Stereoselective hydride reductions of cyclic N-diphenylphosphinyl imines. Highly diastereoselective syntheses of protected primary amines

Article abstract of DOI:10.1021/jo00128a009

Reduction of N-diphenylphosphinyl imines of variously substituted cyclohexanones, cyclopentanones, and bicyclic ketones with lithium tri-sec-butylborohydride provides highly diastereoselective procedures for the syntheses of N-diphenylphosphinyl amines which represent protected primary amines that can be unmasked by mild acidic cleavage. Attack of cyclohexyl derivatives occurs almost exclusively via equatorial approach to yield axial amine derivatives while cyclopentyl and bicyclic imines are attacked from the less sterically encumbered faces.