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Benzothiazole compounds. 39. Synthesis of 3-substituted 2-phenyl-benzothiazole and 2-(2-phenylethyl)benzothiazolium salts

Čulák, V. Sutoris, A. Gáplovský, and V. Sekerka

Department of Organic Chemistry, Faculty of Natural Sciences, Comenius University, CS-842 15 Bratislava

Abstract: Trimethylsilyl ester of polyphosphoric acid was used as a cyclocondensation agent to prepare 2-phenylbenzothiazole and 2-(2-phenylethyl)benzothiazole from 2-aminothiophenol, benzoic acid, and 3-phenylpropanoic acid, respectively. Quaternary salts were prepared by alkylation of these compounds. It was proved that the electronic effect of phenyl group in 2-phenylbenzothiazole makes the course of quaternization difficult. 2-Phenyl-3-allylbenzothiazolium triiodide was isolated by treating 2-phenylben­zothiazole with an excess of allyl iodide. The structure of 3-substituted 2-phenyl- and 2-(2-phenylethyl)benzothiazolium salts was confirmed by UV and ¹H NMR spectroscopy. A high-noticeable growth-regulating activity was found for 2-[2-(4-nitrophenyl)ethyl]-3-methylbenzothiazolium iodide when tested on Triticum aestivum L.

Full paper in Portable Document Format: 445a693.pdf

Chemical Papers 44 (5) 693–702 (1990)