Synthesis of Highly Substituted γ-Butyrolactones by a Gold-Catalyzed Cascade Reaction of Benzyl Esters
作者:Maria Camila Blanco Jaimes、Alexander Ahrens、Daniel Pflästerer、Matthias Rudolph、A. Stephen K. Hashmi
DOI:10.1002/chem.201402524
日期:2015.1.2
3‐butynoic acids in a gold‐catalyzed cyclization/rearrangement cascadereaction provided 3‐propargyl γ‐butyrolactones with the alkene and the carbonyl group not being conjugated. Crossover experiments showed that the formation of the new CC bond is an intermolecular process. Initially propargylic–benzylic esters were used, but alkyl‐substituted benzylic esters worked equally well. In the case of the propargylic–benzylic
Rh(III)-Catalyzed and Solvent-Controlled Chemoselective Synthesis of Chalcone and Benzofuran Frameworks via Synergistic Dual Directing Groups Enabled Regioselective C–H Functionalization: A Combined Experimental and Computational Study
between the hydroxyl group and the Rh(III) catalyst play a decisive role in promoting the regioselective migratory insertion of the alkyne moiety. Thereafter, two solvent-controlled switchable reaction pathways, which respectively involvetandem β–H elimination/hydrogen transfer/oxidative addition/C–O bond reductive elimination/oxidation (for low-polar solvents: path I–Ia via a RhIII–RhI–RhIII pathway)
借助协同双指导基团(O–NHAc部分和羟基)辅助策略,有效和实用的Rh(III)催化的区域选择性氧化还原中性C–H功能化了多种N已经实现了具有炔丙醇的β-苯氧基乙酰胺,其导致以溶剂控制的化学选择性方式多样化地合成了优先的苯并呋喃和查尔酮骨架。实验和计算研究表明,双指导基团之间氢键的形成以及随后的羟基与Rh(III)催化剂之间的配位相互作用在促进炔烃部分的区域选择性迁移插入中起决定性作用。此后,二溶剂控制的切换的反应途径,其分别涉及串联β-H消除/氢转移/氧化加成/ C-O键还原消除/氧化(低极性溶剂:路径我-我一个经由铑III -铑我-Rh III途径)和氧化加成/β-H消除/氢转移/质子分解(用于高极性溶剂:路径II - II b经由铑III -Rh V -Rh III途径),后跟提供相应的化学选择性优异的产品。综上所述,我们在此给出的结果不仅扩展了O-NHAc定向的C-H活化的范围,而
Rh(I)-Catalyzed Transformation of Propargyl Vinyl Ethers into (<i>E</i>,<i>Z</i>)-Dienals: Stereoelectronic Role of <i>trans</i> Effect in a Metal-Mediated Pericyclic Process and a Shift from Homogeneous to Heterogeneous Catalysis During a One-Pot Reaction
作者:Dinesh V. Vidhani、Marie E. Krafft、Igor V. Alabugin
DOI:10.1021/jo402505f
日期:2014.1.3
experiments and computations reveals unusual features of stereoselective Rh(I)-catalyzed transformation of propargyl vinylethers into (E,Z)-dienals. The first step, the conversion of propargyl vinylethers into allene aldehydes, proceeds under homogeneous conditions via a “cyclization-mediated” mechanism initiated by Rh(I) coordination at the alkyne. This path agrees well with the small experimental
Stereocontrolled Synthesis of (<i>E,Z</i>)-Dienals <i>via</i> Tandem Rh(I)-Catalyzed Rearrangement of Propargyl Vinyl Ethers
作者:Dinesh V. Vidhani、Marie E. Krafft、Igor V. Alabugin
DOI:10.1021/ol4019985
日期:2013.9.6
A novel Rh(I)-catalyzed approach to functionalized (E,Z) dienals has been developed viatandem transformation where a stereoselective hydrogen transfer follows a propargyl Claisen rearrangement. Z-Stereochemistry of the first double bond suggests the involvement of a six-membered cyclic intermediate whereas the E-stereochemistry of the second double bond stems from the subsequent protodemetalation
Gold catalyzed intramolecular hydroalkoxylation assisted ring opening of furans to the corresponding saturated γ-keto esters
作者:Chinta Nagaraju、Kavirayani R. Prasad
DOI:10.1016/j.tet.2015.10.017
日期:2015.12
A facile ring opening of furans in furyl propargyl alcohols to the corresponding saturated γ-keto esters is observed in the gold(III) chloride catalyzed reaction with MeOH. It is found that the ring opening of furan is driven by the intramolecular hydroalkoxylation. Mitigating the intramolecular hydroalkoxylation led to the expected conjugated enyne resulting from the dehydration.