Divergent Synthesis\nof Benzo[4,5]imidazo[2,1‑<i>b</i>][1,3]thiazines\nand α‑Trifluoromethyl-β-arylthio\nTertiary Alcohols from 2‑Mercaptobenzimidazoles and α‑CF<sub>3</sub> Alkenes

An efficient and metal-free approach\nfor the divergent\nsynthesis\nof 2-fluoro-3-aryl-4<i>H</i>-benzo[4,5]imidazo[2,1-<i>b</i>][1,3]thiazines and <i>α</i>-trifluoromethyl-<i>β</i>-arylthio tertiary alcohols from 2-mercaptoimidazoles\nand <i>α</i>-CF<sub>3</sub> alkenes has been developed.\nThe chemoselectivity was well controlled by base or light; a series\nof 2-fluoro-3-aryl-4<i>H</i>-benzo[4,5]imidazo[2,1-<i>b</i>][1,3]thiazines were afforded <i>via</i> base-mediated\nsequential S<sub>N</sub>2′- and S<sub>N</sub>V-type reactions.\nMeanwhile, <i>α</i>-trifluoromethyl-<i>β</i>-arylthio tertiary alcohols could be selectively achieved through\nvisible-light-driven and electron donor–acceptor (EDA) complex-initiated\nradical cascade thiolation/hydroxylation in the absence of base, transition\nmetal, and external photocatalyst.