Chiral Phosphoric Acid‐Catalyzed Enantioselective Formal [4+2] Cycloaddition Between Dienecarbamates and 2‐Benzothioazolimines

An enantioselective chiral phosphoric acid catalyzed formal [4+2] cycloaddition between 2-benzothiazolimines and N-H-1,3-dienecarbamates is described. A divergence in reaction pathways was observed depending on the dienes employed. The performed with 4-substituted produced benzothiazolopyrimidines as major product yields ranging from 42 to 67%, single diastereoisomer enantioselectivity 93 99%. same 3-substituted dienes, however, gave highly enantioenriched 1,2,3,4-tetrahydroquinolines products albeit moderate diastereoselectivity.