Transition metal catalyzed reactions of diazoesters. Cyclopropanation of dienes and trienes

The regioselectivity of the cyclopropanation of polyenes by cycloaddition of carbenes generated by catalyzed decomposition of diazoesters in the presence of Rh, Pd and Cu catalysts can be controlled to some extent by selecting proper reaction parameters. For a particular diene, the regioselectivity depends both on the catalyst and on the nature of the double-bond (conjugation, substitution). The cyclopropanation of trienes containing both a conjugated diene system and an isolated double bond is reported as an application of these reactions. The practical interest of the present study is further demonstrated by the synthesis of a pyrethroid precursor by the rhodium(II) carboxylates catalyzed-cyclopropanations of 1.1-dichloro-4-methyl-1, 3-pentadiene. © 1983.