Regioselective Oxidation of 4,5-Disubstituted Pyrazoles:Controlled by Resonance Stabilization versus Hyperconjugation

摘要

DDQ (2,3-dichloro-5,6-dicyano-1,4-benzoquinone) is one of the most frequently used reagents to perform several organic transformations such as dehydrogenation or oxidation of allylic and benzylic alcohols.DDQ also has been used for the deprotection of several protecting groups from alcohols such as allyl,p-methoxybenzyl (PMB),and dimethoxy benzyl (DMB) groups.