An “on-water” exploration of CuO nanoparticle catalysed synthesis of 2-aminobenzothiazoles
作者:Saroj Kumar Rout、Srimanta Guin、Jayashree Nath、Bhisma K. Patel
DOI:10.1039/c2gc35575b
日期:——
An âon-waterâ one-pot process has been engineered for the preparation of 2-aminobenzothiazole from ortho-halo (âF, âCl, âBr and âI) substituted unsymmetrical thioureas. For ortho âI and âBr substrates the reactions afford 2-aminobenzothiazoles under metal free condition promoted by base. However, the relatively inert ortho âCl and âF substrates undergo intramolecular arylthiolation only in the presence of CuO nanoparticles yielding 2-aminobenzothiazoles. This methodology provides easy access to aminobenzothiazoles utilising even the ortho âCl and âF substrates. The catalyst is recyclable several times without loss of substantial activity. Other remarkable features include the wide range of functional group tolerance, absence of chromatographic purification (for ortho âI and âBr substrates) and providing moderate to excellent yield of the products under mild conditions, thus rendering the methodology as a highly eco-friendly alternative to the existing methods.
A concise construction of 12H-benzo[4,5]thiazolo[2,3-b]quinazolin-12-ones via an unusual TBHP/Na<sub>2</sub>CO<sub>3</sub> promoted cascade oxidative cyclization and interrupted Dimroth rearrangement
An interrupted Dimroth rearrangement was merged into the oxidative cyclization between isatins and 2-haloaryl isothiocyanates, giving 12H-benzo[4,5]thiazolo[2,3-b]quinazolin-12-one derivatives.
A facile one-pot, metal-free method for the synthesis of 2-aminobenzothiazoles was developed, which includes an initial reaction of electron-deficient 2-haloanilines with aromatic isothiocyanates and the subsequent intramolecular cyclization of the resulting thioureas through the SNAr mechanism. This one-pot, atom-economical, robust, and scalable method avoids the use of reagents such as acid chlorides
开发了一种简便的一锅法、无金属合成 2-氨基苯并噻唑的方法,包括缺电子 2-卤代苯胺与芳香族异硫氰酸酯的初始反应,以及随后通过 S N Ar 机制使所得硫脲发生分子内环化. 这种单锅、原子经济、稳健且可扩展的方法避免了使用难以处理的试剂,例如酰氯和 Lawesson 试剂。