共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
Matthew N. Pennell Dr. Peter G. Turner Dr. Tom D. Sheppard 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(15):4748-4758
A wide range of primary, secondary and tertiary propargylic alcohols undergo a Meyer–Schuster rearrangement to give enones at room temperature in the presence of a gold(I) catalyst and small quantities of MeOH or 4‐methoxyphenylboronic acid. The syntheses of the enone natural products isoegomaketone and daphenone were achieved using this reaction as the key step. The rearrangement of primary propargylic alcohols can readily be combined in a one‐pot procedure with the addition of a nucleophile to the resulting terminal enone, to give β‐aryl, β‐alkoxy, β‐amino or β‐sulfido ketones. Propargylic alcohols bearing an adjacent electron‐rich aryl group can also undergo silver‐catalyzed substitution of the alcohol with oxygen, nitrogen and carbon nucleophiles. This latter reaction was initially observed with a batch of gold catalyst that was probably contaminated with small quantities of silver salt. 相似文献
3.
4.
Zhizhong Wang Yongjuan Chang Xinxin Gong Liyi Dai 《International journal of quantum chemistry》2012,112(3):647-652
Meyer–Schuster rearrangements of 2‐phenyl‐3‐butyn‐2‐ol with H3O+ and (H2O)6 model in high‐temperature water (HTW) have been investigated by the use of density functional theory calculations. In the substrate 2‐phenyl‐3‐butyn‐2‐ol catalyzed by H3O+ and (H2O)6, the Meyer–Schuster rearrangements were predicted by the frontier molecular orbital theory. The results show that the rearrangement does not involve the carbonium ion intermediates, but the first transition state is carboniumion like. Dehydration and hydration may occur via the intermolecular proton relay along the hydrogen‐bond chains and the second step of reaction path is a total acid–base catalytic process. Based on the results, a model considered both HTW ambient and water molecules are proposed to represent mechanisms of other reactions in HTW. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011 相似文献
5.
6.
Mannepalli Lakshmi Kantam Vura Bala Subrahmanyam Kota Balaji Shiva Kumar Gopaladasu T. Venkanna Bojja Sreedhar 《Helvetica chimica acta》2008,91(10):1947-1953
Rhodium fluoroapatite (RhFAP) is an efficient catalyst for conjugate addition of organoboron reagents to α,β‐unsaturated carbonyl compounds. A variety of arylboronic acids and α,β‐unsaturated carbonyl compounds were converted to the corresponding conjugate‐addition products, demonstrating the versatility of the reaction. The reaction is highly selective. RhFAP was recovered quantitatively by simple filtration, and reused for four cycles. 相似文献
7.
Synthesis of Phenanthrene Derivatives through the Reaction of an α,α‐Dicyanoolefin with α,β‐Unsaturated Carbonyl Compounds 下载免费PDF全文
Abdolali Alizadeh Seyed Yasub Hosseini Hadi Sedighian Fahimeh Bayat 《Helvetica chimica acta》2015,98(10):1426-1434
Phenanthrene derivatives were prepared by reacting an α,α‐dicyanoolefin with different α,β‐unsaturated carbonyl compounds resulting from Wittig reaction of ninhydrin and phosphanylidene or condensation of barbituric acid and an aldehyde. The easy procedure, mild and metal‐catalyst free, reaction conditions, good yields, and no need for chromatographic purifications are important features of this protocol. The structures of the product of type 3 and 5 were corroborated spectroscopically (IR, 1H‐ and 13C‐NMR, and EI‐MS). A plausible mechanism for this type of reaction is proposed (Scheme 1). 相似文献
8.
Andrew R. Shaffer Joseph A. R. Schmidt Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(11):2662-2673
Phorteen phine phosphines : Fourteen new α,β‐unsaturated β‐chloroimines were synthesized from inexpensive ketones by using the Vilsmeier–Haack reagent followed by Schiff‐base condensation. Each imine was subsequently converted to an α,β‐unsaturated 3‐iminophosphine through either late‐metal‐catalyzed phosphorus–carbon cross‐coupling or through an addition–elimination sequence (see scheme). This high‐yield protocol serves as a general means to produce α,β‐unsaturated 3‐iminophosphines.
9.
The readily accessible α-diazo carbonyl compounds are distinguished by their high reactivity, which opens up a variety of preparative applications under modified conditions. Wolff rearrangements of these compounds, induced thermally, photochemically, or catalytically, afford ketenes. Free and complexed carbenes, 1,3-dipoles, 1,3-diradicals, and the antiaromatic oxirenes have been considered as intermediates or transition states. The present progress report attempts to integrate preparative and theoretical aspects. 相似文献
10.
Tandem Pd/Au‐Catalyzed Route to α‐Sulfenylated Carbonyl Compounds from Terminal Propargylic Alcohols and Thiols 下载免费PDF全文
Dr. Srijit Biswas Rahul A. Watile Prof. Dr. Joseph S. M. Samec 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(8):2159-2163
An efficient and highly atom‐economical tandem Pd/Au‐catalyzed route to α‐sulfenylated carbonyl compounds from terminal propargylic alcohols and thiols has been developed. This one‐step procedure has a wide substrate scope with respect to substituents at the α‐position of the alcohol. Both aromatic and aliphatic thiols generated the α‐sulfenylated carbonyl products in good to excellent yields. A mechanism is proposed in which the reaction proceeds through a Pd‐catalyzed regioselective hydrothiolation at the terminal triple bond of the propargyl alcohol followed by an Au‐catalyzed 1,2‐hydride migration. 相似文献
11.
12.
13.
Dr. Jun‐ichi Ito Kohei Fujii Prof. Dr. Hisao Nishiyama 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(2):601-605
NCN‐pincer Ru‐complexes containing bis(oxazolinyl)phenyl ligands serve as suitable catalysts in the direct conjugate additions of α,β‐unsaturated carbonyl compounds, including ketones, esters, and amides, as well as vinylphosphonates, giving various β‐alkynyl carbonyl and phosphonate compounds. A bis(oxazolinyl)phenyl (phebox)–Ru complex also catalyzes the asymmetric conjugate addition of an alkyne with a β‐substituted, α,β‐unsaturated ketone to produce a chiral β‐alkynyl ketone. 相似文献
14.
15.
16.
17.
[3+2] Cycloaddition of Propargylic Alcohols and α‐Oxo Ketene Dithioacetals: Synthesis of Functionalized Cyclopentadienes and Further Application in a Diels–Alder Reaction 下载免费PDF全文
Zhongxue Fang Jianquan Liu Prof. Qun Liu Prof. Xihe Bi 《Angewandte Chemie (International ed. in English)》2014,53(28):7209-7213
Cyclopentadienes are valuable intermediates in organic synthesis and also ubiquitous as the Cp ligands in organometallic chemistry. As part of ongoing efforts to develop novel organic reactions that employ functionalized alkynes, a [3+2] cycloaddition of propargylic alcohols and ketene dithioacetals has been developed, which leads to fully substituted 2,5‐dialkylthio cyclopentadienes in good to excellent yields. In an unusual dethiolating Diels–Alder reaction, the cyclopentadienes were further reacted with maleimides to afford a family of novel fluorescent polycyclic compounds. 相似文献
18.
4‐Benzamido‐TEMPO catalyzed oxidation system for conversion of a wide range of alcohols to the aldehydes or ketones with NaBrO3 under room temperature conditions has been developed. The credible, operationally convenient and economical, and condition mild oxidation protocol is particularly of interest in laboratory and in fine chemicals manufacture. 相似文献
19.
We report a new, effective and simple method for preparing α,β‐unsaturated carbonyl compounds by reacting ketones and aromatic alcohols at 56°C in the presence of CrO3 (CrO3 acts as an oxidant and also a catalyst) for around 10 h. The condensation reactions occurred effectively among a wide combination of ketones and alcohols. The procedure is simple and the yields can be high up to 98%. And a probable mechanism is proposed. 相似文献