[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.

Hydrophosphination of propargylic alcohols and amines with phosphine boranes.

The first uncatalyzed hydrophosphinations of propargylic amines and alcohols with phosphine- borane complexes are described. The reactions proceed at ambient temperature or below without the use of protecting groups or the need to handle pyrophoric secondary phosphines, furnishing air-stable phosphineborane-amines and alcohols in good yields. Utilization of chiral propargylic substrates and unsymmetrical secondary phosphineboranes leads to diastereomeric P-chiral products that can be separated by fractional crystallization or chromatography. Initial applications of these new P-X species to asymmetric catalysis are detailed.