Practical and Scalable Entry to Halogenated 1,4-Thiazines Through a Domino Morin-Rearrangement/Halogenation of N,S-Acetals and their Arylation Based on Suzuki-Miyaura Coupling

Abstract

Thiazines frameworks bearing a halide X (X = I, Br or Cl) at α-position of their sulfur atom were prepared in one or twosteps. The approach consists on Morin-rearrangement of N,S-acetal using the user-friendly N-halogenating reagents (NIS, NBS, NCS, DBH, DIH) or ICl to provide 1,4-thiazines. The latter, provided successfully corresponding halogenated derivatives through interesting domino Morin-rearrangement/halogenation when an excess of halogenating agents, which act as catalyst and halogenating reagent in the same operation, was used. The brominated 1,4-thiazines, obtained in good to excellent yields, were then arylated through Pd(0)-catalyzed Suzuki-Miyaura coupling with organoboronic acids or esters.Ultimately, these conditions were applied to one example of amidation reaction.