Asymmetric synthesis of 2-alkyl (aryl)-2, 3-dihydro-4-pyridones by addition of Grignard reagents to chiral 1-acyl-4-methoxypyridinium salts

…, SP Joseph, RR Goehring

Index: Comins, Daniel L.; Joseph, Sajan P.; Goehring, R. Richard Journal of the American Chemical Society, 1994 , vol. 116, # 11 p. 4719 - 4728

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Citation Number: 217

Abstract

Abstract: The asymmetric synthesis of 2-alkyl (aryl)-2, 3-dihydro-4-pyridones 3 by addition of various Grignard reagents to chiral 1-acyl-4-methoxypyridinium salts was studied in detail. Chiral pyridinium salts formed from 4-methoxy-3-(triisopropylsily1) pyridine (20, and (-)-8- arylmenthyl chloroformates, or (-)-trans-2-(a-cumyl) cyclohexyl chloroformate, gave the best results, with diastereomeric selectivities ranging from 60 to 94%. When 4-methoxy-3-( ...