A stereochemical approach to the Kabachnik–Fields reaction mechanism

A comparison of the diastereomeric composition of Kabachnik–Fields reaction products with those of two reactions simulating its stereo-controlling steps showed that only the ‘imine’ mechanism works in the (MeO)₂P(O)H–PhCHO-[(S),(R,S)-H₂NCH(Ph)Me] system, like in the phosphite–imine system; in a similar system containing (R,S)-sec-butylamine, additional ‘nucleophilic amination’ of the initially formed α-hydroxybenzyl phosphonate occurs.