Carbene‐Catalyzed and Pnictogen Bond‐Assisted Access to PIII‐Stereogenic Compounds

Abstract

AbstractIntermolecular pnictogen bonding (PnB) catalysis has received increased interest in non‐covalent organocatalysis. It has been demonstrated that organic electron‐deficient pnictogen atoms can act as prospective Lewis acids. Here, we present a catalytic approach for the asymmetric synthesis of chiral PIII compounds by combining intramolecular PnB interactions and carbene catalysis. Our design features a pre‐chiral phosphorus molecule bearing two electron‐withdrawing benzoyl groups, resulting in the formation of a σ‐hole at the P atom. X‐ray and non‐covalent interaction (NCI) analysis indicate that the model substrates exhibit intrinsic PnB interaction between the oxygen atom of the formyl group and the phosphorus atom. This induces a conformational locking effect, leading to the crystallization of the phosphorus substrate in a preferred conformation (P212121 chiral group). Under the catalysis of N–heterocyclic carbene, the aldehyde moiety activated by the pnictogen bond selectively reacts with an alcohol to yield the corresponding chiral monoester/phosphorus product with excellent enantioselectivity. This Lewis acidic phosphorus center, aroused by the non‐polarized intramolecular pnictogen bond interaction, assists in conformational and selective regulations, providing unique opportunities for catalysis and beyond.