A process for the preparation of compound of general formula I wherein R 1, R 2 and R 3 are independently selected from the group consisting of hydrogen; -C 1 - C 15 alkyl; C 1 - C 15 alkenyl; -C 1 - C 15 alkynyl; phenyl; aralkyl; conjugated aromatic group; which may optionally be substituted with halo; nitro; alkoxy; cyano; hydroxy; amido or amino groups; or R 1 and R 2 may be taken together to form a cyclic compound which may optionally contain 1 to 4 heteroatoms, optionally the cyclic compound may contain a carbonyl compound; or R 1 and R 2 are independently selected from halo; nitro; alkoxy; cyano; hydroxyl; amido or amino groups; R 4 and R 5 are independently selected from hydrogen; -C 1 - C 15 alkyl; -C 1 - C 15 alkenyl; -C 1 -C 15 alkynyl; phenyl; aralkyl; conjugated aromatic group; which may optionally be substituted with halo; nitro; alkoxy; cyano; hydroxy; amido or amino groups; or COOR; or may be taken together to form a cyclic compound which may optionally contain 1 to 4 heteroatoms; optionally the cyclic compound may contain a carbonyl compound; and R is independently selected from hydrogen, -C 1 - C 15 alkyl, -C 1 - C 15 alkenyl; -C 1 -C 15 alkynyl; phenyl; aralkyl; which may optionally be substituted with the substituents selected from halo; nitro; alkoxy; cyano; hydroxy; amido or amino groups; and said process comprising the steps of: i. heating a mixture of amine and D-(-)-pantolactone in the ratio ranging between 1:1.5 to 1:2 in a solvent at a temperature in the range of 110 to 150°C for period in the range of 16 to 24 hrs followed by raising the temperature of the mixture to a temperature in the range of 200-230°C for period in the range of 15 to 25min to obtain crude reaction mixture; wherein X is independently selected from the group consisting of CH 2, O, NR', alkylidine or cyclopropyl; ii. cooling the crude reaction mixture as obtained in step (i) at temperature in the range of 25 to 30°C followed by purifying by silica gel column chromatography to obtain a compound of general formula I. R 1, R 2 and R 3 are independently selected from the group consisting of hydrogen; -C 1 - C 15 alkyl; C 1 - C 15 alkenyl; -C 1 - C 15 alkynyl; phenyl; aralkyl; conjugated aromatic group; which may optionally be substituted with halo; nitro; alkoxy; cyano; hydroxy; amido or amino groups; or R 1 and R 2 may be taken together to form a cyclic compound which may optionally contain 1 to 4 heteroatoms, optionally the cyclic compound may contain a carbonyl compound; or R 1 and R 2 are independently selected from halo; nitro; alkoxy; cyano; hydroxyl; amido or amino groups; R 4 and R 5 are independently selected from hydrogen; -C 1 - C 15 alkyl; -C 1 - C 15 alkenyl; -C 1 -C 15 alkynyl; phenyl; aralkyl; conjugated aromatic group; which may optionally be substituted with halo; nitro; alkoxy; cyano; hydroxy; amido or amino groups; or COOR; or may be taken together to form a cyclic compound which may optionally contain 1 to 4 heteroatoms; optionally the cyclic compound may contain a carbonyl compound; and R is independently selected from hydrogen, -C 1 - C 15 alkyl, -C 1 - C 15 alkenyl; -C 1 -C 15 alkynyl; phenyl; aralkyl; which may optionally be substituted with the substituents selected from halo; nitro; alkoxy; cyano; hydroxy; amido or amino groups; and i. heating a mixture of amine and D-(-)-pantolactone in the ratio ranging between 1:1.5 to 1:2 in a solvent at a temperature in the range of 110 to 150°C for period in the range of 16 to 24 hrs followed by raising the temperature of the mixture to a temperature in the range of 200-230°C for period in the range of 15 to 25min to obtain crude reaction mixture; wherein X is independently selected from the group consisting of CH 2, O, NR', alkylidine or cyclopropyl; ii. cooling the crude reaction mixture as obtained in step (i) at temperature in the range of 25 to 30°C followed by purifying by silica gel column chromatography to obtain a compound of general formula I.