The base-catalysed Tamura cycloaddition reaction: calculation, mechanism, isolation of intermediates and asymmetric catalysis

A combined experimental and computational investigation has revealed that the base-catalysed Tamura cycloaddition between homophthalic anhydride and activated alkenes/alkynes - a reaction previously thought of as a Diels-Alder type process - proceeds via a stepwise mechanism involving conjugate addition and ring closure; which allowed the first catalytic asymmetric alpha-substitution reactions to be demonstrated with up to >99% ee.