Conversion of N-acyl-2, 3-dihydro-4-pyridones to 4-chloro-1, 2-dihydropyridines using the Vilsmeier Reagent. Synthesis of (-)-coniine and (±)-lupinine

RS Al-awar, SP Joseph, DL Comins

Index: Al-awar, Rima S.; Joseph, Sajan P.; Comins, Daniel L. Journal of Organic Chemistry, 1993 , vol. 58, # 27 p. 7732 - 7739

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Citation Number: 64

Abstract

The full details are given of a study on the conversion of dihydropyridones of the type 3 to 4- chloro-1, 2-dihydropyridines 4 using a Vilsmeier reagent. The use of 1 equiv of Vilsmeier reagent under mild conditions (ClCHCClZ, rt) transformed several racemic N-acyl-2, 3- dihydro-4-pyridones 3 to dihydropyridines 4 in very good to excellent yields (83-96%). A C-3 methyl group can be tolerated as was demonstrated in the preparation of 4-chloro-3- ...