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1.
A novel and efficient synthesis of N-substituted pyrrolo-pyrazinone derivatives has been developed. A trichloroacetyl group connected to the pyrrole ring was converted into the desired carboxamide derivatives. Promoted by NaH, the pyrrole carboxamide derivatives underwent a tandem reaction with propargyl bromide to afford pyrrolo-pyrazinones with high efficiency under very mild conditions. The mechanism for the formation of the products is discussed and supported by DFT calculations. 相似文献
2.
A regioselective approach was developed for the synthesis of dipyrrolo-diazepine derivatives. The synthetic route to dipyrrolo-diazepines first involves the synthesis of dipyrromethanes, followed by reaction of propargyl bromide in the presence of NaH to attach one alkyne functionality to the pyrrole nitrogen atom. Intramolecular heterocyclization with NaH in DMF between the alkyne functionality and pyrrole nitrogen atom gave the desired structures in good yields. 相似文献
3.
Paul J. Griffin Matthew A. Fava St. John T. Whittaker Kristopher J. Kolonko Arthur J. Catino 《Tetrahedron letters》2018,59(45):3999-4002
Tetraarylmethanes are an important class of molecules that contain four aryl groups bonded to a central carbon atom. The shape/three-dimensionality of these molecules makes them suitable for organic light-emitting diodes (OLEDs), organic solar cells, hydrogen storage, and even drug-delivery. Despite their importance, there are only a few methods available for their preparation. Herein, we report a simple procedure for the preparation of tetraarylmethanes that involves a bismuth-catalyzed Friedel-Crafts cyclization followed by a desulfurization reaction mediated by Raney nickel. 相似文献
4.
Hyun Seung Lee 《Tetrahedron》2008,64(10):2397-2404
N-Tosyl-3,3-disubstituted-4-vinylpyrrolidine derivatives 3a-c were synthesized via radical cyclization from the modified Baylis-Hillman adducts 2. The required starting materials 2a-c were prepared in moderate yields from the Baylis-Hillman adducts in three steps: (i) acetylation of the Baylis-Hillman adducts, (ii) SN2′ reaction with tosylamide to prepare 1, and (iii) alkylation with 1,4-dibromo-2-butene. 相似文献
5.
Fluorinated N-[2-(haloalkyl)phenyl]imidoyl chloride, which was readily available from the corresponding anilines by using Uneyama's one-pot synthesis of fluorinated imidoyl chloride, was found to be a key intermediate for the facile synthesis of 2-fluoroalkyl substituted indole derivatives via the Grignard cyclization process. The bromination of 3-methyl group of 3-methyl-2-trifluoromethyl indole with NBS/CCl4 led to the formation of 3-bromomethyl substituted indole which can be further utilized to synthesize some new and biologically interested indole derivatives. 相似文献
6.
Liang Xu 《Tetrahedron》2006,62(33):7902-7910
Various biologically important saccharin skeletons and their N-alkyl derivatives have been efficiently prepared by chromium(VI) oxide catalyzed H5IO6 oxidation of N-alkyl-o-methyl-arenesulfonamides in acetonitrile. N-tert-Butyl saccharin skeletons were easily prepared by H5IO6-CrO3 oxidation of N-tert-butyl-o-methyl arenesulfonamides in the presence of acetic anhydride. The method that furnished the novel fluoro and trifluoromethyl substituted saccharin skeletons is characterized by two steps, a simple work-up procedure, a single purification and good overall yields from substituted toluene derivatives. 相似文献
7.
The hitherto unknown lactone 5H-pyrrolo[1,2-a][3,1]benzoxazin-5-one and six of its substituted derivatives have been prepared by active manganese dioxide promoted oxidative cyclization of the corresponding 2-(1H-pyrrol-1-yl)benzoic acids, under mild conditions, in moderate yields. The method was successfully extended to the cyclization of some ortho-(1H-pyrrol-1-yl)heteroaryl carboxylic acids and 2-(1H-indol-1-yl)benzoic acids. 相似文献
8.
Christian Hobson Michael S. Perryman Gavin Kirby Guy J. Clarkson David J. Fox 《Tetrahedron letters》2018,59(44):3965-3968
Enantiomerically-enriched secondary trichloromethyl-alcohols react with aryl amines to give enantiomerically-enriched α-N-arylamino-acid derivatives. The intermediate acid chlorides can react in situ with aryl or, regioselectively, with alkyl amines to give aryl or alkyl α-N-arylamino amides. 相似文献
9.
Savitha GurunathanParamasivam Thirumalai Perumal 《Tetrahedron letters》2011,52(15):1783-1787
Facile synthesis of novel 3-bromo-1,2-dihydroquinolines by the intramolecular cyclization of N-tosyl-N-propargyl anilines catalyzed by Pd(OAc)2 in conjunction with CuBr2 and LiBr. 相似文献
10.
Jianguang Lv Zhiqing He Jianmin Zhang Yuwei Guo Ziwei Han Xinhua Bao 《Tetrahedron》2018,74(29):3996-4004
A simple and efficient copper-catalyzed tandem radical cyclization reaction has been discovered for the synthesis of triaryl [1,2,4]triazolo[1,5-a]pyridines from easily accessible azines and benzylidenmalononitriles. The new transformation involves multiple CH/CC bonds cleavage and CC/CN bonds formation, with extrusion of gaseous hydrogen and methane. A wide variety of substrates with different functional groups could be converted into the corresponding products in good yields. The fused heterocycles have strong blue fluorescence with large Strokes shifts and high quantum yields. 相似文献
11.
Ramapanicker Ramesh 《Tetrahedron》2007,63(37):9153-9162
The base catalyzed cyclization of N-aryl and N-alkyl-O-propargyl carbamates is studied in detail. The effect of various bases and solvents on the efficacy of this cyclization reaction is analyzed and a new base-solvent system (LiOH in DMF) for effective cyclization of these carbamates is reported. A number of differentially substituted O-propargyl carbamates were cyclized to the corresponding 2-oxazolidinones under these conditions. The reaction conditions reported here are mild and no side reactions were observed in any of the substrates studied. A propargyl carbonate group was unaffected during the course of the cyclization of the O-propargyl carbamate group. The propargyl carbamates were prepared from the corresponding alkyl or aryl amines and the corresponding propargyl chloroformate, resulting in oxazolidinones diversely substituted at the nitrogen atom. N-Aryl-O-propargyl carbamates cyclized readily to the corresponding oxazolidinones with LiOH in DMF, whereas N-alkyl-O-propargyl carbamates reacted slowly under the same conditions. O-Propargyl carbamates substituted at the 1-position tend to cyclize faster whereas those substituted at 3-position cyclize considerably slower than the unsubstituted carbamates. 相似文献
12.
Employing N-(4,5-dihydrooxazol-2-yl)benzamide as novel and efficient ligand, the copper-catalyzed intramolecular cyclization of various substituted 1-acyl-3-(2-bromophenyl)thioureas could be successfully carried out under mild conditions. A variety of N-benzothiazol-2-yl-amides were synthesized in good to excellent yields. 相似文献
13.
Kazuhiro Kobayashi Atsushi Takanohashi Kenichi Hashimoto Osamu Morikawa Hisatoshi Konishi 《Tetrahedron》2006,62(44):10379-10382
A facile synthetic method for 4,5-diaminopyrrolo[1,2-a]quinoline derivatives has been developed. Treatment of 2-(pyrrol-1-yl)benzaldehydes with secondary amine hydrochloride/NaI/TMSCl/Et3N in the presence of an isocyano compound leads to the formation of 4-alkyl(or aryl)amino-5-dialkylaminopyrrolo[1,2-a]quinolines. 相似文献
14.
Optimization details and limitations of a novel synthetic method of 4-tert-butyl 2-ethyl 3-amino-1-benzyl-5-dialkylamino-1H-pyrrole-2,4-dicarboxylate derivatives are herein disclosed. This synthesis consists of four steps that include a highly selective cyclization, and can be carried out from starting materials to target compounds without column chromatography purification. The high selectivity is controlled by lithium coordination and steric hindrance caused by tert-butyl ester. 相似文献
15.
Hyun Seung Lee 《Tetrahedron letters》2009,50(19):2274-9061
An expedient method was developed for the synthesis of 1,4,5,6-tetrahydropyridines by radical cyclization protocol involving consecutive 1,5-hydrogen transfer and double bond isomerization process starting from Baylis-Hillman adducts. 相似文献
16.
Nitin T. Patil 《Tetrahedron letters》2004,45(46):8497-8499
An efficient method for the allylation of C, N, and O-nucleophiles with alkynes under solvent-free conditions and by microwave activation is established. The process can be termed as a real eco-chemical process since no waste elements are produced in the reaction, moreover it is solvent free. This technique can also be used for the allylation of dimethyl methylmalonate, which proves inert under the previously reported reaction conditions (refluxing in 1,4-dioxane). 相似文献
17.
Rafaela G.M. da Costa Francisco R.L. Farias Davi Back Jones Limberger 《Tetrahedron letters》2018,59(8):771-775
A useful protocol for arylation of the olefin double bond of chalcones to afford tri- and tetra-substituted chalcone derivatives is reported. The protocol begins with the Heck reaction between chalcones and aryl iodides providing β-arylchalcones. This reaction tolerates various functional groups on both rings, as well as deactivated aryl iodides. The products are obtained in moderate to excellent yields and the (E)-β-arylchalcones (E:Z?>?96:4) can be isolated via precipitation. Competitive Heck reactions pointed to a significant effect of ring one substituents on the reaction rate, while substituents on ring two have a much smaller effect. To access α,β-diarylchalcones, a sequential bromination-Suzuki cross coupling strategy was applied to the β-arylated compounds which afforded double arylated chalcone derivatives in 60–99% yield over two steps. 相似文献
18.
An efficient I2/TBHP-mediated process for the formation of furo[3,2-c]coumarins from readily available materials has been developed. This process for the formation of furo[3,2-c]coumarins is quite environmental friendly and atom-economical. 相似文献
19.
Indene derivatives including an allene functional group are readily prepared in moderate to excellent yields with high regioselectivity under very mild reaction conditions by the Pd/C-catalyzed reaction of propargylic compounds. The resulting products can be further elaborated using Pd-catalyzed annulation reactions. 相似文献
20.
Harry H. Wasserman Mingde Xia Jianji Wang Anders K. Petersen Michael Jorgensen Patricia Power Jonathan Parr 《Tetrahedron》2004,60(34):7419-7425
Reaction of the tert-butyl ester of 3-methoxy-2-pyrrole carboxylic acid with singlet oxygen yields a peroxidic intermediate which undergoes coupling with a range of nucleophiles to yield 5-substituted pyrroles. Among these products are α,α′-bipyrroles which serve as precursors of prodigiosin, including A-ring substituted analogues. 相似文献