A practical and efficient method for the resolution of 3-phospholene 1-oxides via coordination complex formation.

A simple, efficient, and economical method based on the combination of the exceptional behavior of o,o'-dibenzoyl- or o,o'-di-p-toluyl-(2R,3R)-tartaric acid in chiral recognition processes, and the coordination ability of calcium or magnesium ion was developed for the resolution of phospholene oxides 1. The calcium or magnesium salt of (-)-o,o'-dibenzoyl-(2R,3R)-tartaric acid 2,4-6 or calcium hydrogen (-)-o,o'-di-p-toluyl-(2R,3R)-tartrate 3 may form crystalline diastereomeric coordination complexes with the appropriate antipode of substituted 3-phospholene oxides 1 that makes possible efficient resolutions. Optically active phospholene oxides 1 were prepared directly by simply crystallization and digestion of the corresponding diastereomeric complexes so formed. Thermal behavior of the crystalline diastereomeric complexes was studied by simultaneous TG/DTA. The novel method may be of more general value in respect of the resolution of tertiary phosphine oxides.