Modulating Reactivity and Diverting Selectivity in Palladium-Catalyzed Heteroaromatic Direct Arylation Through the Use of a Chloride Activating/Blocking Group
作者:Benoît Liégault、Ivan Petrov、Serge I. Gorelsky、Keith Fagnou
DOI:10.1021/jo902515z
日期:2010.2.19
Through the introduction of an aryl chloride substituent, the selectivity of palladium-catalyzeddirectarylation may be diverted to provide alternative regioisomeric products in high yields. In cases where low reactivity is typically observed, the presence of the carbon−chlorine bond can serve to enhance reactivity and provide superior outcomes. From a strategic perspective, the C−Cl bond is easily
Continuous Flow Magnesiation of Functionalized Heterocycles and Acrylates with TMPMgCl⋅LiCl
作者:Trine P. Petersen、Matthias R. Becker、Paul Knochel
DOI:10.1002/anie.201404221
日期:2014.7.21
A flow procedure for the metalation of functionalizedheterocycles (pyridines, pyrimidines, thiophenes, and thiazoles) and various acrylates using the strong, non‐nucleophilic base TMPMgCl⋅LiCl is reported. The flow conditions allow the magnesiations to be performed under more convenient conditions than the comparable batch reactions, which often require cryogenic temperatures and long reaction times
Thiophene was regioselectively deprotonated at C2 on treatment with 1/3 equiv of Bu3MgLi in THF at room temperature. The lithium arylmagnesate formed was either trapped with electrophiles or cross-coupled in a 'one-pot' procedure with aryl halides under palladium catalysis. 2-Chlorothiophene and 2-methoxythiophene were similarly deprotonated at C5 under the same reaction conditions. The enhancement of the reactivity of the base using TMEDA was evidenced using H-1 NMR spectroscopy. (c) 2005 Elsevier Ltd. All rights reserved.