CLIAMS:1. A compound of Formula I

Formula I
wherein, R1 and R2 are individually selected from a group comprising hydrogen, straight or branched chain C1-8 alkyl, straight or branched chain C1-8 alkenyl, straight or branched chain C1-8 alkynyl, aralkyl, substituted aralkyl, heteroaralkyl, substituted heteroaralkyl and wherein each of them may be optionally substituted,

or salts thereof.

2. A process of obtaining a compound of Formula I

Formula I
wherein, R1 and R2 are individually selected from a group comprising hydrogen, straight or branched chain C1-8 alkyl, straight or branched chain C1-8 alkenyl, straight or branched chain C1-8 alkynyl, aralkyl, substituted aralkyl, heteroaralkyl, substituted heteroaralkyl and wherein each of them may be optionally substituted,

said process comprising reacting a compound of Formula III with ester and base to obtain the compound of Formula I

Formula III
wherein R3 is selected from a group comprising, but not limited to, fluoro, chloro, bromo, iodo, methanesulfonyloxy, toluenesulfonyloxy, trifluoromethanesulfonyloxy, alkyloxy, aryloxy, arolkyl oxy, heteroaryloxy and wherein each of them may be optionally substituted.

3. The process as claimed in claim 2, wherein the ester is oxalic acid ester selected from a group comprising dimethyl oxalate, diethyl oxalate, dibenzyl oxalate, diisopropyl oxalate and di-tert-butyl oxalate or any combination thereof; and the base is selected from a group comprising sodium methoxide, sodium ethoxide, potassium t-butoxide, sodium hydride and 1,8-diazabicyclo[5.4.0]undec-7-ene or any combination thereof.

4. The process as claimed in claim 2, wherein the process is carried out at temperature ranging from about -20 ºC to about 100 ºC, preferably about 0 ºC to about 40 ºC and for a time period ranging from about 60 minutes to about 72 hours, preferably about 60 minutes to about 16 hours.

5. The process as claimed in claim 2, wherein the process further comprises isolation of the compound of Formula I; and wherein the isolation is carried out by acts selected from a group comprising quenching, filtration and extraction or any combination of acts in any order thereof.

6. A process for preparing 4,5-Dioxo-4,5-dihydro-1H-pyrrolo[2,3-f]quinoline-2,7,9-tricarboxylic acid and salts thereof, said process comprising steps of:
g. reacting a compound of Formula II with nitration mixture to obtain a compound of Formula III

Formula II Formula III

wherein, R3 is selected from a group comprising, but not limited to, fluoro, chloro, bromo, iodo, methanesulfonyloxy, toluenesulfonyloxy, trifluoromethanesulfonyloxy, alkyloxy, aryloxy, arolkyl oxy, heteroaryloxy and wherein each of them may be optionally substituted;
h. reacting the compound of Formula III with ester and base to obtain a compound of Formula I

Formula I
wherein, R1 and R2 are individually selected from a group comprising, but not limited to, hydrogen, straight or branched chain C1-8 alkyl, straight or branched chain C1-8 alkenyl, straight or branched chain C1-8 alkynyl, aralkyl, substituted aralkyl, heteroaralkyl, substituted heteroaralkyl and wherein each of them may be optionally substituted;

i. reacting the compound of Formula I with reducing agent to obtain a compound of Formula IV

Formula IV
wherein, R1 and R2 are individually selected from a group comprising, but not limited to, hydrogen, straight or branched chain C1-8 alkyl, straight or branched chain C1-8 alkenyl, straight or branched chain C1-8 alkynyl, aralkyl, substituted aralkyl, heteroaralkyl, substituted heteroaralkyl and wherein each of them may be optionally substituted;

j. converting the compound of Formula IV to a compound of Formula V in presence of coupling agent

Formula V
wherein, R1 and R2 are individually selected from a group comprising, but not limited to, hydrogen, straight or branched chain C1-8 alkyl, straight or branched chain C1-8 alkenyl, straight or branched chain C1-8 alkynyl, aralkyl, substituted aralkyl, heteroaralkyl, substituted heteroaralkyl and wherein each of them may be optionally substituted; and R4 is selected from group comprising, but not limited to, hydrogen, straight or branched chain C1-8 alkyl, straight or branched chain C1-8 alkenyl, straight or branched chain C1-8 alkynyl, aralkyl, substituted aralkyl, heteroaralkyl, substituted heteroaralkyl and wherein each of them may be optionally substituted;

k. reacting the compound of Formula V with oxidizing agent to obtain a compound of Formula VI

Formula VI
wherein R2 is selected from a group comprising, but not limited to, hydrogen, straight or branched chain C1-8 alkyl, straight or branched chain C1-8 alkenyl, straight or branched chain C1-8 alkynyl, aralkyl, substituted aralkyl, heteroaralkyl, substituted heteroaralkyl and wherein each of them may be optionally substituted; and R4 is selected from group comprising hydrogen, straight or branched chain C1-8 alkyl, straight or branched chain C1-8 alkenyl, straight or branched chain C1-8 alkynyl, aralkyl, substituted aralkyl, heteroaralkyl, substituted heteroaralkyl and wherein each of them may be optionally substituted;

and

l. hydrolyzing the compound of Formula VI to obtain 4,5-Dioxo-4,5-dihydro-1H-pyrrolo[2,3-f]quinoline-2,7,9-tricarboxylic acid and salts thereof.

7. The process as claimed in claim 6, wherein the salts are selected from a group comprising glucosamine, sodium, calcium and potassium or any combination thereof.

8. The process as claimed in claim 6, wherein the nitration mixture in step (a) is selected from a group comprising a mixture of nitric acid and sulphuric acid, calcium nitrate and acetic acid, and tert-butyl nitrite or any combination of mixtures thereof; the ester in step (b) is oxalic acid ester selected from a group comprising dimethyl oxalate, diethyl oxalate, Di-tert-butyl oxalate, and diisopropyl oxalate or any combination thereof; the base in step (b) is selected from a group comprising sodium methoxide, sodium ethoxide, potassium t-butoxide, sodium hydride and 1,8-diazabicyclo[5.4.0]undec-7-ene or any combination thereof; the reducing agent in step (c) is selected from a group comprising palladium, nickel, sodium dithionite, iron/hydrochloric acid, zinc/acetic acid and tin chloride/hydrochloric acid or any combination thereof; the coupling agent in step (d) is selected from a group comprising 4-oxo-pent-2-enedioic acid dimethyl ester, 4-oxo-pent-2-enedioic acid diethyl ester, 4-oxo-pent-2-enedioic acid diisopropyl ester and 4-oxo-pent-2-enedioic acid di-tert-butyl ester or any combination thereof; the oxidizing agent in step (e) is ceric ammonium nitrate; and the hydrolysis of step (f) is carried out in presence of base selected from a group comprising sodium carbonate, potassium carbonate, sodium hydroxide and lithium hydroxide or any combination thereof.

9. The process as claimed in claim 6, wherein the process is carried out in presence of solvent selected from a group comprising water, tetrahydrofuran, methanol, ethanol, acetonitrile, dichloromethane, tetrahydrofuran, dimethyl formamide and acetic acid or any combination thereof; and the step (d) is further carried out in presence of acid selected from a group comprising hydrochloric acid, trifluoroacetic acid and p-toluene sulfonic acid or any combination thereof.

10. The process as claimed in claim 6, wherein the process is carried out at temperature ranging from about -20 ºC to about 150 ºC, preferably about -10 ºC to about 100 ºC and for a time period ranging from about 30 minutes to about 72 hours, preferably about 30 minutes to about 24 hours.

11. The process as claimed in claim 6, wherein the steps (a), (b), (c), (d) (e) and (f) further comprise steps of precipitation or isolation or a combination thereof of the corresponding compound obtained; and wherein the isolation is carried out by acts selected from a group comprising addition of water, quenching, filtration and extraction or any combination of acts in any order thereof.

12. Use of compound of Formula I or salts thereof for preparation of 4,5-Dioxo-4,5-dihydro-1H-pyrrolo[2,3-f]quinoline-2,7,9-tricarboxylic acid and corresponding salts. ,TagSPECI:TECHNICAL FIELD
The present disclosure relates to compounds of Formula I and processes of obtaining the same. Said compounds of Formula I have numerous applications, more particularly, in the preparation of pyrroloquinoline quinone (PQQ) and its pharmaceutically acceptable salts. Said preparation involve the synthesis of PQQ and salts thereof via. compounds of Formula I as intermediates as represented below:


Formula I PQQ
Wherein, R1 and R2 is individually selected from a group comprising hydrogen, straight or branched chain C1-8 alkyl, straight or branched chain C1-8 alkenyl, straight or branched chain C1-8 alkynyl, aralkyl, substituted aralkyl, heteroaralkyl, substituted heteroaralkyl and each of them can be optionally substituted.

The said preparation of PQQ further employ minimum number of steps and have improved efficiency and scalability along with many other advantages.