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 method for p-methylbenzyl (MBn) protection of alcohols by using MBn 2,2,2-trichloroacetimidate is described. The trichloroacetimidate can easily be prepared and isolated as a stable white powder ...
Enantioselective Linchpin Catalysis by SOMO Catalysis: An Approach to the Asymmetric α-Chlorination of Aldehydes and Terminal Epoxide Formation
作者:Muriel Amatore、Teresa D. Beeson、Sean P. Brown、David W. C. MacMillan
DOI:10.1002/anie.200901855
日期:2009.6.29
Time for SOme MOre: For the first time SOMO (singly occupied molecular orbital) activation has been exploited to allow a new approach to the α‐chlorination of aldehydes. This transformation can be readily implemented as part of a linchpincatalysisapproach to the enantioselective production of terminalepoxides.
SOme MOre 时间:首次利用 SOMO(单占据分子轨道)激活来实现醛的 α-氯化的新方法。这种转化可以很容易地作为对映选择性生产末端环氧化物的关键催化方法的一部分来实现。
InCl3 immobilized in ionic liquids: a novel and recyclable catalytic system for tetrahydropyranylation and furanylation of alcohols
作者:Jhillu Singh Yadav、Basi. V. Subba Reddy、Dughani Gnaneshwar
DOI:10.1039/b210044b
日期:2003.1.20
A mild and highly efficient method has been developed for the protection of hydroxyl compounds as tetrahydropyranyl and furanyl ethers using a catalytic amount of indium trichloride immobilized in 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid under mild conditions. A wide range of functional and protecting groups such as THP, TBDMS, TBDPS, PMB, MOM ethers, acetonides, olefins and epoxides are compatible with ionic liquids. Monoprotection of diols has also been achieved using this novel procedure.
Direct and Enantioselective Organocatalytic α-Chlorination of Aldehydes
作者:Michael P. Brochu、Sean P. Brown、David W. C. MacMillan
DOI:10.1021/ja049562z
日期:2004.4.1
The first direct enantioselective catalytic α-chlorination of aldehydes has been accomplished. The use of enamine catalysis has provided a new organocatalytic strategy for the enantioselective chlorination of aldehydes to generate α-chloro aldehydes, an important chiral synthon for chemical and medicinal agent synthesis. The use of imidazolidinone 3 as the asymmetric catalyst has been found to mediate