One-step synthesis of oxodimethylenemethane-transition metal complexes and palladium-catalyzed cycloaddition reaction

Some alkyl allyl carbonates and an allylammonium chloride bearing (1-(butyloxy)ethyl)oxy group at the 2-position of the allyl group were synthesized and successfully transformed to oxodimethylenemethane-palladium and -platinum complexes in one step by mixing with a transition metal-(0) and triphenylphosphine. On the basis of the confirmation of vinyl ether formation by H-1 NMR, the generation of oxodimethylenemethane complexes was rationalized to occur through abstraction of the beta-hydrogen on the acetal carbon by an alkoxide ion which was generated from the allyl carbonate upon oxidative addition of the transition metal. The palladium-catalyzed cycloaddition of the acetonylidene group to strained olefins also proceeded successfully by using these alkyl allyl carbonates.