摘要:
Transition-metal-substituted phosphorus ylides M(NtBu)2(CH=PPh3)Cl, with M=Mo, W, have been shown to be useful C-nucleophiles for the selective C-0 bond cleavage of benzocoumarin-type ''axially prostereogenic'' biaryl lactones. The reaction of the metallo-ylide with the lactone leads to an eight-membered metallacycle as established by spectroscopic data and confirmed by an X-ray diffraction study of one of the products.