Preparation of diastereomerically pure 9-carboxybicyclo[6.1.0]nonane derivatives
摘要:
Reactions of cyclooctene (1) with dibromocyanoacetic esters and copper(I) bromide give (8-10) : 1 mixtures of isomers (2, 3), not stereochemically pure compounds as reported by others. The stereochemistry is elucidated by independent synthesis of one diastereomer (3a). Carbenoid addition of alkoxycarbonylmethylene to 1 and 1,5-cyclooctadiene leads also to exo/endo adduct mixtures. Methods are developed to generate diastereomerically pure compounds (exo-7a, exo-8, endo-9, exo-10, endo-10) from these. Endo esters of this series undergo very facile base catalyzed epimerization.
Reductive Carbonylation of<i>gem</i>-Dihalogenocyclopropanes by Pentacarbonyliron(0) in the Presence of Sodium Methoxide
作者:Françoise Reyne、Bernard Waegell、Pierre Brun
DOI:10.1246/bcsj.68.1162
日期:1995.4
The reaction of gem-dihalogenocyclopropanes derivatives with (tetracarbonyl)(methoxycarbonylato)ferrate(I−) has been investigated; gem-dibromocyclopropanes and gem-chlorobromocyclopropane derivatives are reduced and carbonylated. It could be shown that a bromo ester such as methyl 1-bromo-2-phenylcyclopropanecarboxylate is an intermediate in the transformation of 1,1-dibromo-2-phenylcyclopropane into methyl cis- and trans-2-phenylcyclopropanecarboxylates and dimethyl 2-phenyl-1,1-cyclopropanedicarboxylate.
Preparation of diastereomerically pure 9-carboxybicyclo[6.1.0]nonane derivatives
作者:Eckehard Volker Dehmlow、Olaf Pl�ckebaum
DOI:10.1002/prac.19963380161
日期:——
Reactions of cyclooctene (1) with dibromocyanoacetic esters and copper(I) bromide give (8-10) : 1 mixtures of isomers (2, 3), not stereochemically pure compounds as reported by others. The stereochemistry is elucidated by independent synthesis of one diastereomer (3a). Carbenoid addition of alkoxycarbonylmethylene to 1 and 1,5-cyclooctadiene leads also to exo/endo adduct mixtures. Methods are developed to generate diastereomerically pure compounds (exo-7a, exo-8, endo-9, exo-10, endo-10) from these. Endo esters of this series undergo very facile base catalyzed epimerization.