Racemic resolution of N-protected alanine by strychnine and brucine versus donor/acceptor capability

The crystal structures of strychninium N-phthaloyl-D-alpha-alaninate 2 hydrate (1) and brucinium N-phthaloyl-L-alpha-alaninate 0.5 hydrate ( 2) were obtained as a result of racemic resolution by stereochemically related strychnine and brucine, respectively. Comparison of crystal structures of 1 and 2 with previously presented crystal structures of strychnine with N-benzoyl-L- and brucine with N-benzoyl-D-alanine points at the importance of alkaloid self-assemblies in molecular recognition. Simultaneously, various donor/acceptor capabilities of both alanine derivatives control acceptors' access of resolving agent self-assemblies and therefore racemic resolution.