Synthesis of novel enantiomerically pure C3-symmetric trialkanolamine ligand containing phosphoryl groups

Catalytic activity of ten metal salts in the reaction of benzhydrylamine and benzylamine with diethyl 2,3-epoxypropylpliosphonate (1) was studied. Only in the presence of copper(l) iodide pure diethyl 3-benzhydrylamino- and 3-benzylamino-2-hydroxypropylphosphonates were produced quantitatively. Although the reactions catalysed by calcium(H) triflate were the fastest, they led to the contamination of the major products with the respective bisphosphonates. Enantiomerically pure (S,S)-bis[2-(O,O-diethylphosphorylmethyl)ethanol] amine (10) was prepared in a Ca(OTf)(2)- catalysed reaction of (S)-1 (ee 94%) with 0.4 equivalent benzylamine followed by hydrogenolysis. The bisphosphonate (S S)-10 was transformed into enantiomerically pure (S,S,S)-tris[2-(O,O-diethyphosphorylmethyl)ethanol]amine (2), when reacted with (S)-1 (ee 94%) or into (R,S,S)-2, when (R)-1 (ee 94%) was used.