CYCLOPROPANATION REACTIONS WITH α,β-EPOXY DIAZOMETHYL KETONES AND REARRANGEMENT OF α,β-EPOXY CYCLOPROPYL KETONES

Article abstract of DOI:10.1016/0040-4020(80)80175-X

The cyclopropanation reactions of α,β-epoxy diazomethyl ketones 1 with olefins using Pd(OAc)2 as catalyst is described.Differently substituted epoxy diazo ketones 1a-f give with cyclohexene exo-norcarane derivatives. 3,3-Diphenyloxiranyl-2-diazomethyl ketone 1a reacts with olefins like isobutene, E- and Z-butene-2 to give epoxy cyclopropenyl ketones. 3,3-Diphenyloxiranyl-2 cyclopropyl ketones 2a and 9 undergo two consecutive rearrangement reactions with BF3 as catalyst.In the first step an epoxide rearrangement of 9 takes place to give β-ketoaldehyde 10, which in a second step rearranges to enolester 12.The latter reaction is most likely restricted to β-ketoaldehydes which have a quaternary α-C atom.A rationale for this unusual reaction has been proposed.