Gold-catalyzed cyclization-cycloaddition cascade reactions of allenyl acetals with nitrones.

Gold and silver: when allenyl acetals and nitrones are treated with a catalytic amount of a gold complex and a silver salt they react through a cyclization-cycloaddition cascade reaction to give a mixture of diastereomeric tricyclic products. The mixture converges to a single product upon acid hydrolysis. The key intermediate is postulated to be a 1-methoxyfulvene species.