Straightforward Reductive Esterification of Carbonyl Compounds with Carboxylic Acids through Tosylhydrazone Intermediates
作者:Angel-Humberto García-Muñoz、María Tomás-Gamasa、M. Carmen Pérez-Aguilar、Erick Cuevas-Yañez、Carlos Valdés
DOI:10.1002/ejoc.201200647
日期:2012.7
The reaction of carboxylicacids with tosylhydrazones in basic media gives rise to the corresponding esters through an O–H insertion reaction in the in situ generated diazo compound. The process is operationally very simple, catalyst free, and very general with regard to the structure of both coupling partners. In particular, the esterification can be accomplished by employing tosylhydrazones derived
and the pinacolboronates can be isolated after reaction of the benzylboronic acid with pinacol. The metholodogy has been applied to the reactions of alkylboronic acids with N-tosylhydrazones of aromaticaldehydes and ketones, and to the reactions of arylboronic acids with N-tosylhydrazones of aliphatic ketones. Moreover, the employment of the DBU/DIPEA bases combination allows for homogeneous reactions