Catalyst-free reductive cyclization of bis(2-aminophenyl) disulfide with CO2 in the presence of BH3NH3 to synthesize 2-unsubstituted benzothiazole derivatives

Xiao Li; Zhenbao Liu; Hailong Hong; Limin Han; Ning Zhu

doi:10.1039/d2ra03134e

Catalyst-free reductive cyclization of bis(2-aminophenyl) disulfide with CO₂ in the presence of BH₃NH₃ to synthesize 2-unsubstituted benzothiazole derivatives

RSC Adv. 2022 Jun 20;12(28):18107-18114. doi: 10.1039/d2ra03134e. eCollection 2022 Jun 14.

Authors

Xiao Li^{1

2

3}, Zhenbao Liu^{1

2

3}, Hailong Hong^{1

2

3}, Limin Han^{1

2

3

4}, Ning Zhu^{1

2

3}

Affiliations

¹ College of Chemical Engineering, Inner Mongolia University of Technology Hohhot 010051 China hanlimin_442@hotmail.com zhuning@imut.edu.cn.
² Key Laboratory of CO2 Resource Utilization at Universities of Inner Mongolia Autonomous Region Hohhot 010051 China.
³ Inner Mongolia Engineering Research Center for CO2 Capture and Utilization Hohhot 010051 China.
⁴ Wu Hai Vocational &Technical College Wu Hai 010070 China.

Abstract

An efficient and catalyst-free methodology for the reductive cyclization of various disulfides using BH₃NH₃ as a reductant and CO₂ as a C1 resource was developed. The desired 2-unsubstituted benzothiazole derivatives were obtained in good to excellent yields. Moreover, mechanism investigation demonstrated that BH₃NH₃ played an important role in the formation of benzothiazole. As a reducing agent, BH₃NH₃ reduced CO₂ and cleaved the S-S bond of the disulfide efficiently. In addition, the N-H bond of the amino group was also activated by BH₃NH₃. To the best of our knowledge, this is an unprecedented catalyst-free protocol for the synthesis of 2-unsubstituted benzothiazole from bis(2-aminophenyl) disulfide and CO₂.