jo2017444_si_001.pdf (1.32 MB)
Copper-Mediated C–H Activation/C–S Cross-Coupling of Heterocycles with Thiols
journal contribution
posted on 2016-02-22, 17:10 authored by Sadananda Ranjit, Richmond Lee, Dodi Heryadi, Chao Shen, Ji’En Wu, Pengfei Zhang, Kuo-Wei Huang, Xiaogang LiuWe report the synthesis of a series of aryl- or alkyl-substituted
2-mercaptobenzothiazoles by direct thiolation of benzothiazoles with
aryl or alkyl thiols via copper-mediated aerobic C–H bond activation
in the presence of stoichiometric CuI, 2,2′-bipyridine and
Na2CO3. We also show that the approach can be
extended to thiazole, benzimidazole, and indole substrates. In addition,
we present detailed mechanistic investigations on the Cu(I)-mediated
direct thiolation reactions. Both computational studies and experimental
results reveal that the copper–thiolate complex [(L)Cu(SR)]
(L: nitrogen-based bidentate ligand such as 2,2′-bipyridine;
R: aryl or alkyl group) is the first reactive intermediate responsible
for the observed organic transformation. Furthermore, our computational
studies suggest a stepwise reaction mechanism based on a hydrogen
atom abstraction pathway, which is more energetically feasible than
many other possible pathways including β-hydride elimination,
single electron transfer, hydrogen atom transfer, oxidative addition/reductive
elimination, and σ-bond metathesis.