Resolution of Enantiomers of Novel C2-Symmetric Aminobisphosphinic Acids via Diastereomeric Salt Formation With Quinine

C2-symmetric N,N-bis(phosphinomethyl)amines were prepared by the thermal reaction of aromatic aldehydes with ammonia and hypophosphorus acid as previously described. Both enantiomers of C2-symmetric N,N-bis(phosphinomethyl)amine were obtained in a high enantiomeric purity through the diastereomeric salt formation with (–)-quinine, and subsequent fractional crystallization. X-ray crystallographic analysis of one of the diastereomeric salts clearly revealed that (–)-quinine could be an efficient resolving agent for obtaining the single enantiomer (R,R)-N,N-bis(phosphinomethyl)amine.

C2-symmetric; α-aminophosphinic acids; thermal reaction