Applications of vinylogous mannich reactions. Concise enantiospecific total syntheses of (+)-croomine

SF Martin, KJ Barr, DW Smith…

Index: Martin, Stephen F.; Barr, Kenneth J.; Smith, Dudley W.; Bur, Scott K. Journal of the American Chemical Society, 1999 , vol. 121, # 30 p. 6990 - 6997

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Citation Number: 100

Abstract

Because the vinylogous Mannich reaction of substituted furans with iminium ions is a useful construction in alkaloid synthesis, it is important to know what effects substituents on the two reacting partners have upon the stereoselectivity of the reaction. Toward this end, the additions of the methylated furans 9a-h to the iminium ion generated in situ from the ethoxy carbamate 10 were examined. Generally, mixtures (3-24: 1) of the threo and erythro ...