Enantioselective Synthesis of Highly Functionalized Phosphonate-Substituted Pyrans or Dihydropyrans Through Asymmetric [4+2] Cycloaddition of β,γ-Unsaturated α-Ketophosphonates with Allenic Esters

Tell me which you want: Catalytic asymmetric [4+2] cycloadditions of β,γ‐unsaturated α‐ketophosphonates with allenic esters catalyzed by organocatalysts derived from different cinchona alkaloids have been developed, affording phosphonate‐substituted functionalized pyran and dihydropyran derivatives in excellent yields with high enantioselectivities under mild conditions. The choice of product is controlled by the hydrogen bonding characteristics of the chosen catalyst.