A novel reductive aminocyclization for the syntheses of chiral pyrrolidines: stereoselective syntheses of (S)-nornicotine and 2-(2′-pyrrolidyl)-pyridines

TP Loh, JR Zhou, XR Li, KY Sim

Index: Loh, Teck-Peng; Zhou, Jian-Rong; Li, Xu-Ran; Sim, Keng-Yeow Tetrahedron Letters, 1999 , vol. 40, # 44 p. 7847 - 7850

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Citation Number: 20

Abstract

(S)-Nornicotine 2 was synthesized in four steps. A key step in the synthesis involved reductive aminocyclization of a 1, 4-ketoaldehyde with 2, 3, 4, 6-tetra-O-pivaloyl-β-d- galactosylamine 1 in the presence of sodium cyanoborohydride, diastereoselectively affording the corresponding stereoisomer 6 in 45% yield. The aminosugar moiety could be easily removed by acidic hydrolysis to furnish 2. The aminocyclization was further ...