Patent ID: 6723856
Filing Date: 2004-04-20
Classification: A23L,C07D

Abstract:
An improved process for the preparation of 2-acetyl-1-pyrroline, the said process comprising steps of:a) dissolving L-proline in dry alcohol, cooling to a temperature in the range of âˆ’5Â° C. to âˆ’15Â° C., b) adding thionylchloride to step (a) solution, maintaining the temperature of reactant mixture below 0Â° C., c) stirring the reactant mixture of step (b) at a temperature range of 20Â° to 30Â° C. for a time period of 1 h to 4 h, d) removing the solvent from reactant mixture of step (c) to obtain a residue, which is stored in ice-chest for a time period of 10 h to 16 h to obtain a solid mass, e) adding the solid mass of step (d) to 50% aqueous alkali carbonate solution, extracting with an organic solvent, separating the organic and aqueous layer, f) drying the organic layer of step (e) over anhydrous sodium sulphate, filtering, evaporating the solvent from filtrate to obtain a residue, g) distilling the residue of step (f) to obtain 2-carbomethoxy-1-pyrrolidine, h) dissolving 2-carbomethoxy-1-pyrrolidine of step (g) in ether, cooling to a temperature range of 0Â° to 5Â° C., adding drop wise t-butylhypochlorite over a period of 10 minutes to 30 minutes, stirring at a temperature range of 20Â° to 30Â° C. for a time period of 4 h to 6 h, i) filtering the solution of step (h), removing the solvent from the filtrate to obtain 2-carbomethoxy-1-pyrroline, j) preparing Grignard Reagent in dry ether by adding magnesium turning, iodine followed by dropwise methyl iodide and stirring at a temperature in the range of 25Â° C. to 35Â° C. for completion of reaction, cooling the mixture to 0Â° C., k) adding an ethereal solution of 2-carbomethyoxy-1-pyrroline to the cooled mixture of step (j), stirring at a room temperature till the reaction is complete, k) adding 5% aqueous hydrochloric acid to step (k) mixture, extracting with diethyl ether, separating the organic layer, drying the organic layer over anhydrous sodium sulphate, filtering to obtain a filtrate, and l) distilling the filtrate of step (i) to obtain pure 2-acetyl-1-pyrroline.