Oakes-Yavari-Nair (OYN)-based Synthesis of Imidazo[۲,۱-b][۱,۳]thiazin-۷-imines and Imidazo[۲,۱-b][۱,۳]thiazin-۷-amines with Thiohydantoins, Isocyanides, Acetylenedicarboxylates

Hydantoin and thiohydantoin derivatives are important core moiety in the design and synthesis of heterocyclic compounds as well as medical products with good biological activity, these derivatives are very useful building blocks for the synthesis of various heterocycles with hypothermic activities, antibacterial, fungicidal activity and other pharmaceuticals properties. The three component reaction of stoichiometric amounts of acetylenedicarboxylates with alkyl isocyanides in the presence of ۲-thiophenytoins afforded imidazo[۲,۱-b][۱,۳]thiazines as a imine compounds and then these imines produce target amines in the present of catalyst in good overall yields. To choose the best catalyst among various common acidic catalys, PTSA has the best yield in the shortest reaction time. Finally the stereochemistry of the Imidazo[۲,۱-b][۱,۳]thiazin-۷-imines was studied by NOE spectra. We have developed a simple and useful method for the synthesis of functionalized imidazo[۲,۱-b][۱,۳]thiazines in two methods. The present method carries the advantage that not only is the reaction performed under mild conditions, but also the starting materials and reagents can be mixed without any activation or modification.