to a thioamide dianion and subsequent ethylation afforded a N-thioacyl hemithioaminal. NMR studies on the thioamide mono- and dianionsderivedfrom N-benzyl 2-methoxythiobenzamide showed a linear relationship between the chemical shifts of all carbon atoms of thioamide mono- and dianions. The results also suggested that the negative charge at the benzylic carbon atom of the dianion is not fully delocalized
Optically pure phosphoroselenoyl chloride was reacted with racemic amines to give phosphoroselenoic amides as two diastereomeric mixtures in high yields. The diastereomeric mixtures were separated by fractional recrystallization or by chromatography. Extrusion of the selenium atom from the separated amides led to diastereomerically pure phosphoramidites. The ability of the obtained amidites to act as optically active ligands was tested in the hydrogenation of an imine.