The reductive decyclizations of semibullvalene
Abstract
Reduction of semibullvalene (5) with potassium more closely resembles deprotonation of tetrahydropentalenes by n-butyl-lithium-potassium t-pentoxide than it does the reduction of (5) with lithium; the former prccesses both provide the cyelo-octatetraenyl dianion (4), plausibly via the intermediate bicyclo[3.3.0]octadienediyl dianion (3).