Synthesis of benzothiazole analogs via stephen benzonitriles reductions

The Stephen reduction is a classical transformation for converting benzonitriles into benzaldehydes, typically employing concentrated hydrochloric acid (HCl) in the presence of tin(II) chloride dihydrate (SnCl2·2H2O) as the reducing system. During the reaction, tin(IV) chloride (SnCl4) is generated in situ, which plays a crucial role in facilitating the subsequent cyclization with 2-aminothiophenol, thereby enhancing the overall efficiency of the process and yielding benzothiazole. This methodology has been further adapted into a streamlined one-pot protocol, enabling the efficient synthesis of benzothiazole analogues with improved yields and operational simplicity.