Facile and Selective Deallylation of Allyl Ethers Using Diphosphinidenecyclobutene-Coordinated Palladium Catalysts
摘要:
(pi-Allyl)palladium triflate bearing a 1,2-bis(4-methoxyphenyl)-3,4-bis(2,4,6-tri-tert-butylphenylphosphinidene)cyclobutene ligand (DPCB-OMe), [Pd(eta(3)-C3H5)(DPCB-OMe)]OTf, efficiently catalyzes deallylation of a variety of allyl ethers in aniline to give corresponding alcohols in high yields under mild conditions. The reactions can be performed in air without loss of a variety of functionalities including vinyl, alkynyl, hydroxy, acetoxy, silyloxy, and acetal groups. Allyl 2-allyloxybenzoate selectively undergoes deallylation of the allyloxy group to give allyl salicylate in quantitative yield.
Allyl deprotection to liberate free hydroxy, amino and acid groups from the corresponding allylethers, amines and esters is achieved under mild conditions. The reagent combination employed for this transformation is polymethylhydrosiloxane (PMHS), ZnCl2 and Pd(PPh3)4.
A facile and catalytic method for selective deprotection of tert-butyldimethylsilyl ethers with copper(II) bromide
作者:Suchitra Bhatt、Sandip K. Nayak
DOI:10.1016/j.tetlet.2006.09.073
日期:2006.11
Copper(H) bromide is found to be a simple and efficient catalyst for selective deprotection of tert-butyidimethylsilyl ethers of alcohols/phenols at ambient temperature. Various labile functional groups such as ketal, alkene, ketone, OTBDPS, OTHP and allyl and benzyl ethers are found to be compatible under the reaction conditions. (c) 2006 Elsevier Ltd. All rights reserved.