which starts from N,N′-dialkyl o-phenylenediamines via intramolecular dehydrogenative coupling under the oxidation of DDQ with mild conditions. Through detailed optimization of reaction conditions, only DDQ was found essential without any additives to reach to the highest yield of 99%. In the cases of linear aliphatic substituents, the synthesis of 1-alkyl-2-phenylbenzimidazoles showed high selectivities
o-phenylenediamine and carbonyl compounds by Brønstedacid/base assisted titanocene dichloride. Mechanism research including NMR and ESI-MS analyses and control experiments elucidated the new catalytic species formed by Cp2TiCl2 and the combination of titanocene Lewis acid with Brønstedacid/base was responsible for selective transformations of aldehyde and ketone with o-phenylenediamine into benzimidazole
An efficient method for the transformation of N-benzyl bisarylhydrazones and bisaryloxime ethers to functionalized 2-aryl-N-benzylbenzimidazoles and 2-arylbenzoxazoles is described. The protocol involves a copper(II)-mediated cascade C-H functionalization/C-N/C-O bond formation under neutral conditions. Substrates having either electron-donating or -withdrawing substituents undergo the cyclization to afford the target heterocycles at moderate temperature.
CHALAPATHY RAO C. V.; VEERANAGAIAH V.; REDDY K. K.; RAO N. V. S., INDIAN J. CHEM., 1980, B17, NO 6, 566-568
作者:CHALAPATHY RAO C. V.、 VEERANAGAIAH V.、 REDDY K. K.、 RAO N. V. S.
DOI:——
日期:——
REDDY, K. SUDERSHAN;RAO, C. V. CHALAPATHI, CURR. SCI., INDIA, 1984, 53, N 21, 1140-1141