³¹P NMR DETERMINATION OF THE ENANTIOMERIC COMPOSITION OF N-PROTECTED 1-AMINOALKYLPHOSPHONATES USING 1-(1-NAPHTHYL)ETHYLAMINE AND EPHEDRINE AS THE CHIRAL AGENTS

Abstract

Optically active 1-(1-naphthyl)ethylamine as well as ephedrine with N-protected 1-aminoalkylphos-phones form in equimolar ratio in CDCl₃ diastereoisomeric salts distinguished in ³¹P NMR spectroscopy. The magnetic nonequivalence of phosphonate groups are in almost all cases large enough (Δδ ³¹P is up to 0.8 ppm) to determine enantiomeric excess values. Amide cis-trans isomerism were observed in the case of aminophosphonates with urethane type of N-protected group. Two in ³¹P NMR distinguishable forms of diastereoisomeric systems of N-phthaloyl protected acid with ephedrine exist in CDCl, solution. The forms exhibit the reversal in the sense of the magnetic nonequivalence.

Key Words:

• Enantiomeric excess (ee)
• 1-aminoalkylphosphonates
• ³¹P NMR magnetic nonequivalence
• 1-(1-naphthyl)ethylamine
• ephedrine
• diastereoisomeric salts.