A CARBENOID ROUTE TO C(1)-C(11)BRIDGED STEROIDS

Article abstract of DOI:10.1016/S0040-4039(00)97016-3

The exocyclic olefin 3 enters into stereoselective cyclopropanations with dihalocarbenes on the steroid β-face to afford the protected spiro<2.5>octane analogues 4 and 5.These intermediates are transformed into novel, highly strained steroid derivatives, like 9, by utilizing an intramolecular cyclopropylidene insertion reaction en route to pentacyclic, C(1)-C(11)ethano-bridged steroids 13-20.