A number of 1- and 1,2-disubstituted cyclopropenes undergo [4+2]-cycloaddit
ion to methyl vinyl ketone or acrolein at ambient temperature to produce 2-
oxabicyclo[4.1.0]hept-3-enes. When 1-phenyl-2-trimethylsilyl cyclopropene i
s treated with 0.4 mel. equiv. of m-chloroperbenzoic acid, the derived ring
-opened enone undergoes [4+2]-cycloaddition to the remaining starting mater
ial at ambient temperature. (C) 2000 Elsevier Science Ltd. All rights reser
ved.