T3P-promoted synthesis of a series of novel 2-aryl-3-phenyl-2,3,5,6-tetrahydro-4H-1,3-thiazin-4-ones

A series of twelve novel 2-aryl-3-phenyl-2,3,5,6-tetrahydro-4H-1,3-thiazin-4-ones was prepared at room temperature by T3P-mediated cyclization of C-aryl-N-phenyl imines with 3-mercaptopropionic acid. The reaction can also be run as a 3-component reaction, forming the imine in situ. The reactions were operationally simple, rapid and gave yields as high as 75%. This provides ready access to C-aryl-N-phenyl compounds in this family, which have been generally difficult to prepare.