Metal Carbene-Directed Intramolecular Vinylogous Reactions of Vinyldiazoacetates

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