摘要:
Diphenylmethylenecyclobutane (5) in diethyl ether reacts smoothly at room temperature with lithium powder, whereby a cyclobutane segma-bond is reductively cleaved. The 1,4-dilithio compound 7 which is formed primarily, however, slowly undergoes rearrangement with 1,7-proton shift yielding another, presumably double-bridged 1,4-dilithio compound 8, which is rather stable in diethyl ether.