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.