PROCESS FOR THE PREPARATION OF VILAZODONE OR ITS
PHARMACEUTICALLYACCEPTABLE SALTS
Field of the Invention
The present invention relates to a process for the preparation of vilazodone or its
pharmaceutically acceptable salts. The present invention further provides a crystalline
form of vilazodone free base.
Background of the Invention
Vilazodone is chemically described as 5-{4-[4-(5-cyano-lH-indol-3-
yl)butyl]piperazin- 1-yl} -1-benzofuran-2-carboxamide of Formula I .
FORMULA I
Vilazodone is indicated for the treatment of a major depressive disorder (MDD).
Processes for the preparation of vilazodone are described in U.S. Patent Nos.
5,532,241 and 7,799,916, and European Patent No. EP 0 648 767.
Summary of the Invention
The present invention relates to a process for the preparation of vilazodone or its
pharmaceutically acceptable salts.
Brief Description of the Drawings
Figure 1 depicts the X-Ray Powder Diffraction Pattern (XRPD) of the vilazodone free
base obtained according to Example 1.
Figure 1A provides the table of values for the XRPD pattern depicted in Figure 1.
Figure 2 depicts the X-Ray Powder Diffraction Pattern (XRPD) of the vilazodone free
base obtained according to Example 3.
Figure 2A provides the table of values for the XRPD pattern depicted in Figure 2.
Detailed Description of the Invention
An aspect of the present invention provides a process for the preparation of 5-{4-
[4-(5-cyano- 1H-indol-3-yl)butyl]piperazin- 1-yl} -1-benzofuran-2-carboxamide of Formula
I
FORMULA I
or its pharmaceutically acceptable salts which comprises:
a) reacting 3-(4-chlorobutyl)-lH-indole-5-carbonitrile of Formula II
FORMULA II
with 5-(piperazin-l-yl)-l-benzofuran-2-carboxamide of Formula III
FORMULA III
in the presence of a base and solvent;
b) isolating the compound of Formula I from the reaction mixture thereof; and
c) optionally converting the compound of Formula I to its pharmaceutically
acceptable salts.
Treatment of the compound of Formula II and the compound of Formula III may
be carried out in the presence of a base and solvent. The solvent may be selected from a
group consisting of water, organic solvent, or a mixture thereof. Suitable organic solvents
may be selected from a group consisting of alcohol, ketone, nitrile, amide, aromatic or
aliphatic hydrocarbon, or dimethyl sulfoxide. Suitable alcoholic solvents may include
methanol, 2-propanol, or 1-propanol. Suitable nitrile solvents may include acetonitrile.
Suitable amide solvents may include N-methylpyrrolidone or dimethylformamide.
Suitable ketonic solvents may include acetone or methyl isobutyl ketone. Suitable
aromatic hydrocarbon solvents may include toluene. Preferable solvents may include
water alone or in combination with 2-propanol, 1-propanol, dimethylformamide, or
toluene. The treatment of the compound of Formula II and the compound of Formula III
may be carried out in the presence of only water without using any other solvent.
The base may be selected from a group consisting of organic base or inorganic
base. A suitable organic base may include triethylamine, diisopropylamine,
diisopropylethylamine, 4-dimethylaminopyridine, pyrollidine, or N-methyl morpholine. A
preferable organic base includes triethylamine. A suitable inorganic base may include
hydroxides or carbonates and bicarbonates of alkali or alkaline metal. Suitable carbonates
or bicarbonates of alkali or alkaline metal may include sodium carbonate, potassium
carbonate, magnesium carbonate, sodium bicarbonate, or potassium bicarbonate. A
preferable inorganic base includes potassium carbonate. Treatment of the compound of
Formula II and the compound of Formula III may be carried out in the presence of alkali
metal halides, for example, sodium iodide.
The treatment of the compound of Formula II and the compound of Formula III
may be carried out a temperature of about 5°C to about 110°C, preferably at about 15°C to
about 90°C. The treatment of the compound of Formula II and the compound of Formula
III may be carried for about 2 hours to about 35 hours, preferably for about 5 hours to
about 30 hours.
The vilazodone free base of Formula I prepared by the present invention may be
converted to its pharmaceutically acceptable salt before isolation. The vilazodone free
base of Formula I may be isolated by filtration, concentration, precipitation, cooling,
centrifugation, decantation, or a combination thereof.
Vilazodone free base obtained by the present invention can be converted to its
pharmaceutically acceptable salt, for example hydrochloric acid salt, by any of the method
known in the art. The vilazodone hydrochloride salt may be isolated by filtration,
decantation, or a combination thereof.
Another aspect of the present invention provides a crystalline form of vilazodone
free base.
Crystalline form of vilazodone free base has substantially the same XRPD (X-Ray
Powder Diffraction Pattern) pattern as depicted in Figure 1 or Figure 2. The crystalline
form of vilazodone free base is characterized by an XRPD pattern having interplanar
spacing (d) values substantially at 6.41, 5.14, 4.79, 4.43, 4.27, 4.17, 4.06, and 3.69 ± 0.2
A. The crystalline form of vilazodone free base is further characterized by an XRPD
pattern having interplanar spacing (d) values substantially at 15.35, 12.05, 10.02, 8.07,
6.63, 6.41, 5.85, 5.55, 5.14, 4.79, 4.63, 4.43, 4.27, 4.17, 4.06, 3.85, 3.69, 3.54, 3.33, 3.20,
3.1 1, 3.03, 2.95, 2.89, 2.82, 2.70, 2.61, 2.52, and 2.32 ± 0.2 A.
XRPD of the samples were determined by using Panalytical X'Pert Pro X-Ray
Powder Diffractometer in the range 3-40 degree 2 theta and under tube voltage and current
of 45 Kv and 40 mA respectively. Copper radiation of wavelength 1.54 angstrom and
Xceletor detector were used.
In the following section, embodiments are described by way of examples to
illustrate the process of invention. Several variants of these examples would be evident to
persons ordinarily skilled in the art.
Example 1: Preparation of 5-|4-[4-r5-Cyano-lH-Indol-3-yf)ButyllPiperazin-l-yl}-l-
Benzofuran-2-Carboxamide
3-(4-Chlorobutyl)-lH-indole-5-carbonitrile (34.2 g) was added to acetonitrile (300
mL). Sodium iodide (33.1 g) was added to the reaction mixture. The reaction mixture
was heated to 80°C to 85°C and maintained for 60 minutes. The reaction mixture was
cooled to 60°C. 5-(Piperazin-l-yl)-l-benzofuran-2-carboxamide (30 g) and triethylamine
( 18.6 g) were added to the reaction mixture. The reaction mixture was heated to 80°C to
83°C for 18 hours. The reaction mixture was cooled to 20°C to 30°C. The reaction
mixture was added to water (300 mL), dichloromethane (300 mL), and sodium
thiosulphate (7.5 g). Concentrated hydrochloric acid (15 mL) was added to the reaction
mixture and stirred for 1.5 hours at 20°C to 30°C. The solid obtained was filtered and
washed with dichloromethane (80 mL) and deionized water (150 mL). The reaction
mixture was added to ethyl acetate (600 mL) and water (300 mL). Triethyl amine (20 g)
was added to the reaction mixture. The reaction mixture was heated to 70°C to 75°C. The
layers obtained were separated and the organic layer was washed with water (100 mL).
The organic layer was recovered under vacuum. 2-Propanol (60 mL) was added to the
reaction mixture and stirred at 20°C to 30°C for 1 hour. The reaction mixture was filtered,
washed with 2-propanol (30 mL) and dried under vacuum at 45°C to 50°C for 12 hours to
obtain the title compound having XRPD as depicted in Figure 1.
Yield: 44.0 g.
Example 2 : Preparation of 5-{4-r4-(5-Cvano-lH-Indol-3-yl)Butyl1Piperazin-l-yl}-l-
Benzofuran-2-Carboxamide
Potassium carbonate ( 11.3 g) was added to water (100 mL) and stirred for 10
minutes. 5-Piperazin-l-ylbenzofuran-2-carboxamide (20 g) and 3-(4-chlorobutyl)indole-
5-carbonitrile (20.9 g) were added to the reaction mixture. The reaction mixture was
heated to 98°C to 100°C and maintained for 5 hours. The reaction mixture was cooled to
50°C. Water (200 mL) was added to the reaction mixture. The solid obtained was filtered
and dried in an air oven at 50°C to 55°C for 10 hours to 12 hours to obtain the title
compound.
Yield: 18.0 g.
Example 3 : Preparation of 5-|4-[4-(5-Cyano-lH-Indol-3-yl)ButyllPiperazin-l-yl}-l-
Benzofuran-2-Carboxamide
Potassium carbonate (28.2 g) was added to water (250 mL) and stirred for 10
minutes. 5-Piperazin-l-ylbenzofuran-2-carboxamide (50 g), 3-(4-chlorobutyl)indole-5-
carbonitrile (52.3 g), and 2-propanol (250 mL) were added to the reaction mixture. The
reaction mixture was heated to 80°C to 85°C and maintained for 24 hours. The reaction
mixture was cooled to 30°C. Water (500 mL), dichloromethane (500 mL), and
hydrochloric acid (3N; 200 mL) were added to the reaction mixture and filtered. The solid
obtained was dissolved in ethyl acetate (1000 mL), triethylamine (50 mL), and water (100
mL) at 80°C to 83°C. The reaction mixture was filtered and the organic layer was
separated and recovered. The residue was treated with 2-propanol (150 mL) and filtered.
The solid obtained was dried under vacuum at 45°C to 50°C to obtain the title compound
having XRPD as depicted in Figure 2.
Yield: 57.5 g.
Example 4 : Preparation of 5-{4-r4-(5-Cvano-lH-Indol-3-yl)Butyl1Piperazin-l-yl}-l-
Benzofuran-2-Carboxamide
Potassium carbonate (28.2 g) was added to water (250 mL) and stirred for 10
minutes. 5-Piperazin-l-ylbenzofuran-2-carboxamide (50 g), 3-(4-chlorobutyl)indole-5-
carbonitrile (52.3 g), and 2-propanol (250 mL) were added to the reaction mixture. The
reaction mixture was heated to 80°C to 85°C and maintained for 24 hours. The reaction
mixture was cooled to 25°C to 30°C and filtered. The reaction mixture was added to
dichloromethane (350 mL), methanol (350 mL), and concentrated hydrochloric acid (25
mL) at 30°C to 35°C. Water (350 mL) was added to the reaction mixture and the mixture
was stirred and filtered. The solid obtained was dissolved in ethyl acetate (1000 mL),
methanol (250 mL), and triethylamine (50 mL) at 80°C to 83°C. The reaction mixture
was washed with water and the organic layer was recovered. The reaction mixture was
treated with methanol (150 mL) and filtered. The solid obtained was dried under vacuum
at 50°C to 55°C to obtain the title compound.
Yield: 64 g.
XRD provided
Example 5 : Preparation of 5-i4-r4-(5-Cvano-lH-Indol-3-yl)Butyl1Piperazin-l-yl}-l-
Benzofuran-2-Carboxamide
Potassium carbonate (5.64 g) was added to water (50 mL) and stirred for 10
minutes. 5-Piperazin-l-ylbenzofuran-2-carboxamide (10 g), 3-(4-chlorobutyl)indole-5-
carbonitrile (10.45 g), and 1-propanol (50 mL) were added to the reaction mixture. The
reaction mixture was refluxed at 85°C to 90°C and maintained for 11 hours. The reaction
mixture was cooled to 50°C. Water (100 mL) and hydrochloric acid (4N; 40 mL) were
added to the reaction mixture and filtered. Dichloromethane (150 mL), methanol (150
mL), and water (150 mL) were added to the reaction mixture. The reaction mixture was
treated with activated carbon ( 1 g), filtered through celite, and washed with
dichloromethane (50 mL) and water (50 mL). Triethylamine (10 mL) was added to the
reaction mixture, the layers obtained were separated and the organic layer was recovered
under vacuum. Methanol (20 mL) was added to the reaction mixture, stirred for 1.5 hours
and filtered. The solid obtained was dried at 45°C to 50°C to obtain the title compound.
Yield: 13 g.
Example 6 : Preparation of 5-{4-r4-(5-Cvano-lH-Indol-3-yl)Butyl1Piperazin-l-yl}-l-
Benzofuran-2-Carboxamide
5-Piperazin-l-ylbenzofuran-2-carboxamide (2.0 g) was added to 3-(4-
chlorobutyl)indole-5-carbonitrile (1.9 g) in dimethylformamide (20 mL). Potassium
carbonate (1.2 g) was added to the reaction mixture and heated to 80°C to 85°C and
maintained for 5 hours. The reaction mixture was cooled to 35°C and water (50 mL) was
added, stirred for 2 hours, and then filtered. The solid obtained was dried under vacuum at
45°C to 50°C to obtain the title compound.
Yield: 1.0 g.
Example 7 : Preparation of 5-{4-r4-(5-Cvano-lH-Indol-3-yl)Butyl1Piperazin-l-yl}-l-
Benzofuran-2-Carboxamide
Potassium carbonate (2.8 g) was added to water (25 mL) and stirred for 10
minutes. 5-Piperazin-l-ylbenzofuran-2-carboxamide (5.0 g), 3-(4-chlorobutyl)indole-5-
carbonitrile (5.7 g), and toluene (25 mL) were added to the reaction mixture and heated to
90°C to 95°C for 29 hours. The reaction mixture was cooled to 30°C, filtered and washed
with water (25 mL). The solid obtained was dried at 45°C to 50°C to obtain the title
compound.
Yield: 7.0 g.
Example 8: Preparation of 5-{4-r4-(5-Cvano-lH-Indol-3-yl)Butyl1Piperazin-l-yl}-l-
Benzofuran-2-Carboxamide Hydrochloride
5- {4-[4-(5-cyano- lH-indol-3-yl)butyl]piperazin- 1-yl} -1-benzofuran-2-
carboxamide (10.0 g) was added to 2-propanol (430 mL). The reaction mixture was
heated to 80°C to 83°C. The reaction mixture was filtered. The reaction mixture was
heated to 70°C to 80°C and a solution of 2-propnaolic hydrochloride (0.1N; 230 mL) was
added to the reaction mixture at 70°C to 80°C in 20 minutes. The reaction mixture was
cooled to 25°C to 30°C and stirred for 2.5 hours. The solid obtained was filtered, washed
with diethyl ether (30 mL) and dried under vacuum at 20°C to 30°C for 12 hours to obtain
the title compound.
Yield: 9.9 g.

We claim:
1. A process for the preparation of 5-{4-[4-(5-cyano-lH-indol-3-yl)butyl]piperazin-lyl}
-1-benzofuran-2-carboxamide of Formula I
FORMULA I
or its pharmaceutically acceptable salts which comprises:
a) reacting 3-(4-chlorobutyl)-lH-indole-5-carbonitrile of Formula II
FORMULA II
with 5-(piperazin-l-yl)-l-benzofuran-2-carboxamide of Formula III,
FORMULA III
in the presence of base and solvent;
isolating the compound of Formula I from the reaction mixture thereof; and
optionally converting the compound of Formula I to its pharmaceutically
acceptable salts.
2. The process according to claim 1, wherein the base is selected from a group
consisting of an organic base or an inorganic base.
3. The process according to claim 2, wherein the organic base is selected from
triethylamine, diisopropylamine, diisopropylethylamine, 4-dimethylaminopyridine,
pyrollidine or N-methyl morpholine.
4. The process according to claim 3, wherein the organic base is triethylamine.
5. The process according to claim 2, wherein the inorganic base includes hydroxides
or carbonates and bicarbonates of alkali or alkaline metal.
6. The process according to claim 5, wherein the carbonates and bicarbonates of
alkali or alkaline metal is sodium carbonate, potassium carbonate, magnesium carbonate,
sodium bicarbonate or potassium bicarbonate.
7. The process according to claim 2, wherein the inorganic base is potassium
carbonate.
8. The process according to claim 1, wherein the solvent is selected from a group
consisting of water, organic solvent, or a mixture thereof.
9. The process according to claim 8, wherein organic solvents are selected from a
group consisting of alcohol, ketone, nitrile, amide, aromatic or aliphatic hydrocarbon, or
dimethyl sulfoxide.
10. The process according to claim 9, wherein the alcoholic solvent is methanol, 2-
propanol, or 1-propanol.
11. The process according to claim 9, wherein the amide solvent is Nmethylpyrrolidone
or dimethyl formamide.
12. The process according to claim 9, wherein the ketonic solvent is acetone or methyl
isobutyl ketone.
13. The process according to claim 9, wherein the aromatic hydrocarbon solvent is
toluene.
14. The process according to claim 1, wherein the solvent is water alone or in
combination with 2-propanol, 1-propanol, dimethylformamide, or toluene.
15. The process according to claim 1, wherein the reaction of the compound of
Formula II and the compound of Formula III is carried out in the presence of only water
without using any other solvent.
16. The process according to claim 1, wherein the pharmaceutically acceptable salt
includes hydrochloride salt.
17. A crystalline form of vilazodone free base with substantially the same XRPD (XRay
Powder Diffraction Pattern) as depicted in Figure 1 or Figure 2.
18. A crystalline form of vilazodone free base characterized by an XRPD having
interplanar spacing (d) values substantially at 6.41, 5. 14, 4.79, 4.43, 4.27, 4. 17, 4.06, and
3.69 ± 0.2 A.
19. The crystalline form of vilazodone free base according to claim 18 which is further
characterized by an XRPD having interplanar spacing (d) values substantially at 15.35,
12.05, 10.02, 8.07, 6.63, 6.41, 5.85, 5.55, 5.14, 4.79, 4.63, 4.43, 4.27, 4.17, 4.06, 3.85,
3.69, 3.54, 3.33, 3.20, 3.1 1, 3.03, 2.95, 2.89, 2.82, 2.70, 2.61, 2.52, and 2.32 ± 0.2 A.