Intramolecular heteroconjugate addition of heterocumulenes to α,β-unsaturated carbonyl compounds promoted by the CS2/TBAF system

We describe a new method for the preparation of dihydroquinazoline-2-thione and 4H-3,1-benzothiazine-2-thione derivatives by intramolecular heteroconjugate addition of carbodiimides or isothiocyanates bearing one o-substituted α,β-unsaturated carbonyl fragment promoted by the CS2/TBAF system.