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1.
The first synthesis of a series of nitro-substituted 2,2-diphenyl-2H-1-benzopyrans is reported. Our synthetic approach is based on a linear synthesis in two steps from appropriate brominated 2,2-diphenyl-2H-1-benzopyrans 12-17, which requires the preliminary preparation of bromophenols 7-11. These latter were easily obtained by the reaction of phenols 1-5 with a mild and selective brominating agent tetrabutylammonium tribromide (TBA·Br3). The key intermediates 12-17 were efficiently elaborated through an univocal classic chromenization between the commercially available 1,1-diphenyl-2-yn-1-ol and the brominated phenols 6-11. The compounds 12-17 so obtained were converted into arylboronic acids 18-23 by a metalation/boronylation sequence, followed by acid hydrolysis. From advanced building blocks 18-23, the introduction of nitro group, which constitutes the ultimate step of our strategy, was achieved by an ipso-nitration reaction using the Crivello's reagent. This highly selective method provides only the ipso-nitrated products 24-29 in moderate to high yield. 相似文献
2.
Olga V. Vinogradova 《Tetrahedron letters》2009,50(46):6358-6941
Cleavage of ortho-(dodeca-1,3-diynyl)triazenes in HCl or HBr medium and subsequent cyclization of the resulting diazonium salts is investigated. In the absence of a strong electron-withdrawing substituent, the reaction affords 3-alkynyl-4-bromo(chloro)cinnolines as the only product. A methoxycarbonyl group promotes hydrolysis of 4-halocinnolines which results in the formation of by-products: furo[3,2-c]cinnoline and cinnolinone. Substitution of bromine in 3-(alk-1-ynyl)-4-bromocinnolines is achieved with methylamine, Na2S and ethynylbenzene affording pyrrolo[3,2-c]cinnoline, thieno[3,2-c]cinnoline and 3,4-diethynylcinnoline, respectively. 相似文献
3.
Three series of S-(1(3H)-isobenzofuranone-3-yl)isothiuronium bromides differing in substitution at the isothiuronium moiety (none, one or two methyl groups) and at the benzene ring were prepared and characterized. These salts were then treated with various bases (acetate, triethylamine, Na2CO3) to give either 1-hydroxy-3-oxo-1,3-dihydro-2H-isoindol-2-carbothioamides or the product of S to N isobenzofuranone-3-yl migration, i.e., 1,3-dimethyl-1-(3-oxo-1,3-dihydro-2-benzofuran-1-yl)thioureas. If ammonia was used in reaction with N,N′-dimethyl isothiuronium salts then 3-hydroxy-2,3-dihydro-1H-isoindol-1-ones were formed together with 1,3-dimethyl-1-(3-oxo-1,3-dihydro-2-benzofuran-1-yl)thioureas in parallel reaction with the yields increasing with ammonia concentration. The formation of isoindolones takes place in two steps with an aldehyde intermediate, which can be trapped with N,N-dimethylhydrazine. 相似文献
4.
Sun Pil Park 《Tetrahedron》2009,65(24):4703-242
A simple method for synthesizing substituted 4H-pyrrolo[1,2-a][1]benzazepines using acid-assisted cyclization of the Morita-Baylis-Hillman adducts of 2-(1H-pyrrol-1-yl)benzaldehydes with methyl acrylate or methyl vinyl ketone as a key step has been developed. 相似文献
5.
Acylation of substituted 4-(furyl-2)-4-arylaminobut-1-enes with maleic anhydride provided 2-allyl-6-carboxy-4-oxo-3-aza-10-oxatricyclo[5.2.1.01,5]dec-8-enes in high yield under mild reaction conditions. The Diels-Alder adducts are formed via an initial amide formation followed by a stereoselective intramolecular [4+2] exo-cycloaddition reaction. Treatment of the tricyclic compounds with phosphoric acid at high temperatures (70-120 °C) promoted cyclic ether opening, intramolecular cyclization and aromatization to give the corresponding tetracyclic compounds, 5,6,6a,11-tetrahydro-10-carboxyisoindolo[2,1-a]quinolines, in moderate yields. The influence of the acid and the reaction temperature on the cyclization reactions are also discussed. 相似文献
6.
Copper-catalyzed tandem reaction of ortho-bromobenzamides and isothiocyanates is described, which provides an efficient and practical route for the synthesis of 2-thioxo-2,3-dihydroquinazolin-4(1H)-ones. The optimal condition involved the following parameters: CuI as precatalyst, Cs2CO3 as base, N,N′-dimethylethane-1,2-diamine as ligand, and toluene as solvent, with reaction temperature at 120 °C. 相似文献
7.
Leonor Y. Vargas Méndez 《Tetrahedron letters》2007,48(14):2509-2512
Efficient synthesis of new 3′,4′-dihydrospiro[piperidine-4,2′(1′H)quinolines] by a four step synthetic route based on 1-benzyl-4-piperidone reactivity is reported. 相似文献
8.
In this study, a novel and convenient route for the construction of 5-((1H-1,2,4-triazol-1-yl)methyl)-1H-indoles (8) is presented starting from (1H-1,2,4-triazol-1-yl)methanol (5) and indolines (6) under 98% H2SO4 at room temperature for 4–24 h, followed by deacetylation and dehydrogenation. Based on this finding, a novel route to synthesize Rizatriptan starting from tryptamine was designed and accomplished with 48.5% overall yield in 6 steps. Compared with operational art, the new route afforded higher yield and more pure products requiring no chromatographic purification, which may further be applied in industrialization. 相似文献
9.
Nazariy T. Pokhodylo 《Tetrahedron》2008,64(7):1430-1434
4,5-Disubstituted and 4-substituted alkyl 2-amino-thiophene-3-carboxylates react with triethyl orthoformate and sodium azide in acetic acid to yield new 2-(1H-tetrazol-1-yl)-4-R1-5-R2-thiophene derivates. It was established that the reaction of these tetrazoles with hydrazine generates the insufficiently studied 2,3-diaminothieno[2,3-d]pyrimidin-4(3H)-one system. It is significant that the reaction mentioned above is the unique tetrazole ring cleavage under the action of hydrazine. 相似文献
10.
The cycloaddition of 2- or 2,3-substituted 1-thia- and 1-thia-3-aza-4-dimethylamino-buta-1,3-dienes with various dienophiles in the presence of a Lewis acid provides a rapid and diastereoselective access to the 3,4-dihydro-2H-thiopyran and 5,6-dihydro-4H-[1,3]thiazine backbones. The generally observed trans relationship between the two newly created strereogenic centres was demonstrated to be the expression of a thermodynamic control of the reaction. The use of chiral dienophile derived from chiral oxazolidin-2-ones allowed us to prepare enantiopure 5,6-dihydro-4H-[1,3]thiazines and 3,4-dihydro-2H-thiopyrans. In the asymmetric synthetic process the chiral auxiliary removal step was best accomplished in the presence of samarium triflate in methanol. 相似文献
11.
A wide variety of 3-[(alkyl/arylthio)(aryl)methyl]-1H-indole derivatives (4a–z) were synthesized through a one-pot three-component reaction from indoles, aromatic aldehydes, and thiols at room temperature using hydrated ferric sulfate as a Lewis acid catalyst. The key features of the present protocol are mild and simple reaction procedure, moderate to good yields, requirement of inexpensive and reusable catalyst, no formation of dithioacetals derivatives from the corresponding aldehydes as well as bis-(indolyl) methane derivatives. 相似文献
12.
Alexander S. Kiselyov 《Tetrahedron letters》2006,47(15):2631-2634
Reaction of N-fluoropyridinium fluoride generated in situ with a series of isonitriles and diazo compounds led to the formation of the corresponding (pyridine-2-yl)-1H-1,2,3-triazoles in good yields (37-59%). Best outcome was consistently achieved with both aromatic isonitriles and stabilized diazo derivatives. The proposed reaction mechanism involves the intermediate formation of a highly reactive carbene species. 相似文献
13.
Eight alkenes reacted with 1,1′-dithiobis(1H-1,2,4-triazole) 4 at −15 °C to form the corresponding thiiranes in moderate to good yields. The thiiranations of anti- and syn-9,9′-bibenzonorbornenylidenes and cis- and trans-cyclooctenes with 4 proceeded with retention of configuration of the starting alkenes. 相似文献
14.
A convenient method for the synthesis of substituted 2,7-naphthyridin-1(7H)-ones has been developed. This method was carried out starting from a simple nicotinamide salts via a tandem process including Reissert reaction, intramolecular nucleophilic addition and oxidation dehydrogenation. Using this method, a variety of substituted 2,7-naphthyridin-1(7H)-ones were obtained in good yields. 相似文献
15.
Nader Noroozi Pesyan Vali GolsanamlooShahnaz Ganbari Ertan ?ahin 《Tetrahedron letters》2012,53(32):4096-4099
A simple and efficient unusual coupling reaction of 9-(2-hydroxy-4,4-dimethyl-6-oxocyclohex-1-en-1-yl)-3,3-dimethyl-2,3,4,9-tetrahydro-1H-xanthen-1-one and its derivatives was accomplished in the presence of Mn2+, Cu2+, Cd2+, Hg2+, Fe3, or La3+. The structure elucidation was accomplished by IR, 1H NMR, 13C NMR, X-ray crystallography, UV-Visible and elemental analysis. A reaction mechanism is proposed. 相似文献
16.
AlCl3-mediated tandem Friedel-Crafts reaction of vinylidenecyclopropanes with acyl chlorides produced the corresponding 1-[2-(2,2-diarylvinyl)-1-phenyl-3H-inden-5-yl]ethanone derivatives in moderate to good yields under mild conditions within short reaction time. 相似文献
17.
A convenient synthetic approach to 2-[1-(dialkylamino)alkyl]-4H-3,1-benzoxazin-4-ones has been developed. Thus, 1,1-dimethylethyl 2-isocyanobenzoates, which can be readily prepared from 2-nitrobenzoic acids by a simple four-step sequence, react with N,N-dialkyliminium iodides without using any catalysts under mild conditions to give the desired products in generally fair-to-good yields. 相似文献
18.
Vakhid A. Mamedov Nataliya A. ZhukovaTat′yana N. Beschastnova Aidar T. GubaidullinDimitry V. Rakov Il’dar Kh. Rizvanov 《Tetrahedron letters》2011,52(33):4280-4284
3-Aroylquinoxalin-2(1H)-ones were found to be hetero analogues of α-diketones for the efficient, one-pot, three component synthesis of 2,4,5-trisubstituted imidazoles and imidazo[1,5-a]quinoxalin-4(5H)-ones in boiling methanol. The key advantages of this process are high yields, ready availability and low cost of 3-aroylquinoxalin-2(1H)-ones and easy work-up and separation of the products by non-chromatographic methods. Furthermore, the presence of an ortho-iminoanilide fragment at position 4 of the imidazoles obtained has made it possible to produce 2-(imidazol-4-yl)benzimidazoles in almost quantitative yields. 相似文献
19.
Ahmad Shaabani Mozhdeh Seyyedhamzeh Ali Maleki Fatemeh Hajishaabanha 《Tetrahedron》2010,66(23):4040-4167
5-Carboxamide substituted 3,4-dihydropyrimidine-2(1H)one derivatives were synthesized in a simple and efficient method from the one-pot four-component reactions of an aliphatic or aromatic amine, diketene, an aromatic aldehyde and urea or thiourea in the presence of p-toluenesulfonic acid as a catalyst under mild reaction conditions at ambient temperature. 相似文献
20.
A stereoselective total synthesis of (6R)-6-[(4R,6R)-4,6-dihydroxy-10-phenyldec-1-enyl]-5,6-dihydro-2H-pyran-2-one is reported. The strategy utilizes an iterative Jacobsen hydrolytic kinetic resolution, ring opening with a chiral propargylic synthon and a preferential (Z)-Wittig olefination reaction and lactonization as the key steps. 相似文献