Expedient Access to 2,3-Dihydropyridines from Unsaturated Oximes by Rh(III)-Catalyzed C–H Activation
摘要:
alpha,beta-Unsaturated - oxime pivalates are proposed to undergo reversible C(sp(2))-H insertion with cationic Rh (III) complexes to furnish five-membered metallacycles. In the presence of 1,1-disubstituted olefins, these species participate in irreversible migratory insertion to give, after reductive elimination, 2,3-dihydropyridine products in good yields. Catalytic hydrogenation can then be used to. convert these molecules into piperidines, which are important structural components of numerous pharmaceuticals.
A general strategy for the hydroalkylation of vinyl ketones using ethers catalyzed by an iron catalyst is described. This catalytic method permits direct transformation of easily accessible and abundant precursors into highly substituted, structurally diverse and functionally concentrated products.
New Metal-Free One-Pot Synthesis of Substituted Allenes from Enones
作者:Meng Tang、Chun-An Fan、Fu-Min Zhang、Yong-Qiang Tu、Wen-Xue Zhang、Ai-Xia Wang
DOI:10.1021/ol802445p
日期:2008.12.18
A new metal-free, one-pot synthesis of substituted allenes from enones was discovered for the first time, in which a tertiary amine as a base was found to be an effective promoter in such novel transformations. The present synthetic protocol proceeded readily with high compatibility of sensitive functional groups, and it provides a new efficient way to access a series of synthetically important allenes
Brønsted Base-Catalyzed Transformation of α,β-Epoxyketones Utilizing [1,2]-Phospha-Brook Rearrangement for the Synthesis of Allylic Alcohols Having a Tetrasubstituted Alkene Moiety
stereoselective transformation of α,β-epoxyketones into alkenylphosphates having a hydroxymethyl group on the β-carbon was established by utilizing the [1,2]-phospha-Brook rearrangement under Brønsted base catalysis. The reaction involves the catalytic generation of an α-oxygenated carbanion located at the α-position of an epoxide moiety through the [1,2]-phospha-Brook rearrangement and the following
Transition-Metal-Free Homologative Cross-Coupling of Aldehydes and Ketones with Geminal Bis(boron) Compounds
作者:Thomas C. Stephens、Graham Pattison
DOI:10.1021/acs.orglett.7b01474
日期:2017.7.7
We report a transition-metal-free coupling of aldehydes and ketones with geminal bis(boron) building blocks which provides the coupled, homologated carbonyl compound upon oxidation. This reaction not only extends an alkyl chain containing a carbonyl group, it also simultaneously introduces a new carbonyl substituent. We demonstrate that enantiopure aldehydes with an enolizable stereogenic center undergo
Development of an Anomalous Heck Reaction: Skeletal Rearrangement of Divinyl and Enyne Carbinols
作者:J. Maina Ndungu、Kimberly K. Larson、Richmond Sarpong
DOI:10.1021/ol052382p
日期:2005.12.1
[reaction: see text] A general set of conditions that achieves the union of aryl halides and divinyl or enyne carbinols to afford tri- or tetrasubstituted olefins in good yields (up to 83%) is described. The mechanism by which this proceeds is believed to involve the intermediacy of a cyclopropanol, followed by a novel skeletal reorganization. The ability to suppress beta-hydride elimination of organopalladium