Investigation of the reaction of (R)-(+)- and (S)-(−)-α-methylbenzylammonium hypophosphites with benzaldehyde

GRAPHICAL ABSTRACT

ABSTRACT

Model reaction of (R)- and (S)-α-methylbenzylammonium hypophosphites with benzaldehyde was discussed in detail. The appropriate (R,S)- or (S,R)- vs (R,R)- or (S,S)-aminophosphinic acid derivatives were formed with low diastereoselectivity (dr = 1.1:1–4.1:1). The impact of different reaction conditions on diastereoselectivity and the influence of solvent on crystallization of the major (S,R)- or (R,S)-aminophosphinic acids were evaluated. Plausible mechanism of the reaction was presented. Preferential formation of diastereomeric (S,R)- or (R,S)-aminophosphinic acids was explained on the basis of PM6 semi-empirical calculations.

KEYWORDS:

• α-Aminophosphinic acids
• diastereoselective addition
• semi-empirical calculations

Acknowledgment

We thank Professor Piotr Paneth from the Institute of Applied Radiation Chemistry, Lodz University of Technology, for PM6 calculations.

Funding

The authors gratefully acknowledge financial support from the Polish National Science Centre, Grant No DEC-2011/03/B/ST5/01058.