Structural Effects on the RhII-Catalyzed Rearrangement of Cyclopropenes

Article abstract of DOI:10.1002/hlca.19930760134

The termocatalytic rearrangement of 2-alkylcycloprop-2-ene-1-carboxylates (1) in the presence of Rh^II perfluorobutyrate is regio- and stereospecific and leads to the less 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 metallocarbene 26, which cyclize to furans 28.With 6e and 12, products derived from both modes of ring-opening are observed.