The conversion of ether bonds to hydroxyl via a base-promoted rearrangement of cyclic phosphine oxides

Abstract

Biphenyl derived secondary phosphine oxides having 2′-hydroxyl were prepared. The compounds were converted to hydroxymethyl phosphine oxides when reacted with formaldehyde. After chlorination and cyclization, a series of P,O-heterocycles were obtained. When treated with LDA, a rearrangement occurred to stereoselectively afford hydroxyl substituted cyclic phosphines. The rearrangement was proposed to occur via intra-molecular aromatic substitution (S_NAr) reactions, with an attack of a carbon anion on alkoxyl on an adjacent benzene cycle. P-Stereogenic secondary phosphine oxide was stereospecifically converted to a P,C,axial-stereogenic P-cycle.