共查询到20条相似文献,搜索用时 15 毫秒
1.
Karandeep Singh Bhanwar Kumar Malviya Ved Prakash Verma Satpal Singh Badsara Vimal K. Bhardwaj Siddharth Sharma 《Tetrahedron》2019,75(17):2506-2520
A divergent regioselective palladium (II) catalyzed approach through post Ugi cyclization is described. The Ugi adduct underwent intramolecular ortho-hydroarylation via 6-endo-dig cyclization for the direct access to 4-aryl-2-quinolones. Incorporation of iodine at the C-3 position of 2-quinolone followed by Suzuki-Miyaura coupling results into the more diversified 3,4-diaryl-2-quinolones. 相似文献
2.
A catalyst-free intramolecular formal Heck reaction has been developed, affording 9-benzylidene-9H-fluorene derivatives under UV irradiation. This reaction probably proceeds via UV-induced homolytic cleavage of CI bond, addition of the aryl radical to the alkene moiety, single electron oxidation of alkyl radical intermediate into carbocation species, and deprotonation. 相似文献
3.
Alkenes are desirable and highly versatile starting materials for organic transformations, and well-known substrates for palladium catalysis. Typically, these reactions result in the formation of a new alkene product via β-hydride elimination. In contrast to this scenario, our laboratory has been involved in the development of alkene hydro- and difunctionalization reactions, where β-hydride elimination can be controlled. We report herein the development of an asymmetric palladium-catalyzed hydroarylation, which yields diarylmethine products in up to 75% ee. Interestingly, a linear free energy relationship is observed between the steric bulk of the ligand within a certain range and the ee of the reaction. 相似文献
4.
Takuya Hashimoto 《Tetrahedron letters》2010,51(4):761-8145
FeCl3/AgOTf-catalyzed hydroarylation of propiolic acid with electron-rich arenes such as mesitylene, tetramethylbenzene, and pentamethylbenzene in trifluoroacetic acid proceeded to give 3-arylpropenoic acids in moderate to high yields. The same reactions with anisole and 1,4-dimethoxybenzene afforded double hydroarylation products, 3,3-diarylpropionic acids. 相似文献
5.
We have designed and synthesized several basic and novel fused ring heterocycles by intramolecular hydroarylation with an efficiency and scope to develop intermediates of potential value. This method demonstrated consistent performance with arene-ene and arene-yne substrates of diverse structural features, including propargyl ethers, allyl thioethers, and propargyl thioethers resulting in 6-endo products. 相似文献
6.
An iron-catalyzed intramolecular alkyne-aldehyde metathesis strategy of the alkynyl ether of salicylaldehyde derivatives has been developed which works under mild reaction conditions to produce the functionalized 2H-chromene derivatives. This protocol is compatible toward a wide range of functional groups, such as methoxy, fluoro, chloro, bromo, and phenyl groups. This method provides an atom-economical and environmentally friendly approach for the synthesis of a series of substituted 2H-chromenes. 相似文献
7.
A one-pot synthesis of novel poly-substituted phenanthrenes is described in this article through a Suzuki-Miyaura cross-coupling followed by a Dieckmann-Thorpe ring closure under microwave irradiation. The selection of the appropriate starting materials allowed us to introduce diversity on various positions of the phenanthrene ring system. 相似文献
8.
Xavier Bantreil Nasreddine Kanfar Nicolas GehinEthan Golliard Pauline OhlmannJean Martinez Frédéric Lamaty 《Tetrahedron》2014
A convenient and user-friendly method to yield benzamides from primary and secondary amines and various benzylic alcohols in the presence of a cheap iron salt (FeCl2·4H2O) and tert-butylhydroperoxide (70% in water) as a stoichiometric oxidant is described. Control experiments indicated that this reaction might involve radical species. This method proved to be general, generating a family of 30 benzamides and was applied to the preparative synthesis of anti-anxiety drug moclobemide. 相似文献
9.
Xin Wang Mengpei Bai Meiqi Pei Xinrui Xu Die Wu Siyang Xing Kui Wang Bolin Zhu Hanyu Xia 《Tetrahedron letters》2019,60(42):151151
An unexpected cyclization reaction of N-sulfonyl 1,2,3-triazoles carrying the electron-deficient alkenes with amines under the catalysis of Lewis acid has been accomplished. This strategy involves the removal of the sulfonyl group and further intramolecular 1,4-addition, providing a series of 1,2,3-triazole-fused isoindoline compounds in good yields under the mild conditions. 相似文献
10.
Christopher C. McAtee Duncan C. Ellinwood Rory C. McAtee Corinna S. Schindler 《Tetrahedron》2018,74(26):3306-3313
We report herein the intramolecular α-tert-alkylation of unsaturated β-ketoesters which gives rise to highly functionalized cyclopentanes. This transformation is characterized by its operational simplicity, mild reaction conditions and the use of scandium (III) triflate as a Lewis acid catalyst. Of interest, cyclopentanes bearing heterocycles, sites for post reaction functionalization and spirocyclic architectures are accessible with this strategy. 相似文献
11.
Pablo Bernal 《Tetrahedron letters》2006,47(17):2905-2909
A new methodology has been developed for the preparation of β-alkoxy and β-sulfenyl ketones by hetero-Michael addition of the corresponding alcohols and thiols to enones under acidic and basic conditions. The direct conversion of enones into β-alkoxy and β-sulfenyl α-oximinoketones was also described. 相似文献
12.
Takuya Hashimoto 《Journal of organometallic chemistry》2011,696(1):99-105
Hydroarylation of propiolic acids with various arenes in TFA proceeded efficiently in the presence of FeCl3/AgOTf catalyst system. In the case of electron-rich arenes, the iron-catalyzed hydroarylation gave cinnamic acids in moderate to high yields. The hydroarylation of phenylacetylene was observed but the catalyst was not effective under the same conditions. 相似文献
13.
《Tetrahedron letters》2014,55(52):7190-7193
An iron-catalyzed coupling reaction of methylarenes with thiols leading to thioesters has been developed. The reactions were carried out in water with tert-butyl hydroperoxide (TBHP) as the oxidant and polyoxyethanyl α-tocopheryl sebacate (PTS) as the surfactant. The reaction medium is compatible with a series of functional groups and can be reused. 相似文献
14.
《Tetrahedron letters》2004,45(11):2377-2380
The β-substituted captodative olefins methyl 2-aryloxy-3-dimethylaminopropenoates 4a-h were synthesized, via aminomethylenation of the corresponding 2-phenoxyacetic esters 9a-h. Lewis acid promoted intramolecular cyclization of alkenes 4 led to benzofurans 7a-h, in an efficient synthetic approach to the benzofuran frame. 相似文献
15.
Igor Dias Jurberg 《Journal of organometallic chemistry》2011,696(1):37-5148
A study concerning the gold(I)-catalyzed hydroarylation of N-propargyl-N′-arylhydrazinecarboxylic acid methyl esters is described. The use of the gold complex [XPhosAu(NCCH3)SbF6] as the catalyst in refluxing nitromethane allows the generally rapid and efficient synthesis of a range of functionalized 4-exo-methylene-1,2-dihydrocinnolines. 相似文献
16.
A direct DDQ-mediated dehydrogenative intramolecular cyclization of (Z)-1,2,3-triaryl substituted propylenes promoted by Cu(OAc)2 was developed, providing 1,2-diarylindene derivatives in moderate to good yields (up to 92%) under mild conditions. This protocol provides a straightforward access to 1,2-diarylindenes via DDQ-mediated benzylic/allylic sp3 C–H bond activation. 相似文献
17.
Zhen-Zhen Gu Feng-Chao Guo Pu Zhang Yu-Jun Qin Zhi-Xin Guo 《Tetrahedron letters》2019,60(26):1687-1690
Acetophenones with a variety of substituents could be converted to diacylfuroxans in a solvent-free reaction by combining the reagents Fe(NO3)3·9H2O and P2O5 under high-speed ball milling. This reaction was facile and eco-friendly, and exhibits advantages in terms of better toleration, safety, and easier operation. The nitrate acid and nitrogen dioxide generated in situ should play a major role in this mechanochemical reaction. 相似文献
18.
19.
María del Carmen Cruz 《Tetrahedron》2005,61(42):10061-10072
The intramolecular cyclization of the β-substituted olefins methyl 2-aryloxy-3-dimethylaminopropenoates 3a-3f catalyzed by Lewis acids leads to a short and novel synthesis of benzofurans 2a-2f. When the olefins 4-dimethylamino-3-aryloxy-3-buten-2-ones 4a-4f were used, the cyclization process was faster and provided the corresponding substituted 2-acetylbenzofurans 1a-1f. Among the latter, naturally occurring compounds calebertin (1a), caleprunin A (1b), and caleprunin B (1c) were prepared in good overall yields. These benzofurans were also obtained by direct treatment under MW irradiation of the precursors 1-aryloxypropan-2-ones 7a-7c with DMFDMA, followed by addition of the catalyst, resulting in a route that was one step shorter. 相似文献
20.
Naoko Saino 《Journal of organometallic chemistry》2006,691(14):3129-3136
An iron species derived from FeCl2 or FeCl3 by in situ reduction with zinc powder in the presence of imidazol-2-ylidene or bidentate nitrogen ligand could effectively catalyze intramolecular cycloisomerization of triynes to annulated benzenes. With a 2-iminomethylpyridine ligand, hydrates of FeCl2 and FeCl3 as well as their anhydrous ones could be used. 相似文献