging from -5°C to 40°C.
In another embodiment, polar aprotic solvent used is selected from, but not limited to, the group comprising of dichloromethane, dimethylsulfoxide, tetrahydrofuran, 2-methyl tetrahydrofuran, ethylacetate, acetone, dimethylformamide, acetonitrile, propylene carbonate, N-methyl-2-pyrrolidone, hexamethylphosphoramide or mixture thereof.
In an embodiment, in step iii) 1-tert-butoxy-6-bromo-hexane of formula (IVb) is prepared by monobrominating hexane 1,6-diol followed by protecting hydroxy group with a tert-butyl group.
In an aspect of present invention, there is provided use of 1,1-dialkoxy-non-2-yn-9-ol compounds of formula (Ia) or formula (Ib) prepared according to process of present invention for synthesis of E-7, Z-9-dodecadienyl acetate, the pheromone of Lobesia Botrana.
In an embodiment, there is provided E-7, Z-9-dodecadienyl acetate prepared using 1,1-dialkoxy-alkynol compounds of formula (Ia) or formula (Ib) synthesised according to the present process.
In an embodiment, the present invention provides 1,1-dialkoxy-alkynol compounds of formula (Ia) or formula (Ib) used for the synthesis of E-7, Z-9-dodecadienyl acetate.
ADVANTAGES OF THE PRESENT INVENTION
1. The present invention provides a process for preparation of 1,1-dialkoxy-alkynol compound of formula (I), in good yield and high purity.
2. The present invention provides a simple, cost-effective and industrially viable process for preparation of 1,1-dialkoxy-alkynol compounds of formula (I).
3. The present invention provides a simple, cost-effective and industrially viable process for preparation of 9-(1,1-Dimethylethoxy)-1,1-diethoxy-2-nonyne in high purity.
EXAMPLES
The following examples are presented to provide what is believed to be the most useful and readily understood description of procedures and conceptual aspects of this invention. The examples provided below are merely illustrative of the invention and are not intended to limit the same to disclosed embodiments. Variations and changes obvious to one skilled in the art are intended to be within the scope and nature of the invention.
Analytical methods:
Gas Chromatography (GC): Parameters Description
Column ZB WAX, 30-m×0.25 mm×0.5 µm
Column oven temperature Programming Initial 60.0 ºC - 2.0 Min. Hold, 10 ºC/Min. - 220 ºC – 20.0 Min. Hold
Total Run Time 38.0 min
Injection port temperature 225 ºC
Injection Volume 1 µL
Split Ratio 1:10
Detector temperature 280 ºC
Column Flow 1.5 mL/Min
Purge Flow 2.0 mL/Min.

Example 1: Preparation of 2,3- dibromo propionaldehyde diethyl acetal [Compound of formula (IIb)]
In a round bottom flask, acrolein (330.0 g, 5.88 mole) was charged, bromine ( 302.01ml,, 5.88 mole) was added dropwise at 0-5°C and the mixture was stirred for 2 hours. A solution of triethyl orthoformate ( 1057.23 ml, 6.29 moles) in 760ml absolute ethanol was added to the mixture and the mixture was warmed up to 45°C and, stirred for 3 hours. After completion of reaction, ethyl formate, ethanol, and triethyl orthoformate were removed from the reaction mixture by distillation to get 2,3- dibromo propionaldehyde diethyl acetal (1194.0g) as brown liquid (Yield: 70% and Purity :91.65%).
Example 2: Preparation of propiolaldehyde diethyl acetal (Compound of formula (IIIb))
In a round bottom flask a slurry of potassium t-butoxide (291 g, 2.58 mol) in hexane (2.0L) was prepared and 2,3-dibromo propionaldehyde diethyl acetal (250g, 0.86 mol) was added to the slurry at 0°C. The mixture was stirred for 6 hours at 30°C. After the completion of reaction, the suspension was cooled to 0°C and water was added. The separated organic layer was distilled off to get propionaldehyde diethyl acetal (53.12g) as colourless oil (Yield: 54% and Purity: 97.88 %).
Example 2A: Preparation of propiolaldehyde diethyl acetal (Compound of formula (IIIb))
To stirred solution of ethanol (249.68ml), water (63ml) and potassium hydroxide (72.5g) was added 2,3-dibromo propionaldehyde diethyl acetal (263g) at room temperature. The mixture was then stirred at 30°C -40°C for 4 to 5 hours. To the reaction mixture was then added hexane (756.42ml) and water (250ml). Layers were separated and to the organic layer was added potassium t-butoxide (145 g) at 10°C- 15°C. The mixture was then heated to 35°C to 40°C and stirred till completion of reaction. To mixture was then added water and layers were separated. The organic layer was distilled off to get propionaldehyde diethyl acetal (75.6 g) (Yield: 65.9% and Purity: 96.24%).
Example 3: Preparation of 1-tert-butoxy-6-bromo-hexane (Compound of formula (IVb))
Step 1: Monobromination of 1,6-hexanediol
To a stirred solution of 1,6-hexanediol (200 g, 1.69 mol) dissolved in toluene (1400ml) was added 47% aqueous HBr (97.65ml, 0.84 mol) dropwise at reflux temperature. Dean Stark apparatus was used to facilitate the removal of water that get formed during the reaction. The reaction mixture was refluxed till no more water is formed, the mixture was then cooled to room temperature and layers were separated. The lower layer containing unreacted 1,6-hexanediol was removed and the organic layer comprising product was washed with water and then toluene was distilled off to get 6-bromohexan-1-ol (125.8g). Yield:76.27% having dibromo hexane < 4 %.
Step 2: Preparation of 1-tert-butoxy-6-bromo-hexane using tert-butyl-methyl-ether
To a solution of 6-bromo-hexan-1-ol (300g,1.65mol) and tert-butyl-methyl-ether (2548ml) was added concentrated sulfuric acid (88.52ml) dropwise under cooling. The reaction mixture was maintained at 35- 40°C and stirred for 8 hours. The reaction mixture was then diluted with water. The organic layer was separated, washed with saturated sodium bicarbonate solution (20g, 250ml water), dried and the solvent was removed under reduced pressure to obtain crude 1-tert butoxy-6-bromo-hexane (200g) as yellow oil. (Yield: 72.99% and Purity: 98.3% purity).
Example 4: Preparation of 1-tert-butoxy-6-bromo-hexane using isobutylene gas
To a solution of 6-bromo-hexan-1-ol (300g,1.65mol) and toluene (450ml) was added 10g of amberlyst 15 at 25-30°C followed by purging isobutylene gas (approximately 2 mol) . The reaction mixture was maintained till completion of reaction. The catalyst used was then recovered by filtration and to the filtrate was added 5% sodium bicarbonate solution. The mixture was stirred, organic layer was separated and the solvent was removed under reduced pressure to obtain crude 1-tert butoxy-6-bromo-hexane (106g) as yellow oil which was purified by passing through a filtration column. (Yield: 81%).
Example 5: Process for preparation of 9-(1,1-Dimethylethoxy)--1,1-diethoxy-2-nonyne
In a 500 ml three neck round bottom flask, sodium hydride (62.5g, 1.75 mol) under nitrogen atmosphere, was added mixture of 2-methyl tetrahydrofuran (539ml) and dimethylsulfoxide (270ml). To this mixture was slowly added propiolaldehyde diethyl acetal (90g,0.70 mol in 179.74ml 2-methyl tetrahydrofuran), stirred and heated to 50°C, followed by addition of 1-tert-butoxy-6-bromohexane (183.2g 0.77 mol; in 359.48ml 2-methyl tetrahydrofuran). The mixture was stirred for 1.5-2hrs and cooled to 20-25 °C, the reaction mass was then quenched with saturated ammonium chloride solution (1350ml). The aqueous and organic layers were then separated, and the organic layer was concentrated to obtain 9-(1,1-dimethylethoxy)--1,1-diethoxy-2-nonyne (167.7g), analysed by GC with isolated yield: 84% and 96.77% purity.
Example 6: Process for preparation of 9-(1,1-Dimethylethoxy)--1,1-diethoxy-2-nonyne
In a 500 ml three neck round bottom flask, sodium hydride (3.9g, 0.097 mol) under nitrogen atmosphere, was added dimethylsulfoxide (36.36ml). To this mixture was slowly added propiolaldehyde diethyl acetal (5g, 0.039 mol) solution in dimethylsulfoxide (18.18ml) and the mixture was stirred and heated to 50°C. 1-tert-butoxy-6-bromohexane (9.53g, 0.039 mol) solution in dimethylsulfoxide (18.18ml) was added to the reaction mixture and stirred for 2-3hrs and then cooled to 20-25 °C. The mass was quenched with saturated ammonium chloride solution (100ml). The separated organic layer was then concentrated on rota-evaporator and the concentrated mass was then purified by column chromatography to get 9-(1,1-dimethylethoxy)-1,1-diethoxy-2-nonyne (0.5g).

Example 7: Process for preparation of 9-(1,1-dimethylethoxy)--1,1-diethoxy-2-nonyne
To sodium hydride (78g, 1.95 mol) under nitrogen atmosphere, was added a mixture of toluene (530.5ml) and dimethylsulfoxide (281.8ml). Propiolaldehyde diethyl acetal (100g,0.78 mol) in toluene (230.68ml) was added to this mixture and the mixture was stirred and heated to 50°C, followed by addition of 1-tert-butoxy-6-bromohexane (192.64, 0.78 mol) in toluene (230.68ml). The mixture was stirred for 1.5-2hrs and cooled to 20-25 °C, the reaction mass was then quenched with saturated ammonium chloride solution (1350ml). The separated organic layer was concentrated, and the concentrated mass is purified by high vacuum distillation to obtain 9-(1,1-dimethylethoxy)--1,1-diethoxy-2-nonyne (180g), analysed by GC with isolated yield: 81.09% and 95.25% purity.
,CLAIMS:
1. A process for preparation of 1,1-dialkoxy-alkynol compounds of formula (I)

Formula (I)
wherein R1 and R2 are independently selected from C1 to C5 alkyl group; Y is hydrogen or a hydroxy protecting group selected from tert-butyl group, acetyl group, allyl group, benzyl group, trimethyl acetyl, trimethylsilyl (TMS), tert-butyldimethylsilyl group (TBDMS), tertiary butyldiphenyl silyl (TBDPS), methyl-methoxy group (MOM), tetrahydropyranyl group (THP) or tetrahydropiperan, n is 1 to 20 and m is 0 to 20;
comprising the steps of
a) converting a compound of formula (II) to a compound of formula (III)

wherein R1, R2 and m have same meaning as above; and X1, X2 are independently selected from Cl, F, Br or I; and
b) reacting the compound of formula (III) with a compound of formula (IV) in presence of at least one polar aprotic solvent

wherein R1, R2, Y, m and n have same meaning as above; and X is selected from Cl, F, Br or I.

2. The process as claimed in claim 1, wherein said compound of formula (II) is 2,3- dihalo propionaldehyde dialkyl acetal represented by formula (IIa).

Formula (IIa)

3. The process as claimed in claim 1, wherein said step a) comprises reacting the compound of formula (II) with a base in presence of a solvent.

4. The process as claimed in claim 3, wherein the base is an inorganic base selected from amides of alkali or alkaline earth metals, alkali metal alkoxides, alkali metal hydroxides, alkali metal carbonates, alkyl and aryl derivatives of the alkali metals or combinations thereof.

5. The process as claimed in claim 3, wherein the solvent is selected from water, C1 to C5 alkyl alcohols, halogenated hydrocarbons, C6 to C10 alkanes, C6 to C10 cycloalkanes, benzene optionally substituted with alkyl group; or mixtures thereof.

6. The process as claimed in claim 1, wherein said step a) is carried out at temperature ranging from about -10°C to 50°C.

7. The process as claimed in claim 1, wherein the compound of formula (III) is propiolaldehyde dialkyl acetal represented by formula (IIIa)

Formula (IIIa)
8. The process as claimed in claim 1, wherein the compound of formula (IV) is represented by formula (IVa)

Formula (IVa)
wherein, Y is hydrogen or a hydroxy protecting group selected from tert-butyl group, acetyl group, allyl group, benzyl group, trimethyl acetyl, trimethylsilyl (TMS), tert-butyldimethylsilyl group (TBDMS), tertiary butyldiphenyl silyl (TBDPS), methyl-methoxy group (MOM), tetrahydropyranyl group (THP) or tetrahydropiperan, and X is independently selected from Cl, F, Br or I.

9. The process as claimed in claim 1, wherein the compound of formula (IV) is represented by formula (IVb)

Formula (IVb)
wherein, Y is hydrogen or a hydroxy protecting group selected from tert-butyl group, acetyl group, allyl group, benzyl group, trimethyl acetyl, trimethylsilyl (TMS), tert-butyldimethylsilyl group (TBDMS), tertiary butyldiphenyl silyl (TBDPS), methyl-methoxy group (MOM), tetrahydropyranyl group (THP) or tetrahydropiperan; and X is independently selected from Cl, F, Br or I.

10. The process as claimed in claim 1, wherein the polar aprotic solvent is selected from a group comprising of dichloromethane, dimethylsulfoxide, tetrahydrofuran, 2-methyl tetrahydrofuran, ethylacetate, acetone, dimethylformamide, acetonitrile, propylene carbonate, N-methyl-2-pyrrolidone, hexamethylphosphoramide or mixture thereof.

11. The process as claimed in claim 1, wherein said step b) is carried out in presence of a base.

12. The process as claimed in claim 11, wherein the base is selected from amides of alkali or alkaline earth metals or alkali metal hydrides.

13. The process as claimed in claim 1, wherein the step b) is carried out at temperature ranging from 10°C to 100°C.

14. The process as claimed in claim 1, wherein the step b) is carried out in presence of a second solvent.

15. The process as claimed in claim 14, wherein the second solvent is selected from water, alcohols; ketones; esters; hydrocarbons or mixtures thereof.

16. A process for preparation of 9-(1,1-Dimethylethoxy)-1,1-diethoxy-2-nonyne of formula (Ib)

Formula (Ib)
comprising
i) preparing 2,3-dibromo propionaldehyde diethyl acetal by reacting acrolein with bromine and triethyl orthoformate in presence of ethanol at temperature ranging from about -5°C to about 80°C;
ii) reacting 2, 3-dibromo propionaldehyde diethyl acetal with a base in presence of a solvent to obtain propiolaldehyde diethyl acetal; and
iii) reacting propiolaldehyde diethyl acetal with 1-tert-butoxy-6-bromo-hexane in presence of sodium hydride and at least one polar aprotic solvent to obtain 9-(1,1-Dimethylethoxy)-1,1-diethoxy-2-nonyne of formula (Ib).

17. The process as claimed in claim 16, wherein 1-tert-butoxy-6-bromo-hexane is prepared by monobrominating hexane 1,6-diol followed by protecting hydroxy group with a tert-butyl group.