Vinylogous Wolff rearrangement of cyclic β,γ-unsaturated diazomethyl ketones: a new synthetic method for angularly functionalised polycyclic systems

Decomposition of the rigid polycyclic β,γ-unsaturated diazomethyl ketones (1a) and (1b) and (2a) and (2b) promoted by 'activated CuO', Cu(acac)2, Cu(OTf)2, or Ni(acac)2 in the presence of methanol are shown to give mainly the corresponding rearranged γ,δ -unsaturated angularly substituted esters (3a) and (3b) and (8a) and (8b) together with the α-methoxy ketones (4a) and (4b) and (9a) and (9b). While photo-Wolff rearrangement of the diazo ketones leads to the corresponding homologous esters (5a) and (5b) and (10a) and (10b) the silver benzoate-triethylamine induced reaction gives the rearranged esters in addition to the homologous esters