Self‐Neutralizing Carbonic Acidic Catalyzed Synthesis of Benzothiazole Derivatives from Disulfides and Aldehydes in Water

• Published in: ChemistrySelect
• Main Authors: Liu, Bo, Zhu, Ning, Cui, ZhengQing, Liu, Lei, Hong, Hailong, Han, Limin
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2017
• Subjects: Carbonic acid
• Online Access: http://dx.doi.org/10.1002/slct.201601626; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fslct.201601626; https://onlinelibrary.wiley.com/doi/full/10.1002/slct.201601626

Abstract An environmental friendly method was developed for preparing benzothiazole derivatives via the reaction of ortho‐anilino disulfides with aldehydes promoted by Na 2 S⋅9H 2 O in a reversible CO 2 ‐H 2 O system without any other acid additive or organic solvent. Thus, this reaction system greatly simplifies post‐processing and allows for disposal without waste. The highly selective protocol affords the corresponding benzothiazoles from the reaction of disulfides and aldehydes with electron‐donating or withdrawing groups in good yields. Moreover, the dynamic equilibrium relationship between Na 2 S and the CO 2 pressure had been explored by 13 CNMR in high‐pressure NMR tube, which firstly demonstrated the carbonic acid was converted into CO 3 2− or HCO 3 − promoted by Na 2 S in low or high CO 2 pressure. Furthermore, the mechanism of Schiff base formation catalyzed by acid was confirmed by 1 HNMR, and the process of benzothiazole formation from disulfide mediated by Na 2 S in CO 2 ‐H 2 O system was also proposed.