Development of a novel protocol for chemoselective deprotection of N/O-benzyloxycarbonyl (Cbz) at ambient temperature
摘要:
A novel protocol for the deprotection of N-benzyloxycarbonyl and O-benzyloxycarbonyl groups by nickel boride generated in situ from NaBH4 and NiCl(2)6H(2)O in methanol at room temperature has been developed to give the corresponding amines and phenols. This protocol is chemoselective as groups like chloro, bromo, amide, ester, pyridine, and tert-butyloxycarbonyl moiety are unaffected under these conditions. The deprotection has also been validated in gram scale reactions, to establish the wider appropriateness of this protocol.
Benzyl Protection of Phenols under Neutral Conditions: Palladium-Catalyzed Benzylations of Phenols
作者:Ryoichi Kuwano、Hiroki Kusano
DOI:10.1021/ol800548t
日期:2008.5.1
Benzyl protection of phenols under neutral conditions was achieved by using a Pd(eta3-C3H5)Cp-DPEphos catalyst. The palladium catalyst efficiently converted aryl benzyl carbonates into benzyl-protected phenols through the decarboxylative etherification. Alternatively, the nucleophilic substitution of benzyl methyl carbonates with phenols proceeded in the presence of the catalyst, yielding aryl benzyl