Reference

A process for the preparation of (17a)-17-hydroxy-23-methyl-19,21-dinorchola-5(10),9(11)-dien-20(22)- yn-3-one cyclic 1,2-ethanediyl acetal

A process for the preparation of (17a)-17-hydroxy-23-methyl-19,21-dinorchola-5(10),9(11)-dien-20(22)- yn-3-one cyclic 1,2-ethanediyl acetal. Hazra, Braja Gobal; Pore, Vandana Sudhir; Joshi, Padmakar Laxman; Basu, Sourav (Council Scientific Industrial Research, India). Indian IN 185199 A 2 Dec 2000, 10 pp. (English). (India). CODEN: INXXAP. CLASS: ICM: C07C043-30. APPLICATION: IN 1996-DE2965 27 Dec 1996. DOCUMENT TYPE: Patent CA Section: 32 (Steroids) A process was disclosed for the prepn. of the title acetal I and comprised generating 3-methyl-1-butynyl lithium by the addn. of Bu lithium to the soln. of 1,1-dibromo-3-methyl-1-butene in org. solvent at a temp. ranging from -50°C to -60°C, maintaining the reaction mixt.In this article, certain chemicals are used. Some of their cas registry numbers are 5571-36-8 and 84371-65-3 at a temp. of -60 to -40°C for a period in the range of 1 to 2 h, adding to this resultant mixt. a soln. of diketo monoacetal II at a temp. ranging between 40°C to 0°C, stirring the mixt. for a period ranging from 1 to 2 h at a temp. in the range -10°C to 0°C, quenching the reaction mixt. with a quenching agent such as NH4Cl, HCl extn. the product in org. solvent, sepg. the org. layer and removing the solvent by evapn. below room temp. under vacuum, further purifying the crude product obtained by column chromatog. silica gel column to obtain the desired acetal I. Acetal I is a useful intermediate for the synthesis of mifepristone. .