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41.
John K Gallos Vassiliki C SarliAnastassia C Varvogli Constantina Z PapadoyanniSofia D Papaspyrou Nicolaos G Argyropoulos 《Tetrahedron letters》2003,44(20):3905-3909
A new method for the stereoselective synthesis of nonproteinogenic α-amino acids has been developed, which involves hetero-Diels-Alder addition of ethyl 2-nitrosoacrylate to electron-rich alkenes, such as enol ethers, enamines and allylsilanes, and a further two or three step manipulation of the resulting oxazines. 相似文献
42.
43.
A Multicontrolled Enamine Configurational Switch Undergoing Dynamic Constitutional Exchange 下载免费PDF全文
Yansong Ren Dr. Per H. Svensson Prof. Dr. Olof Ramström 《Angewandte Chemie (International ed. in English)》2018,57(21):6256-6260
A multiresponsive enamine‐based molecular switch is presented, in which forward/backward configurational rotation around the C=C bond could be precisely controlled by the addition of an acid/base or metal ions. Fluorescence turn‐on/off effects and large Stokes shifts were observed while regulating the switching process with CuII. The enamine functionality furthermore enabled double dynamic regimes, in which configurational switching could operate in conjunction with constitutional enamine exchange of the rotor part. This behavior was used to construct a prototypical dynamic covalent switch system through enamine exchange with primary amines. The dynamic exchange process could be readily turned on/off by regulating the switch status with pH. 相似文献
44.
A new approach to the construction of polycyclic skeletons of fused azines with nitrogen at the bridgehead based on a novel
reaction of cyclic Schiff's bases (1-alkyl-substituted 3,4-dihydroisoquinolines) with α-aminomethylenecarbonyl compounds (2-aminomethylene-cyclohexane-1,3-diones
or aminomethylenemalonic ester) was developed.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1358–1360, July, 1997. 相似文献
45.
Vijay Kumar 《Tetrahedron letters》2006,47(39):7001-7005
Highly selective and efficient Michael additions of heterocyclic enamines, viz. indoles, pyrroles, and pyrazoles with α,β-unsaturated olefins using 2 mol % of ZrCl4 has been achieved. 相似文献
46.
Anton Gatial Štěpán Sklenák Viktor Milata Peter Klaeboe Stanislav Biskupič Dieter Scheller Jana Jurašková 《Structural chemistry》1996,7(1):17-36
The IR and Raman spectra of aminomethylene propanedinitrile (AM) [H2N-CH=C(CN)2], (methylamino)methylene propanedinitrile (MAM) [CH3NH-CH=C(CN)2] and (dimethylamino)methylene propanedinitrile (DMAM) [(CH3)2N-CH=C(CN)2] as solids and solutes in various solvents have been recorded in the region 4000-50 cm–1. AM and DMAM can exist only as one conformer. From the vibrational and NMR spectra of MAM in solutions, the existence of two conformers with the methyl group orientedanti andsyn toward the double C=C bond were confirmed. The enthalpy difference H
0 between the conformers was measured to be 3.7±1.4 kJ mol–1 from the IR spectra in acetonitrile solution and 3.4±1.1 kJ mol–1 from the NMR spectra in DMSO solution. Semiempirical (AM1, PM3, MNDO, MINDO3) and ab initio SCF calculations using a DZP basis set were carried out for all three compounds. The calculations support the existence of two conformersanti andsyn for MAM, withanti being 7.8 kJ mol–1 more stable thansyn from ab initio and 8.6, 13.4, 11.6, and 10.8 kJ mor–1 from AM1, PM3, MNDO, and MINDO3 calculations, respectively. Finally, complete assignments of the vibrational spectra for all three compounds were made with the aid of normal coordinate calculations employing scaled ab initio force constants. The same scale factors were optimized on the experimental frequencies of all three compounds, and a very good agreement between calculated and experimental frequencies was achieved. 相似文献
47.
V. V. Sorokin É. A. Grigor’eva N. V. Poplevina A. P. Kriven’ko S. F. Solodovnikov 《Journal of Structural Chemistry》2007,48(5):981-985
2,4-Diacetyl-5-hydroxy-5-methyl-3-phenyl-N-benzyl-1-cyclohexenylamine is obtained by benzylamination of 2,4-diacetyl-5-hydroxy-5-methyl-3-phenylcyclohexanone. Based on spectral and X-ray structural data, the half-chair conformation of the cyclohexenyl ring and the pseudoequatorial orientation of all substituents, except for the pseudoaxial OH-group, are established. An intramolecular hydrogen bond N-H...O=C is revealed. 相似文献
48.
Roman A. Kunetsky Marina I. Struchkova Vladimir A. Tartakovsky Sema L. Ioffe 《Tetrahedron letters》2005,46(31):5203-5205
An approach to conjugated nitroalkenes via oxidation of N,N-bis(silyloxy)enamines with bromine or iodine in the presence of tetra-n-butylammonium acetate is described. The acetate ion plays a key role by acting as a mild desilylating reagent. This new strategy allows the synthesis of α-nitroalkenes from the corresponding nitroalkanes. 相似文献
49.
M. A. Mzhelskaya I. D. Ivanchikova N. E. Polyakov A. A. Moroz M. S. Shvartsberg 《Russian Chemical Bulletin》2004,53(12):2798-2804
Procedures were developed for the heterocyclization of 2-benzoylethynyl-1-hydroxy-and 1-hydroxy-2-(1-oxo-3-phenylpropynyl)anthraquinone. The regioselective preparation of 2-substituted anthra[1,2-b]pyran-4,7,12-triones was demonstrated to be possible under mild conditions.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2686–2692, December, 2004. 相似文献
50.
Kh. A. Asadov F. I. Guseinov B. P. Strunin D. V. Beskrovny I. A. Litvinov 《Chemistry of Heterocyclic Compounds》2006,42(8):1059-1067
The reaction of phosphorylated α-chloroacetaldehydes with 3,4-diaminofurazane gives enamines, bisenamines, semiaminals, and
O,N-acetals, whose cyclization leads to previously unreported phosphorylated furazano[3,4-b]piperazines.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1220–1229, August, 2006. 相似文献