Synthesis of 1,2‐Azaphosphinane 2‐Oxides and 1,2‐Azaphosphinine 2‐Oxides: δ‐Phosphonolactams and δ‐Phosphinolactams
Jiaxi Xu
Abstract
Abstract 1,2‐Azaphosphinane and 1,2‐azaphosphinine 2‐oxides, δ‐phosphonolactams and δ‐phosphinolactams, are important six‐membered azaphosphaheterocycles and crucial scaffolds of some biological and organic material compounds. Dibenzo[ c , e ][1,2]azaphosphinine 2‐oxides are both chiral ligands and precursors of chiral atropisomeric P,N‐biaryl ligands. Various synthetic methods of these azaphosphaheterocycles have been developed till now. They can be classified as cyclization, including cyclization of haloalkylphosphonamidates and phosphinamides, condensation of aminoalkylphosphonic/phosphinic acids, ring closing metathesis of N ‐allylallylphosphinamides, the palladium‐catalyzed cyclizations of 2‐alk‐1‐ynylarylphosphonamidates and N ‐(2‐bromoaryl)diarylphosphinamides, oxidative cyclization of 2‐arylarylphosphinamides, annulation, and cycloaddition. In this Focus Review, we have described various strategies for the synthesis of 1,2‐azaphosphinane and 1,2‐azaphosphinine 2‐oxides.