Double C-S bond formation via multiple Csp3-H bond cleavage: synthesis of 4-hydroxythiazoles from amides and elemental sulfur under metal-free conditions.

A novel and efficient approach for the synthesis of 4-hydroxythiazoles from amides and elemental sulfur has been developed. In the presence of P2O5, DMSO and HMPA, this metal-free protocol proceeds smoothly and tolerates a spectrum of functional groups. Furthermore, this strategy involves the process of double Csp3–S bond formation through the cleavage of multiple Csp3–H bonds for the first time.