RESUMO
A facile and effective method for Rh-catalyzed direct ortho-alkylation of C-H bonds in (hetero)arenes with commercially available carboxylic acids has been developed. This strategy was initiated by in situ conversion of carboxylic acids to anhydrides which, without isolation, underwent Rh-catalyzed direct decarbonylative cross-coupling of aryl carboxamides containing 8-aminoquinoline. The reaction proceeds with high regioselectivity and exhibits a broad substrate scope as well as functional group tolerance.
RESUMO
A telescoping process involving the consecutive addition of four reagents (trifluorodiazoethane, phosphine, allenyl ester, and acetic acid) into a single reactor was developed for the novel functionalization of allenyl esters. First, new phosphazenes derived from trifluorodiazoethane and phosphines were generated and reacted with allenyl esters to give unexpected α-iminophosphoranes through the creation of C=P, C=N, and C-H bonds at the α-, ß-, and γ-carbon atoms, respectively, of the allenyl esters. The α-iminophosphoranes did not react with aldehydes in a classic Wittig reaction, but instead ß-enamino esters were obtained. The overall sequence of reactions offered a formal hydrohydrazonation of allenyl esters. The method was extended to other related diazo compounds and applied to the preparation of novel 5-pyrazolone derivatives. Not only is the telescoping process described herein an effective approach for truncating the multistep synthesis, but also each step has been dissected to understand and support the reaction mechanisms.
