Enantioselective formal [2 + 2 + 2] cycloaddition of 1,3,5-triazinanes to construct tetrahydropyrimidin-4-one derivatives.

A chiral Lewis acid-catalyzed enantioselective formal [2 + 2 + 2] cycloaddition of 1,3,5-triazinanes with azlactones or β,γ-unsaturated pyrazole amides was developed to synthesize chiral tertiary/quaternary tetrahydropyrimidin-4-one derivatives with good yields and enantioselectivities. Two competitive reaction pathways were proposed based on experiments.