I2-Induced Umpolung: Synthesis of a 1,6-Dihydrofuro[3,2-b]pyrazolo[3,4-e][1,4]thiazine Skeleton via an Unconventional 1,4-Dithiane-2,5-diol Reaction Mode

In this paper, novel sulfur-containing 1,6-dihydrofuro[3,2-b]pyrazolo[3,4-e][1,4]thiazine skeletons were constructed from the simple and readily available materials enaminone, 5-aminopyrazole, and 1,4-dithiane-2,5-diol. Furthermore, a novel 1,4-dithiane-2,5-diol reaction mode has been developed through a double-dipole-reversal process induced by iodine that results in the formation of six new bonds and two new rings in a one-pot reaction. This method shows good substrate compatibility, and the products can be further modified with a variety of pharmaceuticals. Additionally, this novel skeleton exhibits good fluorescence properties in solution, enabling bright and stable green fluorescence imaging in HeLa cells.