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1.
Palladium‐Catalyzed Oxidative Cycloisomerization of 2‐Cinnamyl‐1,3‐Dicarbonyls: Synthesis of Functionalized 2‐Benzyl Furans 下载免费PDF全文
Rajender Nallagonda Reddy Rajasekhar Reddy Dr. Prasanta Ghorai 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(42):14732-14736
A new palladium‐catalyzed intramolecular oxidative cycloisomerization of readily available starting materials, 2‐cinnamyl‐1,3‐dicarbonyls, has been demonstrated for the creation of structurally diverse 2‐benzyl furans. The cycloisomerization occurs by a regioselective 5‐exo‐trig pathway. The reaction shows a broad substrate scope with good to excellent yields. Furthermore, a one‐pot procedure has been executed by using readily available cinnamyl alcohols and 1,3‐diketones. 相似文献
2.
Z‐Selective Hydrothiolation of Racemic 1,3‐Disubstituted Allenes: An Atom‐Economic Rhodium‐Catalyzed Dynamic Kinetic Resolution 下载免费PDF全文
Adrian B. Pritzius Prof. Dr. Bernhard Breit 《Angewandte Chemie (International ed. in English)》2015,54(52):15818-15822
A Z‐selective rhodium‐catalyzed hydrothiolation of 1,3‐disubstituted allenes and subsequent oxidation towards the corresponding allylic sulfones is described. Using the bidentate 1,4‐bis(diphenylphosphino)butane (dppb) ligand, Z/E‐selectivities up to >99:1 were obtained. The highly atom‐economic desymmetrization reaction tolerates functionalized aromatic and aliphatic thiols. Additionally, a variety of symmetric internal allenes, as well as unsymmetrically disubstituted substrates were well tolerated, thus resulting in high regioselectivities. Starting from chiral but racemic 1,3‐disubstituted allenes a dynamic kinetic resolution (DKR) could be achieved by applying (S,S)‐Me‐DuPhos as the chiral ligand. The desired Z‐allylic sulfones were obtained in high yields and enantioselectivities up to 96 % ee. 相似文献
3.
Haydar Kilic Omer Aydin Sinan Bayindir Nurullah Saracoglu 《Journal of heterocyclic chemistry》2016,53(6):2096-2101
Bismuth nitrate catalyzed condensation reactions of indoline with 1,2‐ and 1,3‐diketones were investigated and were reported to proceed via different reaction pathways with the involvement of one or two of the carbonyl groups. While the reaction of indoline with cyclohexane‐1,3‐dione ( 4 ) gave solely condensation product, the reaction between the acetylacetone ( 5 ) and indoline provided N‐acetyl indoline as single products on retro‐aldol process. In contrast to 1,3‐diketones, the reaction with benzil ( 17 ) was performed under difficult conditions and proceeded to give secondary products. 相似文献
4.
《Journal of heterocyclic chemistry》2018,55(1):226-239
Knoevenagel condensation of 5,6‐dihydro‐4H‐pyrrolo[3,2,1‐ij]quinoline‐1,2‐dione 3 with aryl cyanomethyl ketones 9 generates 3‐(aroyl(cyano)methylidene)oxindoles 10 that react with cyclic 1,3‐diketones 11 to generate polycyclic hemiacetal spiro[4H‐2,3‐dihydropyran‐3,3′‐oxindoles] 13 . 相似文献
5.
《中国化学》2018,36(10):929-933
A new palladium‐catalyzed selective aminomethylation of conjugated 1,3‐dienes with aminals via double C—N bond activation is described. This simple method provides an effective and rapid approach for the synthesis of linear α,β‐unsaturated allylic amines with perfect regioselectivity. Mechanistic studies disclosed that one palladium catalyst cleaved two distinct C—N bond to furnish a cascade double C—N bond activation, in which an allylic 1,3‐diamine and allylic 1,2‐diamine were initially formed as key intermediates through the palladium‐catalyzed C—N bond activation of aminal and the α,β‐unsaturated allylic amine was subsequently produced via palladium‐catalyzed C—N bond activation of the allylic diamines. 相似文献
6.
《中国化学》2017,35(10):1595-1600
A facile synthesis of benzo[h ]quinolines has been developed via improved Combes reaction. A combination of silica gel, p ‐toluenesulfonic acid and phosphorus pentoxide was utilized to promote the condensation of 1‐naphthylamines with 1,3‐diketones under solvent free conditions. In this case, silica gel was used as reaction media, p ‐toluenesulfonic acid and phosphorus pentoxide were acted as catalyst and dehydrating agent, respectively. 相似文献
7.
Various fluorinated 3‐oxo ester/1,3‐diketones were reacted with carbonyl compounds, in presence of piperidine and under microwave irradiation, to afford (E)‐α,β‐unsaturated esters and ketones in good yields. The systematic study reveals that the reaction proceeded through the formation of aldol adduct. The method provides a new and simple way for C,C bond formations. 相似文献
8.
Synthesis and Antimicrobial Activity of Racemic 1,5‐Diols: 2‐(1,3‐Diaryl‐3‐hydroxypropyl)cyclohexan‐1‐ol Derivatives 下载免费PDF全文
A series of novel racemic 2‐(1,3‐diaryl‐3‐hydroxypropyl)cyclohexan‐1‐ol derivatives were synthesized from 1,5‐diketones. All the synthesized compounds were characterized by spectroscopic methods. The antibacterial activities of obtained chiral 1,5‐diols were investigated against four Gram‐positive and three Gram‐negative bacteria by determining of minimum inhibitory concentrations (MICs) in vitro. Compounds 3b , 3c , and 3d were found to be active against Enterococcus faecalis and Escherichia coli. In addition, compound 3j were found to be moderately active against all tested bacterial strains. 相似文献
9.
《Journal of heterocyclic chemistry》2018,55(6):1324-1330
Several new derivatives of 9‐aroyl‐3,4,5,6,7,9‐hexahydro‐1H‐xanthene‐1,8(2H)‐dione have been synthesized in yields varying from high to excellent by the condensation reaction of arylglyoxals with 1,3‐diketones (cyclohexane‐1,3‐dione or dimedone) and TPAB as an inexpensive, recoverable, and non‐toxic catalyst in the presence of ethanol/water under reflux conditions. 相似文献
10.
Copper‐Catalyzed γ‐Selective and Stereospecific Allylic Cross‐Coupling with Secondary Alkylboranes 下载免费PDF全文
Yuto Yasuda Kazunori Nagao Yoshinori Shido Prof. Dr. Seiji Mori Prof. Dr. Hirohisa Ohmiya Prof. Dr. Masaya Sawamura 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(27):9666-9670
The scope of the copper‐catalyzed coupling reactions between organoboron compounds and allylic phosphates is expanded significantly by employing triphenylphosphine as a ligand for copper, allowing the use of secondary alkylboron compounds. The reaction proceeds with complete γ‐E‐selectivity and preferential 1,3‐syn stereoselectivity. The reaction of γ‐silicon‐substituted allylic phosphates affords enantioenriched α‐stereogenic allylsilanes. 相似文献
11.
An efficient and mild methodology for the oxidation of primary and secondary alcohols to the corresponding carbonyl functions is described with N,N,N′,N′‐tetrabromobenzene‐1,3‐disulfonamide and poly(N‐bromobenzene‐1,3‐disulfonamide) using microwave irradiation under solvent‐free conditions. Aliphatic, benzylic and allylic alcohols are rapidly oxidized without over‐oxidation to carboxylic acids. Secondary carbinols are slowly oxidized so that the reaction is highly chemoselective. 相似文献
12.
Dr. Paramita Mukherjee Prof. Ross A. Widenhoefer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(10):3437-3444
A 1:1 mixture of [AuCl(IPr)] (IPr=1,3‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidine) and AgClO4 catalyzes the intermolecular dehydrative alkoxylation of primary and secondary allylic alcohols with aliphatic primary and secondary alcohols to form allylic ethers. These transformations are regio‐ and stereospecific with preferential addition of the alcohol nucleophile at the γ‐position of the allylic alcohol syn to the departing hydroxyl group and with predominant formation of the E stereoisomer. The minor α regioisomer is formed predominantly through a secondary reaction manifold involving regioselective γ‐alkoxylation of the initially formed allylic ether rather than by the direct α‐alkoxylation of the allylic alcohol. 相似文献
13.
Majid M. Heravi Samaheh Sadjadi Hossein A. Oskooie Rahim Hekmatshoar Fatemeh F. Bamoharram 《中国化学会会志》2008,55(4):842-845
3H‐1,5‐benzodiazepines were synthesized by the condensation of o‐phenylendiamine and various 1,3‐diketones in the presence of various heteropolyacid (HPA) catalysts under mild conditions in very good yields and with high selectivity. 相似文献
14.
Cong‐Rong Liu Man‐Bo Li Cui‐Feng Yang Shi‐Kai Tian Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(3):793-797
The acid‐catalyzed benzylic and allylic alkylation of protic nucleophiles is fundamentally important for the formation of carbon? carbon and carbon? heteroatom bonds, and it is a formidable challenge for benzylic and allylic amine derivatives to be used as the alkylating agents. Herein we report a highly efficient benzylic and allylic alkylation of protic carbon and sulfur nucleophiles with sulfonamides through double Lewis acid catalyzed cleavage of sp3 carbon–nitrogen bonds at room temperature. In the presence of a catalytic amount of inexpensive ZnCl2‐TMSCl (TMSCl: chlorotrimethylsilane), 1,3‐diketones, β‐keto esters, β‐keto amides, malononitrile, aromatic compounds, thiols, and thioacetic acid can couple with a broad range of tosyl‐activated benzylic and allylic amines to give diversely functionalized products in good to excellent yields and with high regioselectivity. Furthermore, the cross‐coupling reaction of 1,3‐dicarbonyl compounds with benzylic propargylic amine derivatives has been successfully applied to the one‐step synthesis of polysubstituted furans and benzofurans. 相似文献
15.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(39):12037-12041
Reported herein is a light‐triggered organocatalytic strategy for the desymmetrization of achiral 2‐fluoro‐substituted cyclopentane‐1,3‐diketones. The chemistry is based on an intermolecular aldol reaction of photochemically generated hydroxy‐o ‐quinodimethanes and simultaneously forges two adjacent fully substituted carbon stereocenters, with one bearing a stereogenic carbon–fluorine unit. The method uses readily available substrates, a simple chiral organocatalyst, and mild reaction conditions to afford an array of highly functionalized chiral 2‐fluoro‐3‐hydroxycyclopentanones. 相似文献
16.
The reaction of the enolizable thioketone (1R,4R)‐thiocamphor (= (1R,4R)‐1,7,7‐trimethylbicyclo[2.2.1]heptane‐2‐thione; 1 ) with (R)‐2‐vinyloxirane ( 2 ) in the presence of a Lewis acid such as SnCl4 or SiO2 in anhydrous CH2Cl2 gave the spirocyclic 1,3‐oxathiolane 3 with the vinyl group at C(4′), as well as the isomeric enesulfanyl alcohol 4 . In the case of SnCl4, an allylic alcohol 5 was obtained in low yield in addition to 3 and 4 (Scheme 2). Repetition of the reaction in the presence of ZnCl2 yielded two diastereoisomeric 4‐vinyl‐1,3‐oxathiolanes 3 and 7 together with an alcohol 4 , and a ‘1 : 2 adduct’ 8 (Scheme 3). The reaction of 1 and 2 in the presence of NaH afforded regioselectively two enesulfanyl alcohols 4 and 9 , which, in CDCl3, cyclized smoothly to give the corresponding spirocyclic 1,3‐oxathiolanes 3, 10 , and 11 , respectively (Scheme 4). In the presence of HCl, epimerization of 3 and 10 occurred to yield the corresponding epimers 7 and 11 , respectively (Scheme 5). The thio‐Claisen rearrangement of 4 in boiling mesitylene led to the allylic alcohol 12 , and the analogous [3,3]‐sigmatropic rearrangement of the intermediate xanthate 13 , which was formed by treatment of the allylic alcohol 9 with CS2 and MeI under basic conditions, occurred already at room temperature to give the dithiocarbonate 14 (Schemes 6 and 7). The presented results show that the Lewis acid‐catalyzed as well as the NaH‐induced addition of (R)‐vinyloxirane ( 2 ) to the enolizable thiocamphor ( 1 ) proceeds stereoselectively via an SN2‐type mechanism, but with different regioselectivity. 相似文献
17.
The development of efficient methods for stereocontrolled synthesis of polyol derivatives has been of continuing interest for the synthetic community. We describe herein tandem olefin cross‐metathesis/hemiacetalization/intramolecular oxa‐Michael addition of allylic/homoallylic alcohols, α,β‐unsaturated ketones, and aldehydes, which enabled the synthesis of syn‐1,2‐ and syn‐1,3‐diol derivatives in a step‐economical manner. A series of differentially protected polyol derivatives could be obtained in subsequent transformations via chemoselective/regioselective cleavage of the acetal moiety of the tandem reaction products. 相似文献
18.
《Journal of heterocyclic chemistry》2017,54(1):753-757
One‐pot reaction of cyclic 1,3‐diketones, dimethylformamide dimethylacetal (DMFDMA) and 2‐(1H‐benzo[d ]imidaz‐2‐yl)acetonitrile was found to be a highly selective process leading to 4‐oxo‐1,2,3,4‐tetrahydrobenzo[4,5]imidazo[1,2‐a ]quinolin‐6‐yl cyanides. Optimized reaction conditions using water as solvent at room temperature or under microwave heating allowed high yields of the target products required no additional purification. 相似文献
19.
Ming Joo Koh R. Kashif M. Khan Sebastian Torker Amir H. Hoveyda 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(7):1999-2003
A broadly applicable Ru‐catalyzed protocol for Z‐selective ring‐opening/cross‐metathesis (ROCM) is disclosed. In addition to reactions relating to terminal alkenes of different sizes, the first examples of Z‐selective ROCM processes involving heteroaryl olefins, 1,3‐dienes, and O‐ and S‐substituted alkenes as well as allylic and homoallylic alcohols are reported. Z‐Selective transformations with an α‐substituted allylic alcohol are shown to afford congested Z alkenes with high diastereoselectivity. Transformations are performed in the presence of 2.0–5.0 mol % of a recently disclosed Ru‐based dithiolate complex that can be easily prepared in a single step from commercially available starting materials. Typically, transformations proceed at ambient temperature and are complete within eight hours; products are obtained in up to 97 % yield, >98:2 Z/E, and >98:2 diastereomeric ratio. The present investigations reveal a mechanistically significant attribute of the Ru‐based dithiolates that arises from electrostatic interactions with anionic S‐based ligands. 相似文献
20.
Synthesis of Cyclobutenes and Allenes by Cobalt‐Catalyzed Cross‐Dimerization of Simple Alkenes with 1,3‐Enynes 下载免费PDF全文
Akira Nishimura Eri Tamai Dr. Masato Ohashi Prof. Dr. Sensuke Ogoshi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(22):6613-6617
Cobalt‐catalyzed cross‐dimerization of simple alkenes with 1,3‐enynes is reported. A [2+2] cycloaddition reaction occurred, with alkenes bearing no allylic hydrogen, by reductive elimination of a η3‐butadienyl cobaltacycle. On the other hand, aliphatic alkenes underwent 1,4‐hydroallylation by means of exo‐cyclic β‐H elimination. These reactions can provide cyclobutenes and allenes that were previously difficult to access, from simple substrates in a highly chemo‐ and regioselective manner. 相似文献