共查询到20条相似文献,搜索用时 15 毫秒
1.
A Ph3P‐catalyzed cyclization of α‐halogeno ketones 2 with dialkyl acetylenedicarboxylates (=dialkyl but‐2‐ynedioates) 3 produced halogenated α,β‐unsaturated γ‐butyrolactone derivatives 4 in good yields (Scheme 1, Table). The presence of electron‐withdrawing groups such as halogen atoms at the α‐position of the ketones was necessary in this reaction. Cyclization of α‐chloro ketones resulted in higher yields than that of the corresponding α‐bromo ketones. Dihalogeno ketones similarly afforded the expected γ‐butyrolactone derivatives in high yields. 相似文献
2.
3.
Kazuhiro Kobayashi Kenichi Hashimoto Hiroo Hashimoto Hideaki Kondo Hisatoshi Konishi 《Helvetica chimica acta》2011,94(7):1277-1282
A novel method is reported for the synthesis of 9,9‐disubstituted 9H‐pyrrolo[1,2‐a]indoles. Cyclization of 1‐[2‐(1‐aryl(or methyl)ethenyl)phenyl]‐1H‐pyrroles, which can be easily prepared from 2‐(1‐aryl(or methyl)ethenyl)anilines, proceeds smoothly, in general, at 0° in the presence of a catalytic (or an equimolar) amount of HI in MeCN to provide the desired products. 相似文献
4.
Johannes Schranck Mia Burhardt Christoph Bornschein Dr. Helfried Neumann Prof. Dr. Troels Skrydstrup Prof. Dr. Matthias Beller 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(31):9534-9538
A carbonylative α‐arylation process employing unactivated nitriles for the first time is described. The reaction tolerates a range of (hetero)aryl iodides and several nitrile coupling partners. No prefunctionalization of the nitriles is necessary and the resulting β‐ketonitriles are obtained in good to excellent yields. The methodology also allows for a convenient 13C‐labelling of the generated carbonyl moiety. 相似文献
5.
Afsaneh Feiz Ghazaleh Imani Shakibaei Zahra Yasaei Hamid Reza Khavasi Ayoob Bazgir 《Helvetica chimica acta》2011,94(9):1628-1637
A new four‐component synthesis of spiro[4H‐indeno[1,2‐b]pyridine‐4,3′‐[3H]indoles] and spiro[acenaphthylene‐1(2H),4′‐[4H‐indeno[1,2‐b]pyridines] by the reaction of indane‐1,3‐dione, 1,3‐dicarbonyl compounds, isatins (=1H‐indole‐2,3‐diones) or acenaphthylene‐1,2‐dione, and AcONH4 in refluxing toluene in the presence of a catalytic amount of pyridine is reported. 相似文献
6.
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
7.
A series of α‐(fluoro‐substituted phenyl)pyridines have been synthesized by means of a palladium‐catalyzed cross‐coupling reaction between fluoro‐substituted phenylboronic acid and 2‐bromopyridine or its derivatives. The reactivities of the phenylboronic acids containing di‐ and tri‐fluoro substituents with α‐pyridyl bromide were investigated in different catalyst systems. Unsuccessful results were observed in the Pd/C and PPh3 catalyst system due to phenylboronic acid containing electron‐withdrawing F atom(s). For the catalyst system of Pd(OAc)2/PPh3, the reactions gave moderate yields of 55% –80%, meanwhile, affording 10% –20% of dimerisation (self‐coupling) by‐products, but trace products were obtained in coupling with 2,4‐difluorophenylboronic acids because of steric hinderance. Pd(PPh3)4 was more reactive for boronic acids with sterically hindering F atom(s), and the coupling reactions gave good yields of 90% and 91% without any self‐coupling by‐product. 相似文献
8.
9.
10.
11.
12.
Koosam Mahendar A. V. S. Sarma P. Raghavaiah Mannepalli Lakshmi Kantam Kenneth J. Klabunde 《Helvetica chimica acta》2011,94(8):1533-1542
Aldol‐type reaction between electron deficient aldehydes and sulfonium salts to afford the corresponding β‐hydroxy α‐sulfanyl esters in moderate‐to‐good yields by using nanocrystalline MgO is described. The sulfanyl group is a useful group for further transformations in organic synthesis. Low Rf‐value isomer is anti‐configured as revealed by X‐ray diffraction study and consistent with the assignment of 1H‐NMR spectrum. 相似文献
13.
The [Cu(acac)2]‐catalyzed reactions of α,β‐unsaturated carboxamides with dimethyl diazomalonate yielded dihydrofuran derivatives by a 1,5‐electrocyclic reaction at C(β), and butadiene derivatives by carbene addition reaction at C(α) (Schemes 4 and 5; Table). Phenyl substituents at the N‐atom of the amides seem to be effective on the reaction pathways (Table). 相似文献
14.
A novel ‘click ligation’ strategy for the stereoselective synthesis of a medium‐size library of structurally complex and functionally diverse oxazolone peptidomimetics, which contain α‐acylamino carboxamide or β‐amido ketone residues, is presented. Most of these molecules have lipophilicity constant values (log P) in the qualifying range for cell permeability, and that indicates the possibilities of these new molecules to be used in the search for potential inhibitors for a broad spectrum of enzymes. 相似文献
15.
Kodai Kato Prof. Dr. Koji Hirano Prof. Dr. Masahiro Miura 《Angewandte Chemie (International ed. in English)》2016,55(46):14400-14404
A copper‐catalyzed regioselective and stereospecific aminoboration of vinylsilanes with bis(pinacolato)diboron (pinB‐Bpin) and hydroxylamines has been developed. In the presence of a CuCl/MeO‐dppbz catalyst, the boryl group and amino group are incorporated at the β position and α position, respectively, and the corresponding β‐boryl‐α‐aminosilanes are obtained with good diastereoselectivity. The boryl group is a good latent functional group, and subsequent manipulations provide a variety of β‐functionalized α‐aminosilanes of great potential in medicinal chemistry. Additionally, preliminary application to asymmetric catalysis is also described. 相似文献
16.
The novel 1,2‐diaryl substituted pyrrolo[3,4‐b]pyridine‐5,7‐diones were selectively synthesized in high yields by the base catalyzed cyclization reaction of 3‐arylamino‐1‐methyl‐1H‐pyrrole‐2,5‐diones with cinnamaldehyde and its derivatives in acetonitrile at room temperature. However, when piperidinium trifluoroacetate was employed as catalyst, the reaction afforded a mixture of 1,2‐diaryl and 1,4‐diaryl substituted pyrrolo[3,4‐b]pyridine‐5,7‐diones in comparable yields. 相似文献
17.
18.
Ya‐Li Chang Chi‐Lin Chung Fang‐Wen Wu Huey‐Min Wang Rei‐Sheu Hou Iou‐Jiun Kang Ling‐Ching Chen 《中国化学会会志》2010,57(2):149-152
Iodobenzene‐catalyzed synthesis of α‐azidoketones and α‐thiocyanatoketones from aryl ketones with MCPBA as a cooxidant is described. The method is simple, rapid and practical, generating α‐azidoketones and α‐thiocyanatoketones from the aryl ketone without isolation of α‐tosyloxyketones in good to excellent yields. 相似文献
19.
A novel method for the asymmetric synthesis of α,β‐diamino acids by using the 2,3,4,6‐tetra‐O‐pivaloyl‐β‐D ‐glucopyranosyl group (Piv4Glc) as chiral auxiliary was developed (Table and Scheme). The reaction was promoted by CuBr?Me2S as Lewis acid, and high yields and good diastereoselectivities were achieved. 相似文献
20.
Catalytic Asymmetric Intramolecular Homologation of Ketones with α‐Diazoesters: Synthesis of Cyclic α‐Aryl/Alkyl β‐Ketoesters 下载免费PDF全文
Dr. Wei Li Fei Tan Xiaoyu Hao Gang Wang Yu Tang Prof. Dr. Xiaohua Liu Dr. Lili Lin Prof. Dr. Xiaoming Feng 《Angewandte Chemie (International ed. in English)》2015,54(5):1608-1611
A catalytic asymmetric intramolecular homologation of simple ketones with α‐diazoesters was firstly accomplished with a chiral N,N′‐dioxide–Sc(OTf)3 complex. This method provides an efficient access to chiral cyclic α‐aryl/alkyl β‐ketoesters containing an all‐carbon quaternary stereocenter. Under mild conditions, a variety of aryl‐ and alkyl‐substituted ketone groups reacted with α‐diazoester groups smoothly through an intramolecular addition/rearrangement process, producing the β‐ketoesters in high yield and enantiomeric excess. 相似文献