Thionation of Optically Pure N-C Axially Chiral Quinazolin-4-one Derivatives with Lawesson's Reagent.

The reaction of various optically pure N-C axially chiral quinazolin-4-one derivatives with Lawesson's reagent proceeded without a marked decrease in optical purity to give optically active quinazoline-4-thione derivatives (93-99% ee) possessing a high rotational barrier in good yields.