1975-51-5, Name is 2-Methyl-4-nitrobenzoic acid, molecular formula is C8H7NO4, SDS of cas: 1975-51-5, belongs to isothiazole compound, is a common compound. In a patnet, author is Duan, XG, once mentioned the new application about 1975-51-5.
Conversion of pyrroles into bi-1,2,5-thiadiazoles: a new route to biheterocycles
Trithiazyl trichloride 1 converts 1,2,5-triphenylpyrrole 5 into its 3,4-dichloro derivative together with the isothiazole imine 6 and the imine hydrolysis product, the ketone 3. The best yield of the isothiazole 6 is obtained in the presence of 4 Angstrom molecular sieves (Table 1). Conversion of the pyrrole 5 into the isothiazole 6 is exactly analogous to the reaction of 1 with 2,5-diphenyl-furan and -thiophene. Other N-aryl and the related 2,5-diphenylpyrroles 8 give similar results (Table 2). However, 1-methyl-2,5-diphenylpyrrole 11 reacts with 1 in an entirely different way to give 4,4′-diphenyl-3,3′-bi-1,2,5-thiadiazole 12, in which two thiadiazole rings have been fused onto the pyrrole and the CH3N unit has been excised as HCN. The same product 12 is formed, In similar yields, by reaction of 1 with 1,4-diphenylbuta-1,3-diyne and 1,4-diphenylbut-1-en-3-yne. Other N-alkyl 2,5-diphenylpyrroles 16 react similarly (Table 3), giving the best yield (70%) of bi-thiadiazole 12 in the presence of 4 Angstrom molecular sieves (Table 4). 1-Methyl- and 1-ethyl-3,4-dibromo-2,5-diphenylpyrrole also give 12, together with 3-(benzoyldichloromethyl)-4-phenyl-1,2,5-thiadiazole 21 in high combined yield. The formation of bi-1,2,5-thiadiazole 12 from N-alkylpyrroles represents a new dissection of the pyrrole ring and a new and very short route to an aromatic biheterocyclic system. Mechanisms which rationalise the different pathways observed are proposed for all of these reactions.
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Reference:
Isothiazole – Wikipedia,
,Isothiazole – ScienceDirect.com