Reaction of diazoalkanes with unsaturated compounds. 9 Catalyzed cyclomethylenation of trimethylsilylacetylenes by diazomethane

Abstract

The catalyzed reaction of methyl-, propyl-, and cyclopropyltrimethylsilylacetylenes with diazomethane in the presence of CuCl leads to the corresponding cyclopropenes and bicyclobutanes with overall yields of up to 70%, and also to the products of incorporation of a methylene group into the C3-H bond of the cyclopropenes formed (2–9%). Partial catalyzed isomerization of the 1-trimethylsilyl-2-cyclopropylcyclopropene formed from trimethylsilylcyclopropylacetylene, into 1-trimethylsilyl-1-cyclopropylallene (yield ∼50%) was discovered to proceed under the reaction conditions.