Studien zur Biidung von Cyclopropan- und Oxiran-Derivaten in der Dreikomponentenreaktion von Basen, α-Halogen-acrylsäure-derivaten und Carbonylverbindungen

Abstract

The competitive formation of oxiranes 1 and cyclopropanes 2 in the reaction of 2-halogeno-acrylic acid-derivatives, carbonyl-compounds and bases is discussed. The product ratio 1: 2 depends strongly upon the acidity of the carbonyl-compound as well as the structure of the acrylic acid-derivative. Cyclopropanes 2 are predominantly formed in the base-induced reaction of 2-halogeno-acrylic acid-derivates and CH-acids bearing two geminal acidic H. Oxiranes 1 on the other hand are produced in a three-component-condensation of 2-halogeno-acrylic acid-derivatives, carbonyl-compounds and carbanions of CH-acids of a pKa 8 to 15, bearing only one acidic H. The utility of glycidonitriles 1b as intermediates is demonstrated by the conversion of 1b into the γ-keto-δ-spirolactone 4.