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991.
M. E. Gurskii K. A. Lyssenko A. L. Karionova P. A. Belyakov T. V. Potapova M. Yu. Antipin Yu. N. Bubnov 《Russian Chemical Bulletin》2004,53(9):1963-1977
The conformational equilibrium in solution was examined by NMR spectroscopy for a series of 7-phenyl-3-borabicyclo[3.3.1]nonane derivatives containing various substituents at the boron atom. The structures of these derivatives were studied in the crystalline state (X-ray diffraction analysis) and by quantum-chemical calculations (B3Pw91/6-31G*). The B...Ph transannular interactions corresponding to charge transfer from the system of the phenyl group to the vacant p-orbital of the B atom were demonstrated to be responsible for unique stability of the chair-chair conformation of these derivatives.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1884–1896, September, 2004. 相似文献
992.
The selenenylation of racemic and optically active α-phosphoryl sulfoxides is a key step leading efficiently to α-phosphorylvinyl sulfoxides or α-phosphorylvinyl selenides depending on the reaction conditions. Oxidation of α-phosphorylvinyl selenides and subsequent thermolysis of selenoxides afford alkynylphosphonates. Studies of the stereochemical course of nucleophilic addition to α-phosphoryl sulfoxides show high facial stereoselectivity of the reaction, however, epimerisation at the α-carbon atom leads to mixtures of diastereomers. 相似文献
993.
994.
We have developed a method for obtaining 2-substituted 3-amino-6,6-dimethyl-5,6-dihydro-8H-pyrano[4′,3′:4,5]-and 5,6,7,8-tetrahydrobenzo[b]thieno[2,3-d]pyrimidin-4(3H)-ones,
converted by deamination to the corresponding dihydropyranothieno-3H-pyrimidinones.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 441–444, March, 2006. 相似文献
995.
《Electroanalysis》2006,18(17):1681-1688
Acidic treated multiwalled carbon nanotubes (AMWNTs) were ground with water‐miscible room temperature ionic liquids, 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([bmim]BF4), and resulted in AMWNTs‐[bmim]BF4 composite. Its electrical‐ionic conductivity and optical properties were compared with the other two types of carbon materials‐[bmim]BF4 composites: pyrolytic graphite powder (PGP), pristine multiwalled carbon nanotubes (PMWNTs), through the ac impedance technology and Raman spectroscopy. The impedance data show that AMWNTs‐[bmim]BF4 composite exhibits the highest conductivity. Raman spectra study exhibits that the [bmim]BF4 can form gel with PMWNTs and AMWNTs but only form a viscous liquid with PGP. AMWNTs‐[bmim]BF4 gel modified GC electrode was applied in direct electrochemistry of heme proteins (Hb and HRP) and it catalysis to the reduction of H2O2 was investigated. 相似文献
996.
The reactions of N-methylmorpholinium 6-amino-3,5-dicyano-1,4-dihydropyridine-2-thiolates with formaldehyde and primary aromatic amines produce
3,5,7,11-tetraazatricyclo[7.3.1.02,7]tridec-2-ene-1,9-dicarbonitrile derivatives.
For Part 1, see Ref. 1.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2605–2607, November, 2005. 相似文献
997.
Mickaël Pauvert Sylvain C. Collet André Y. Guingant Michel Evain 《Tetrahedron letters》2005,46(17):2983-2987
Addition of cyanide ion to chiral N-acyl-quinolinium and N-acyl-isoquinolinium salts led selectively to 1,2-addition products. Removal of the chiral auxiliary affords the title compounds in pure enantiomeric form. 相似文献
998.
Poly[N-(2-aminoethyl)acrylamido]trimethyl ammonium chloride resin was developed as a new polymeric phase transfer catalyst. This quaternized polyacrylamide catalyzed the chemoselective reduction of aldehydes and ketones by NaBH4 to give corresponding alcohols in high yields under mild conditions. 相似文献
999.
Dragana TadicJoannes T.M Linders Judith L Flippen-Anderson Arthur E JacobsonKenner C Rice 《Tetrahedron》2003,59(25):4603-4614
Two of the 12 possible oxide-bridged phenylmorphans, were synthesized, rac-(3R,6aS,11aS)-2-methyl-1,3,4,5,6,11a-hexahydro-2H-3,6a-methanobenzofuro[2,3-c]azocine-10-ol (7) (the ortho-c compound), and rac-(3R,6aS,11aS)-2-methyl-1,3,4,5,6,11a-hexahydro-2H-3,6a-methanobenzofuro[2,3-c]azocine-8-ol (8) (the para-c compound). Single-crystal X-ray diffraction studies indicated that the dihedral angle between the least squares planes through the phenyl ring and the atoms C1, C11a, C12, and C3 in the piperidine ring in both 7·CHCl3 and 8·HBr was 6.9°. The C12-C6a-C6b-C10a torsion angle was found to be 139.3° for both compounds. The angular relationship between the phenolic ring and the piperidine ring in phenylmorphans that interact with specific opioid receptors as agonists or antagonists is of considerable theoretical interest. 相似文献
1000.
Hai Bing LI Yuan Yin CHEN* Shu Ling GONG Department of Chemistry Wuhan University Wuhan 《中国化学快报》2002,13(3)
Calix [n] arenas {n = 4, 6 or 8} are easily prepared from formaldehyde and para-substituted phenols via cyclic condensation under alkaline conditions in one step. It is not surprising that the calyx [n] arene (n = 4, 6, 8) chemistry has been developing very rapidly during the latest 20 years1. However, it is not the case for calixarenes with odd benzene rings (for example, n = 5). The yield of p-tert-butylcalix [5] arene synthesized in one-step from p-tert-butylphenol and formaldehyde was a… 相似文献