Abadleh, Mohammed M. published the artcileThiophene ring-opening reactions. Direct access to the synthesis of 1,3,4-thiadiazoline-(condenced) pyridone hybrids, SDS of cas: 52431-30-8, the publication is Tetrahedron (2021), 131957, database is CAplus.
The reaction of N’-(aryl)benzothiohydrazides with 2-chloro-7-cyclopropyl-3-nitro-4-oxothieno[2,3-b]pyridine-5-carboxylic ester/acid in the presence of triethylamine furnished, upon addition of iodomethane, the resp. 1,3,4-thiadiazoline-(6-methylthio-4-oxopyridine) hybrids. Interestingly, the reaction of thiohydrazides with 4-oxothieno[2,3-b]pyridines incorporating N1-(2′-halogeno-5′-nitrophenyl) entities generated 1,3-thiazoline ring embedded in the resulting [fused]-tricyclic products. Similarly, the N1-(2′-chloropyridin-3′-yl) analog produced the resp. thiazolo[3,2-a: 5,6-b’]dipyridine-thiadiazoline hybrid. Monocyclic 2-chloro-3-nitrothiophenes in their reaction with benzothiohydrazide formed notable thiophene ring-opening products. This behavior is verified by quantum mech. calculations A proposed mechanistic pathway for this new reaction involving preferential predominance of thiophene ring-opening over Smiles rearrangement is presented.
Tetrahedron published new progress about 52431-30-8. 52431-30-8 belongs to bromides-buliding-blocks, auxiliary class Liquid Crystal &OLED Materials, name is 2,5-Dibromo-3,4-dinitrothiophene, and the molecular formula is C4Br2N2O4S, SDS of cas: 52431-30-8.
Referemce:
https://en.wikipedia.org/wiki/Bromide,
bromide – Wiktionary