Rapid Chemoselective Deprotection of Benzyl Esters by Nickel Boride
作者:Jitender Khurana、Reema Arora
DOI:10.1055/s-0028-1087982
日期:2009.4
Benzyl esters of a variety of acids can be chemoselectively cleaved on treatment with nickel boride in methanol at ambient temperature to give the parent carboxylic acids in high yields. Other protecting functionalities such as methyl, ethyl, tert-butyl, and trityl esters as well as benzyl ethers, tert-butyl ethers, and N-benzylamides are unaffected under these conditions.
Pt-Catalyzed sp3 C–H bond activation of o-alkyl substituted aromatic carboxylic acid derivatives for the formation of aryl lactones
作者:Ji Min Lee、Sukbok Chang
DOI:10.1016/j.tetlet.2005.12.104
日期:2006.2
Synthesis of aryl lactones from ortho-alkyl substituted aromatic carboxylic acids is described on the basis of sp3 C–H bond activation using either palladium or platinum catalysts. Kinetic isotope studies reveal that the reaction takes place presumably by the chelation assistance of metal catalyst to the carboxylic group followed by the C–H bond activation.
Abstract A new efficient and selectiveesterification reaction of carboxylic acids with chloroformates is described using silica-supported catalyst (PBGSiCl). The chemioselectivity of the reaction was high particularly for sterically hindered carboxylic acids supported by a single pathway reaction.
A metal‐free oxidative esterification or thio‐esterification of readily available substituted malononitrile and alcohol or thiol has been developed by simply mixing α‐substituted malononitrile and alcohol or thiol in the presence of base under a molecular oxygen atmosphere.
The reaction of 2-chloro-3,5-dinitropyridine (CDNP) with carboxylic acids and alcohols was examined, and it was found that CDNP was a useful condensingagent. Various esters were prepared in good yields.