o‐Hydroxyarylphosphanes: Strategies for Syntheses of Configurationally Stable, Electronically and Sterically Tunable Ambiphiles with Multiple Applications

Abstract

Abstracto‐Hydroxyarylphosphanes are fascinating compounds by their multiple‐reactivity features, attributed to the ambident hard and soft Lewis‐ and also Brønstedt acid‐base properties, wide tuning opportunities via backbone substituents with ±mesomeric and inductive, at P and in o‐position to P and O also steric effects, and in addition, the configurational stability at three‐valent phosphorus. Air sensitivity may be overcome by reversible protection with BH3, but the easy oxidation to P(V)‐compounds may also be used. Since the first reports on the title compounds ca. 50 years ago the multiple reactivity has led to versatile applications. This includes various P−E−O and P=C−O heterocycles, a multitude of O‐substituted derivatives including acyl derivatives for traceless Staudinger couplings of biomolecules with labels or functional substituents, phosphane‐phosphite ligands, which like the o‐phosphanylphenols itself form a range of transition metal complexes and catalysts. Also main group metal complexes and (bi)arylphosphonium‐organocatalysts are derived. Within this review the various strategies for the access of the starting materials are illuminated, including few hints to selected applications.