Controlling chemoselective transformations of 4-acylpyridines via a Pd-C catalytic hydrodechlorination-hydrogenation
A novel Pd-C catalytic hydrodechlorination-hydrogenation was developed for a multi-step one-pot transformation of 4-acylpyridines. Under the selected conditions, 4-benzoylpyridines and 4-alkanoylpyridines were chemoselectively converted into the corresponding 4-benzylpiperidine hydrochlorides and α-alkyl-4-piperidinemethanol hydrochlorides, respectively. This catalytic method was performed simply by an addition of 1 equiv of ClCH 2CHCl2 to the conventional hydrogenation system and directly gave the crystalline piperidine hydrochlorides in practical quantitative yields.
Hydroxymethylations of aryl halides by Pd-catalyzed cross-couplings with (benzoyloxy)methylzinc iodide - Scope and limitations of the reaction
Palladium-catalyzed cross-coupling reactions of (benzoyloxymethyl)zinc iodide with diverse (het)aryl halides leading to (benzoyloxymethyl)(het)arenes were studied to define the scope of this reaction. It has been found that this reaction is only applicable for electron-deficient aryl halides and the most efficient it is for 2-halopyridines and 4-halopyrimidines. Deprotection of the intermediates gives (hydroxymethyl)pyridines and -pyrimidines in high yields. Georg Thieme Verlag Stuttgart.
Hasník, Zbyněk,?ilhár, Peter,Hocek, Michal
p. 543 - 546
(2008/12/22)
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