Controlling chemoselective transformations of 4-acylpyridines via a Pd–C catalytic hydrodechlorination–hydrogenation
摘要:
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 alpha-alkyl-4-piperidinemethanol hydrochlorides, respectively. This catalytic method was performed simply by an addition of 1 equiv of CICH2CHCl2 to the conventional hydrogenation system and directly gave the crystalline piperidine hydrochlorides in practical quantitative yields. (C) 2013 Elsevier Ltd. All rights reserved.
Comparative inhibition of tetrameric carbonyl reductase activity in pig heart cytosol by alkyl 4-pyridyl ketones
摘要:
Context and objective: The present study is to elucidate the comparative inhibition of tetrameric carbonyl reductase (TCBR) activity by alkyl 4-pyridyl ketones, and to characterize its substrate-binding domain.Materials and methods: The inhibitory effects of alkyl 4-pyridyl ketones on the stereoselective reduction of 4-benzoylpyridine (4-BP) catalyzed by TCBR were examined in the cytosolic fraction of pig heart.Results: Of alkyl 4-pyridyl ketones, 4-hexanoylpyridine, which has a straight-chain alkyl group of five carbon atoms, inhibited most potently TCBR activity and was a competitive inhibitor. Furthermore, cyclohexyl pentyl ketone, which is substituted by cyclohexyl group instead of phenyl group of hexanophenone, had much lower ability to be reduced than hexanophenone.Discussion and conclusion: These results suggest that in addition to a hydrophobic cleft corresponding to a straight-chain alkyl group of five carbon atoms, a hydrophobic pocket with affinity for an aromatic group is located in the substrate-binding domain of TCBR.
Steric effects ih the reaction of di(bromomagnesio)alkanes with carboxylic esters
作者:Perséphone Canonne、Denis Bélanger、Gilles Lemay
DOI:10.1016/s0040-4039(01)92402-5
日期:1981.1
Largely different product distributions were observed on the action of various carboxylic esters with 1,4-di(bromomagnesio)butane and its homologue 1,5-di(bromomagnesio)pentane. The much larger yields of reduction product with the latter are the evidence for the structural geometric requirements for the annelation step.
n-Butyllithium at -78degreesC readily abstracts the methine proton from the title compound. The anion reacts efficiently with a range of electrophiles to provide 4-pyridyl ketones upon acid hydrolysis.
Hydroacylation of 1-Alkene with Heteroaromatic Aldehyde by Rh(I) and Additives
作者:Chul-Ho Jun、Dae-Yon Lee、Jun-Bae Hong
DOI:10.1016/s0040-4039(97)01562-1
日期:1997.9
Hydroacylation of 1-alkene with a heteroaromatic aldehyde such as pyridinecarboxaldehyde, thiophenecarboxaldehyde and furfural derivatives under cocatalyst of Wilkinson's complex and 2-amino-3-picoline gave poor yield of hydroacylated product. The addition of a catalytic amount of his(cyclopentadienyl)zirconium dichloride or bis(cyclopentadienyl)titanium dichloride as an additive dramatically increased the yield of the hydroacylated ketone product. (C) 1997 Elsevier Science Ltd.