X‐RAY ANALYSIS OF PYRROLIZIDINES SYNTHESIZED BY DIASTEREOSELECTIVE α‐CYCLISATION OF CAPTODATIVE OR PUSH‐PULL ENAMINES WITH DIMETHYL ACETYLENEDICARBOXYLATE

作者：B. Tinant, J. FENEAU‐DUPONT, J. P. Declercq, Benoît De Boeck, S. JIANG, Zdeněk Janoušek, H. G. VIEHE · 发表于：Bulletin des Sociétés Chimiques Belges · 年份：1995 · DOI：10.1002/bscb.19951040607 · 被引用次数：2 · 研究领域：Synthesis and Reactions of Organic Compounds、Chemical Reaction Mechanisms、Asymmetric Synthesis and Catalysis

Abstract The title reactions lead to unique diastereoisomers of pyrrolizidines 1a [dimethyl 2,3‐dehydro‐1‐methyl‐3‐cyanopyrrolizidine‐1,2‐dicarboxylate] or 1b [dimethyl 2,3‐dehydro‐1‐(ethoxycarbonylmethyl)l‐3–phenyl‐pyrrolizidine‐1,2‐dicarboxylate] with relative stereochemistry ( 1a : trans; 1b : cis ) established by X‐ray diffraction analysis. The heterocycle adopts a different conformation in 1a and 1b .