Structure of the endo 1: 1 adduct by asymmetric cycloaddition reactions of optically active (R)-allene-1,3-dicarboxylate with furan: determination of its absolute configuration by X-ray analysis

Asymmetric Diels-Alder reactions of optically active (R)-allene-1,3-dicarboxylate with furan in the presence of Lewis acid proceeded to afford the endo-adduct selectively in moderate yield. The absolute configuration of the adduct was confirmed by X-ray analysis