Regioselective Rh2(OAc)4-promoted reactions of methyl diazoacetate with terminal triple bond enynes

Abstract

The selective Rh₂(OAc)₄-promoted methoxycarbonylmethylenation of a triple bond in enynes, with a terminal triple bond, by methyl diazoacetate is established, and the main factors, affecting the regioselectivity of the process, are elucidated. The easy in situ[2 + 2]-dimerization of methyl 1-alkenylcyclopropene-3-carboxylates in dimethyl trans-1,2-dialkenyltricyclo[3.1.0.0^2,4]hexane-3,6-dicarboxylates 2 is found, and their thermal rearrangement into dimethyl trans-1,2-dialkenylcyclohexa-1,4-diene-3,6-dicarboxylates 7 is also described.