Syntheses of heterocyclic fused thiazolecarboxylic acids I

Abstract

A number of thiazolo 5‐carboxylic acid derivatives were prepared which were fused to other heterocycles such as 1,2,4‐benzothiadiazine, quinazoline, and pyrimidine rings at the 2,3‐position of the thiazole ring. In several instances unexpected products were obtained, depending on the reaction conditions. The chemistry of these reactions and the identification of the products are discussed.

The Chemistry of Thiophosgene

“…(291), obtained by reaction of the corresponding oximes with sodium hydride, may be allowed to react with thiophosgene to give the respective oximethiocarbonyl chlorides (29.2) which on treatment with secondary amines or sodium azide afford the oximethiocarbamates TilE CHEMISTRY OF TIUOPHOSGENE ss may be allowed to react with another equivalent of thiol to form trithiocarbonates (296). 462 -466 Addition of thiophosgene to a suspension of the sodium salt of 2-mercaptobenzothiazole (297) in ether resuits predominantly in S-acylation to give bis-(2-benzothiazolyl) trithiocarbonate (298) in 88% yield 467 while the chlorothioformate (2~9b), prepared from methyl3-mercaptopropionate (299a) and thiophosgene, reacts wi~h diazomethane to afford the isomeric thiadiazoles 300 and 30J4 68 (Scheme 83). …”

One-Step Synthesis of 2-Chloropyrimidin-4-ol Derivatives: An Unusual Reactivity of Thiophosgene

“…The initial reaction conditions were optimized based on the procedure used by Gochman and Wei starting from anthranilamide and thiophosgene . The authors described the formation of 2-thiopyrimidin-4-ol 4 and a tetracyclic byproduct 5 , exclusively.…”