Iodine catalyzed synthesis of 2,5-substituted oxazoles from N-arylethylamides through intramolecular C(sp3)–H functionalization under metal-free conditions is described.
Solar photo-thermochemical syntheses of 4-bromo-2,5-substituted oxazoles from N-arylethylamides
作者:Milan Dinda、Supravat Samanta、Suresh Eringathodi、Pushpito K. Ghosh
DOI:10.1039/c3ra47603k
日期:——
isolated yields were in the range 42–82%. Benzylic bromination, followed by O–C bond formation through intramolecular nucleophilic substitution, and a second benzylic bromination followed by HBr elimination, gave the oxazole ring. A third bromination of the ring yielded the final product. The feasibility of synthesizing thiazole derivatives using a similar approach was also demonstrated. During the course
Hydrolysis and alcoholysis of carboxamides derived from primary aliphatic amines were achieved under mild conditions. Amide exchange reaction between carboxamides and N1-acyl-N1, N2-di (p-nitrophenyl) formamidines (1) gave N1-acyl-N1-alkyl-N2-(p-nitrophenyl)formamidines (2) which were readily hydrolyzed or alcoholyzed to give N1-alkyl-N2-(p-nitrophenyl)formamidines (4) and carboxylic acid or its ester. Compounds 4 were hydrolyzed to give aliphatic amine and N-formyl-p-nitroaniline in the presence of acetic acid or hydrochloric acid at room temperature. For the alcoholysis of N-acyl derivatives of amino alcohols, protection of the hydroxyl substituent by an acyl group was essential because the reaction of 1 and N-acyl derivatives of amino alcohols was quite complex. Alcoholysis of N-ethyl-N, N'-ethylenebis (p-chlorobenzamide) (8a) by this method gave N-(2-aminoethyl)-N-ethyl-p-chlorobenzamide (8b). Thus, the selective alcoholysis of diacyl derivative of diamines, which contain primary and secondary amino groups, was achieved.