Formation of Acetylenic Acetals by Ring Opening of 1,1,2-Trihalocyclopropanes under Phase-Transfer Conditions.
作者:Leiv K. Sydnes、Einar Bakstad、Morten Heide、Georg W. Jensen、Inge L. Møller、Ruby I. Nielsen、Carl Erik Olsen、Connie N. Rosendahl、Monika Haugg、Nathalie Trabesinger-Rüf、Elmar G. Weinhold
DOI:10.3891/acta.chem.scand.50-0446
日期:——
A number of substituted 1,1-dibromo- and 1,1-dichlorocyclopropanes with an additional chlorine or bromine atom attached to C-2 were synthesized in reasonable to good yields by dihalocarbene addition to the corresponding alkenes under phase-transfer conditions. When the trihalides were treated with 50% aqueous sodium hydroxide in the presence of ethanol, triethylbenzylammonium chloride and dichloromethane, most of the compounds underwent ring opening and afforded mixtures of acetylenic acetals, usually in good yields. The reaction most likely involves cyclopropene intermediates, which in some cases also rearrange to a minor extent to the corresponding vinylcarbenes and afford alpha,beta-unsaturated aldehydes.