Synthesis of 3,4-Dihydro-2H-1,3-thiazines from α-Enolic Dithioesters and 1,3,5-Triazinanes via a Formal (3 + 3) Annulation Reaction.

The synthesis of 3,4-dihydro-2H-1,3-thiazines from α-enolic dithioesters and 1,3,5-triazinanes has been achieved via a formal (3 + 3) annulation reaction under thermal conditions, where 1,3,5-triazinanes were utilized as three-atom synthons. This transformation is catalyst-free and additive-free.