Metal Carbene-Directed Intramolecular Vinylogous Reactions\nof Vinyldiazoacetates

Intramolecular addition reactions\nof electrophilic metallovinylcarbenes\nwith nucleophiles that do not have access to the carbene center undergo\naddition to the vinylogous position, forming products that rely on\nsubsequent transformations of vinylmetal intermediates. Catalytic\naddition to a carbon-carbon double bond elicits the formation of an\nintermediate carbocation whose proton loss causes protodemetalation\nof the vinylmetal intermediate. Addition to the azido group results\nin the formation of aliphatic 1,2,3-triazines by [3 + 3]-cycloaddition.\nCatalytic intramolecular reactions with a carbamate nucleophile yield\na carbonyl ylide whose loss of isobutylene produces oximidovinyl-oxazolidinone\nesters with high enantioselectivity. Comparisons are made between\nrhodium, copper, gold, and silver catalysts