Divergent Synthesis of Benzo[4,5]imidazo[2,1-<i>b</i>][1,3]thiazines and α-Trifluoromethyl-β-arylthio Tertiary Alcohols from 2-Mercaptobenzimidazoles and α-CF<sub>3</sub> Alkenes
Bin Wang, Honghe Lin, Ziren Chen, Yonghong Zhang, Fei Xue, Yu Xia, Shaofeng Wu, Weiwei Jin, Chenjiang Liu
Abstract
An efficient and metal-free approach for the divergent synthesis of 2-fluoro-3-aryl-4 H -benzo[4,5]imidazo[2,1- b ][1,3]thiazines and α -trifluoromethyl- β -arylthio tertiary alcohols from 2-mercaptoimidazoles and α -CF 3 alkenes has been developed. The chemoselectivity was well controlled by base or light; a series of 2-fluoro-3-aryl-4 H -benzo[4,5]imidazo[2,1- b ][1,3]thiazines were afforded via base-mediated sequential S N 2′- and S N V-type reactions. Meanwhile, α -trifluoromethyl- β -arylthio tertiary alcohols could be selectively achieved through visible-light-driven and electron donor–acceptor (EDA) complex-initiated radical cascade thiolation/hydroxylation in the absence of base, transition metal, and external photocatalyst.