Structural Effects on the Rh^II‐Catalyzed Rearrangement of Cyclopropenes

Abstract

Abstract The thermocatalytic rearrangement of 2‐alkylcycloprop‐2‐ene‐1‐carboxylates ( 1 ) in the presence of Rh II perfluorobutyrate is regio‐ and stereospecific and leads to the substituted metallocarbenes 3 . The latter undergo intramolecular CH bond insertion to form cyclopentylidenes ( 4 ). In contrast, the metallocarbenes 19 , derived from 2,3‐dialkylcycloprop‐2‐ene‐1‐carboxylates 6c , d , react to dienes ( Z )‐ 20 , via 1,2‐H migration. The cyclopropenedicarboxylates 10 , in turn, rearrange exclusively to the more substituted metallocarbenes 26 , which cyclize to furans 28 , With 6e , and 12 , products derived from both modes of ring‐opening are observed.