7-Dimethylvinylidene-1-methoxybicyclo[4.1.0]heptane and Ethyl 1-Ethoxy-2-methylcyclopropane-3-carboxylate

Abstract

As part of a study of the effect of neighboring functional groups on the β-oxycyclopropylcarbonium ion system² from the viewpoints of the ease of preparation of its precursor β-oxycyclopropylcarbonyl compounds and the facility of its generation of β,γ-unsaturated carbonyl and γ-dicarbonyl units³ a small investigation of the consequences of modification of the starting materials of the initial cyclopropanation step, i.e. usually enol ethers or esters and carbenoid generators such as diazomethyl keto compounds, was undertaken. The following discussion illustrates cyclopropanations, resulting from the involvement of an enol ether with an allenic carbene and of an inol ether with diazoacetic ester, as well as the subsequent unravelling of the oxygenated three-membered rings.