Direct and safe one-pot synthesis of functionalized dimethyl 1-aryl-1,9a-dihydropyrido[2,1-c][1,4]thiazine-1-phosphonates

A visible-light-induced direct and safe synthesis of functionalized dimethyl 1-aryl-1,9a-dihydropyrido [2,1-c][1,4]thiazine-1-phosphonates is realized from dimethyl (aryl(2-tosylhydrazono)methyl)phosphonates and pyridinium 1,4-zwitterionic thiolates with cesium carbonate as base in dichloromethane. The reaction involves the carbene generation from dimethyl (aryl(2-tosylhydrazono)methyl)phosphonates in the presence of cesium carbonate as base and the [1+5] annulation of the carbenes with pyridinium 1,4-zwitterionic thiolates to synthesize functionalized 1,9a-dihydropyrido[2,1-c][1,4]thiazine derivatives. The method avoids preparing, storing, and using potentially dangerous phosphoryl diazo compounds and features simple, convenient, catalyst-free, and mild reaction conditions.(c) 2023 Elsevier Ltd. All rights reserved.