Preparation of enantiopure 1‐isopentyl‐3‐methyl‐3‐phospholene 1‐oxide via the formation of diastereomeric complexes

The resolution of 1-isopentyl-3-methyl-3-phospholene 1-oxide via the formation of diastereomeric complexes using TADDOL derivatives or the Ca2+-salts of tartaric acid derivatives was studied. Both enantiomers of the 1-isopentyl-3-phospholene oxide were prepared in an enantiopure form with (R,R)-spiro-TADDOL, or with the acidic Ca2+-salt of O,O′-dibenzoyl-(R,R)-tartaric acid. The absolute configuration of the 1-isopentyl-3-phospholene oxide enantiomer with negative optical rotation was also substantiated by a study involving CD spectroscopy and theoretical calculations.