Solid-Phase Synthesis of 1,3,5,6-Tetra-Substituted 3,5-Dihydroimidazo[4,5-c][1,2]Thiazin-4(1 H)-One 2,2-Dioxide Derivatives

The synthesis of 1,3,5,6-tetra-substituted 3,5-dihydroimidazo[4,5-c][1,2]thiazin-4(1H)-one 2,2-dioxide derivatives was optimized through solid-phase synthesis. Synthetic strategies such as Merrifield resin, Thorpe-Ziegler reaction, Mitsunobu reaction, intramolecular cyclization, and desulfonative nucleophilic substitution were employed to synthesize a total of 31 derivatives. The synthesis showed high yields of 72%–87% per step over 8 steps, resulting in an overall yield of 7%–33%, thereby developing an efficient synthetic route for the derivatives.