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1.
[reaction: see text] Allyl tosylate is a good allyl source for a novel palladium-catalyzed benzannulation that affords polysubstituted benzenes from 1 mol of an allyl compound and 2 mol of internal alkynes. Using triphenyl phosphite as a ligand, the reaction with terminal alkynes gave trisubstituted benzenes regioselectively. 相似文献
2.
Gevorgyan V Radhakrishnan U Takeda A Rubina M Rubin M Yamamoto Y 《The Journal of organic chemistry》2001,66(8):2835-2841
A new concept of highly chemo- and regioselective formation of the benzene ring by a palladium-catalyzed formal [2 + 2 + 2] sequential intermolecular trimerization of alkynes is proposed. Homodimerization of terminal alkynes and subsequent [4 + 2] benzannulation with diynes gives tetrasubstituted benzenes in moderate to good yields. The introduction of two different alkynes (terminal and internal) in the first step of the sequence allows for construction of pentasubstituted benzenes from three different acyclic acetylenic units. In all cases the tetra- and pentasubstituted benzenes are formed as a single reaction product without being accompanied by any of regio- or chemoisomers. A significant acceleration of the sequential trimerization reaction in the presence of Lewis acid/phosphine combined system was observed. Mechanistic studies reveal that the Lewis acid assisted isomerization of the E-enyne formed in the first step of the sequence to the more reactive Z-isomer is responsible for the observed acceleration effect. The proposed methodology provides a conceptually new and synthetically useful route to multifunctional aromatic compounds. 相似文献
3.
Zn-catalyzed [4 + 2] benzannulation of 2-ethynylbenzaldehydes with alkynes is described for the selective synthesis of naphthalene derivatives. In the presence of ZnCl2, a variety of 2-ethynylbenzaldehydes underwent the [4 + 2] benzannulation reactions with alkynes to selectively afford the corresponding naphthalene derivatives in moderate to good yields. 相似文献
4.
The synthesis of 1,6-dihydropyrrolo[2,3-g]indazole derivatives is described. The indolic ring system is constructed via a Larock palladium-catalyzed annulation using terminal and internal alkynes. Additionally, when using internal alkynes for this reaction, we found that a directing effect on regioselectivity was mediated by the ester group of alkyl 3-substituted propiolate derivatives. 相似文献
5.
Highly functionalized benzenes were precisely synthesized via multi-step processes consisting of ruthenium-catalyzed [2+2+2] cycloaddition of diiododiynes with an ethynylboronate or terminal alkynes, and subsequent chemo- and regio-selective palladium-catalyzed C-C bond-forming reactions of the resulting cycloadducts. The sequential cycloaddition/coupling process was applied to the synthesis of oligo(p-phenylene ethynylene)s. 相似文献
6.
Catalin Vasile Maftei Martin Heiko Franz Christian Kleeberg Ion Neda 《Molecules (Basel, Switzerland)》2021,26(11)
The substance class of the well-known Cinchona alkaloids is widened by 6′-Amino-cinchonine and 6′-Amino-cinchonidine, novel compounds which incorporate a primary amino function in the quinolinic ring system. These key intermediates open the field for a range of fruitful chemistry. Here is described a short and direct pathway for the synthesis of triazole containing derivatives of the above-mentioned substances using the [3 + 2] Huisgen cycloaddition. For this purpose, the amines were first converted into the corresponding azides. Based on this, non-substituted and silyl-protected triazoles were synthesized as examples. Furthermore, didehydrated derivatives of quincorine and quincoridine were used as addition partners, resulting in compounds that carry the quinuclidine ring of the cinchona alkaloids at both ends. Some of these compounds were examined radiographically to investigate the position of the quinuclidine ring to the triazole. The solid-state structures of compounds 10, 11 and 28 were determined by X-ray diffraction analyses. 相似文献
7.
Bei Wu 《Tetrahedron letters》2010,51(49):6433-6435
3,4,7,8-Tetrahydro-2H-chromene-2,5(6H)-dione derivatives were efficiently synthesized with excellent selectivity via a [3+2+1] cyclocarbonylative coupling of 1,3-cyclohexanediones, terminal alkynes, and CO catalyzed by Pd(PPh3)4. 相似文献
8.
Shashikant U. Dighe Surya K. Samanta Shivalinga Kolle Sanjay Batra 《Tetrahedron》2017,73(17):2455-2467
An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y1 and Y2. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones. 相似文献
9.
Dmitry V Kadnikov 《Journal of organometallic chemistry》2003,687(2):425-435
o-Iodophenols and o-iodoaniline derivatives react with terminal alkynes under 1 atm of CO in the presence of pyridine and catalytic amounts of Pd(OAc)2 to generate coumarins and 2-quinolones, respectively, as the only products. Terminal alkynes bearing alkyl, aryl, silyl, hydroxyl, ester and cyano substituents are effective in these processes affording the desired products in moderate yields. The formation of coumarins and 2-quinolones in this process is in stark contrast with all previously described palladium-catalyzed reactions of o-iodophenols or o-iodoanilines with terminal alkynes and CO, which have afforded chromones and 4-quinolones. Moreover, under our reaction conditions terminal alkynes insert into the carbonpalladium bond instead of undergoing a Sonogashira-type coupling as confirmed by an isotope labeling experiment. 相似文献
10.
A. B. Lipeeva E. E. Shul’ts M. M. Shakirov G. A. Tolstikov 《Russian Journal of Organic Chemistry》2013,49(1):99-107
The reaction of a linearly fused furocoumarin, oreoselone, with p-toluenesulfonyl chloride gave 2-tosyloreoselone which showed a high reactivity in palladium-catalyzed cross-coupling reactions with formation of a new carbon-carbon bond. 2-Tosyloreoselone reacted with terminal alkynes in the presence of Pd(PPh3)2Cl2 to give the corresponding 2-alkynylfuro[3,2-g]chromen-3-ones. 2-Aryl(hetaryl)alkynyloreoselones were obtained in high yield directly by palladium-catalyzed reaction of oreoselone with tosyl chloride and aryl(hetaryl)acetylenes. The reaction of 2-tosyloreoselone with aryl(hetaryl)boronic acids in the presence of palladium complexes with uni- and bidentate ligands, tetrabutylammonium bromide, and a base afforded 2-aryl(hetaryl)-substituted oreoselones. 2-Vinyloreoselone was synthesized from 2-tosyloreoselone and potassium trifluoro(vinyl)borate. 相似文献
11.
Dr. Wei Wei Ka Key Cheung Dr. Ran Lin Lam Cheung Kong Ka Lok Chan Dr. Herman H. Y. Sung Prof. Dr. Ian D. Williams Prof. Dr. Rongbiao Tong Prof. Dr. Zhenyang Lin Prof. Dr. Guochen Jia 《Angewandte Chemie (International ed. in English)》2023,62(36):e202307251
A unique benzannulation strategy for regioselective de novo synthesis of densely functionalized phenols is described. Through metal-mediated formal [2+2+1+1] cycloaddition of two different alkynes and two molecules of CO, a series of densely functionalized phenols were obtained. The benzannulation strategy allows efficient regioselective installation up to five different substituents on a phenol ring. The resulting phenols have a substitution pattern different from those obtained from Dötz and Danheiser benzannulations. 相似文献
12.
The RhCl3·3H2O/i-Pr2NEt-catalyzed [2+2+2] cyclotrimerization of alkynes has been achieved. The reaction can be widely used for various alkynes and provides tri- or hexa-substituted benzenes regioselectively in high yields. The [2+2+2] cycloaddition of diynes and alkynes is also developed, and it affords benzene derivatives in moderate to high yields. 相似文献
13.
Hexafluoroantimonic Acid Catalysis: Formal [3+2+2] Cycloaddition of Aziridines with Two Alkynes
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Ming‐Bo Zhou Ren‐Jie Song Prof. Dr. Jin‐Heng Li 《Angewandte Chemie (International ed. in English)》2014,53(16):4196-4199
A practical method for the synthesis of azepine derivatives, a typical seven‐membered heterocyclic ring system, was developed and involves the use of hexafluoroantimonic acid to catalyze a formal [3+2+2] cycloaddition of aziridines with two alkynes. This method was applicable to two of the same or different terminal alkynes for the [3+2+2] cycloaddition with unactivated aziridines, and furnished the corresponding azepine derivatives in good yields with good levels of chemo‐ and regioselectivity. The mechanism was also discussed according to the results of the in situ HRMS and 1H NMR analysis. 相似文献
14.
Prof. Dr. Yoshihiko Yamamoto Jiyue Jiang Dr. Takeshi Yasui 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(17):3749-3757
The palladium-catalyzed reaction of 4-iodo-2-quinolones with activated alkynes was investigated. Cyclopenta[de]quinoline-2(1 H)-ones and/or phenanthridine-6(5 H)-ones were obtained through [3+2] annulation involving aromatic C−H activation or [2+2+2] annulation involving vinylic C−H activation, respectively. Reasonable mechanisms for the formation of these annulation products have been proposed based on density functional theory calculations. 相似文献
15.
《Tetrahedron: Asymmetry》2001,12(14):1983-1985
New β-aminoalkylphosphines with a stereogenic nitrogen center have been synthesized from quincorine and quincoridine. Nickel catalysts were studied for their enantioselectivity in the asymmetric Kumada–Corriu reaction. The (2S,4S,5R)-2-diphenylphosphinomethyl-5-ethyl-quinuclidine–nickel complex led to e.e. of 85% for the cross-coupling of 1-phenylethylmagnesium chloride with vinyl bromide. 相似文献
16.
Rhodium‐Catalyzed [3+2+2] and [2+2+2] Cycloadditions of Two Alkynes with Cyclopropylideneacetamides
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Tomoka Yoshida Yuki Tajima Masayuki Kobayashi Koji Masutomi Prof. Dr. Keiichi Noguchi Prof. Dr. Ken Tanaka 《Angewandte Chemie (International ed. in English)》2015,54(28):8241-8244
It has been established that a cationic rhodium(I)/H8‐binap complex catalyzes the [3+2+2] cycloaddition of 1,6‐diynes with cyclopropylideneacetamides to produce cycloheptadiene derivatives through cleavage of cyclopropane rings. In contrast, a cationic rhodium(I)/(S)‐binap complex catalyzes the enantioselective [2+2+2] cycloaddition of terminal alkynes, acetylenedicarboxylates, and cyclopropylideneacetamides to produce spiro‐cyclohexadiene derivatives which retain the cyclopropane rings. 相似文献
17.
The reaction of o-alkynyl(oxo)benzenes 1 with alkynes 2 in the presence of a catalytic amount of AuCl(3) in (CH(2)Cl)(2) at 80 degrees C gave the [4+2] benzannulation products, naphthyl ketone derivatives 3 and 4, in high yields. When the reaction was carried out using AuBr(3) instead of AuCl(3), the reaction speed was enhanced and the chemical yield was increased. On the other hand, when the reaction was carried out in the presence of a catalytic amount of Cu(OTf)(2) and 1 equiv of a Br?nsted acid, such as CF(2)HCO(2)H, in (CH(2)Cl)(2) at 100 degrees C, the decarbonylated naphthalene products 5 were obtained in high yields. Similarly, the Cu(OTf)(2)-H(2)O-promoted reaction of the enynals 7 with an alkyne 2 afforded the corresponding [4+2] benzannulation products, decarbonylated benzene derivatives 8, in good yields. Both AuX(3)- and Cu(OTf)(2)-catalyzed benzannulations proceed most probably through the formation of the benzo[c]pyrylium ate complex 10, the Diels-Alder addition of alkynes 2 to the ate complex, and the resulting bicyclic pyrylium ion intermediate 12. The mechanistic difference between the AuX(3) and Cu(OTf)(2)-HA system is discussed. 相似文献
18.
Gilson Zeni Cristina W. NogueiraDagoberto O. Silva Paulo H. MenezesAntonio L. Braga Hélio A. StefaniJoão B.T. Rocha 《Tetrahedron letters》2003,44(4):685-688
Both symmetrically and unsymmetrically substituted 2,5-bis-(acetylenic) thiophene derivatives were obtained in good yields under mild conditions through palladium-catalyzed cross coupling reaction of 2,5-bis-(butyltelluro) thiophene 2 and terminal alkynes. The methodology represents a general and efficient protocol for carrying out the synthesis of thiophene derivatives with potential biological activities. 相似文献
19.
Sirisilla Raju Venkateswara Rao Batchu R. Vasu Dev J. Moses Babu P. Rajender Kumar Pazhanimuthu Annamalai 《Tetrahedron》2006,62(41):9554-9570
We herein report a highly convenient protocol for rapid construction of α-pyrone fused with thiophene. This includes one-pot and regioselective synthesis of 4,5-disubstituted and 5-substituted thieno[2,3-c]pyran-7-ones, 6,7-disubstituted and 6-substituted thieno[3,2-c]pyran-4-ones. The synthesis of thieno[2,3-c]pyran-7-ones involves palladium mediated cross coupling of 3-iodothiophene-2-carboxylic acid with terminal alkynes in a simple synthetic operation. The coupling-cyclization reaction was initially studied in the presence of Pd(PPh3)2Cl2 and CuI in a variety of solvents. 5-Substituted 4-alkynylthieno[2,3-c]pyran-7-ones were isolated in good yields when the reaction was performed in DMF. Similarly, 6-substituted 7-alkynylthieno[3,2-c]pyran-4-ones were synthesized via palladium-catalyzed cross coupling of 2-bromothiophene-3-carboxylic acid with terminal alkynes. A tandem C-C bond forming reaction in the presence of palladium catalyst rationalizes the formation of coupled product in this apparently three-component reaction. The cyclization step of this coupling-cyclization-coupling process occurs in a regioselective fashion to furnish products containing six-membered ring only. This sequential C-C bond forming reaction however, can be restricted to the formation of single C-C bond by using 10% Pd/C-Et3N-CuI-PPh3 as catalyst system in the cross coupling reaction. 5-Substituted thieno[2,3-c]pyran-7-ones were obtained in good yields when the coupling reaction was performed under this condition. Some of the compounds synthesized were tested in vitro for their anticancer activities. 相似文献
20.
We herein report the efficient and convenient synthesis of 6-substituted-5H-pyrrolo[2,3-b]pyrazines. The reaction is a palladium-catalyzed heteroannulation process followed by deprotection to yield the desired pyrrolo[2,3-b]pyrazine substrates. The reaction starts with readily accessible N-(3-chloropyrazin-2-yl)-methanesulfonamide and commercially available terminal alkynes and works with aryl- and alkylalkynes. 相似文献