Diversity-oriented synthesis of spiro-substituted 1,3-thiazine library via a one-pot, two-step, three-component reaction

A sequential one-pot, two-step, three-component reaction for efficient synthesis of spiro-substituted 1,3-thiazine library has been developed. The syntheses were achieved by reacting cyanoacetamide with isothiocyanate derivatives to give rise to 2-cyano-3-mercaptoacrylamides, which are trapped in situ by various cycloketones through cyclization, providing multifunctionalized spiro-substituted 1,3-thiazine analogues. This procedure features short reaction time, generally good to excellent yields, easily available starting materials, and operational simplicity. This chemistry provides an efficient and promising synthetic strategy to diversity-oriented construction of the 1,3-thiazine skeleton.