Stereoselectrive Syntheses of Ephedrine and Related 2-Aminoalcohols of High Optical Purity from Protected CyanohydrinsJackson et al Tetrahedron Letters, 31, 10, 1447-1450 (1990) (https://www.thevespiary.org/rhodium/Rhodium/pdf/ephedrine.grignard.pdf)
(https://www.thevespiary.org/rhodium/Rhodium/pdf/ephedrine.grignard.pdf)
Abstract: Ephedrine and related optically active b-aminoalcohols can be prepared by zinc borohydride reduction of aryl O-protected magnesium imines and aryl a-hydroxyimimes which in turn are readily available from optically active cyanohydrins.