Synthesis

Enantioselective Syntheses of 2-Alkyl-, 2, 6-Dialkylpiperidines and Indolizidine Alkaloids Through Diastereoselective Mannich-Michael Reactions

M Weymann, W Pfrengle, D Schollmeyer, H Kunz

Index: Weymann, Markus; Pfrengle, Waldemar; Schollmeyer, Dieter; Kunz, Horst Synthesis, 1997 ,  # 10  p. 1151 - 1160

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Citation Number: 48

Abstract

Aldimines of 2, 3, 4, 6-tetra-O-pivaloyl-fi-D-galactosylamine react with 1-methoxy-3- trimethylsilyloxybuta-1, 3-diene in a Mannich—Michael condensation reaction sequence to give 2-substituted N-galactosyl-5, 6-dehydropiperidin-4-ones 3 with high diastereoselectivity. The X-ray analysis of the 2-propyl derivative 3a proved (R)- configuration of the major diastereomer and led to the correction of our earlier assignment ...