Abstract The cyclizations of L-(+)-prolinol 5 with (thio) phosphoro (-no) dichloridates 6 give 1, 2, 3-azaphosphaoxabicyclo [3.3. 0] octanes 7 consisting of unequal amounts of diastereoisomers, eight pairs of which have been successfully resolved by silica gel column chromatography or recrystallization. The influences of reaction temperature, solvent and substrate concentration upon the asymmetric induction have also been investigated.
