2,3]-Sigmatropic rearrangements of 2-phosphineborane 2-propen-1-ols: rapid access to enantioenriched diphosphine monoxide derivatives

Hydrophosphination of secondary propargylic alcohols generates phosphine-containing allylic alcohols that undergo facile [2,3]-sigmatropic rearrangements with chlorophosphines, furnishing highly enantioenriched, crystalline diphosphine monoxides. The configuration at the newly formed stereocenter is opposite to that expected based on prior studies, and an ab initio computational evaluation of the possible transition states was performed to help explain the stereochemical course of the reaction.