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Jackson Chi-San Chen 《Journal of organometallic chemistry》1978,156(1):213-219
The hydroboration of 3-butenyl derivatives, CH2CHCH2CH2X where X represents OH, OMe, OAc, Cl, as well as the related carboxylic ester, CH2CHCH2COOEt, and the nitrile CH2CHCH2CN, with 9-borabicyclo[3.3.1]nonane (9-BBN) proceeds with remarkably high regio-selectivity. The boron is placed essentially on the terminal carbon (?98%), yielding stable organoboranes which can be readily oxidized to alcohols or subjected to other reactions. The yields of alcohols in the hydroboration-oxidation procedure are satisfactory, in the range of 82–99%. The hydroxy group liberates hydrogen rapidly and quantitatively but no further reaction is observed and hydroboration of the carboncarbon double bond then proceeds normally. The chloro and methoxy groups are not affected by 9-BBN, whereas, the ester and nitrile groups are slightly (1.5–4.0%) reduced by the reagent at 25°C. Even this small amount of reduction can be circumvented or minimized by carrying out the hydroboration at 0°C. Although this procedure requires somewhat longer reaction times, the products are cleaner and the yields are higher. 相似文献
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《Tetrahedron letters》1987,28(39):4575-4578
Carboxylic acids are readily reduced to the corresponding aldehydes in high yields by treatment of acyloxy-9-borabicyclo[3.3.1]nonanes with lithium 9-boratabicyclo[3.3.1]nonane (Li 9-BBNH) at room temperature. 相似文献
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[reaction: see text] Benzylboranes are noticeably uncommon partners within Suzuki-Miyaura coupling reactions. B-Benzyl-9-BBN was successfully coupled to a range of aryl/heteroaryl bromides, chlorides, and triflates to give pharmacologically important methylene-linked biaryl structures. Activated, deactivated, and sterically hindered substrates were successfully coupled in high yield using Pd(PPh(3))(4) or Pd(OAc)(2) with SPhos as the catalyst system. 相似文献
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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
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Conformations of 3-borabicyclo[3.3.1]nonane derivatives have been studied by means of 1H and 13C NMR spectroscopy. With the aid of the coupling constants 3J(HH) and 13C chemical shifts it has been shown that all the derivatives of 3-borabicyclo[3.3.1]nonane with the trigonal boron atom studied are in a flattened double-chair conformation. In 3-borabicyclo[3.3.1]nonane derivatives with the tetra-coordinated boron atom and substituents at the 7α-position, the chair-boat conformation predominates, the boat conformation being characteristic of the cyclohexane ring; exceptions are the compounds with the internal donor—acceptor bond between the boron atom an 7α-substituent. 相似文献
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Facile and convenient synthesis of B-amino-9-borabicyclo[3.3.1]nonanes. Aminoboration of lsocyanates
Bakthan Singaram 《Heteroatom Chemistry》1992,3(3):245-249
The reaction of 9-borabicyclo[3.3.1]nonane (9-BBN) with aliphatic and aromatic primary and secondary amines in tetrahydrofuran (THF) at 65°C proceeds rapidly and quantitatively with evolution of hydrogen and the formation of the corresponding B-amino-9-borabicyclo[3.3.1] nonane (B-amino-9-BBN). Simple evaporation of THF from the reaction mixture gives the B-amino-9-BBN derivatives in high yield and purity. These B-amino-9-BBN derivatives are reactive towards alkyl and aryl isocyanates. Consequently, the aminoboration of various isocyanates has been studied using B-phenylamino-9-BBN. Thus, two equivalents of isocyanates react with one equivalent of B-phenylamino-9-BBN to afford, following the hydrolysis of the intermediate with ethanolamine, N, N'-disubstituted-N -(phenylamido)-ureas in excellent yields. A plausible mechanism for this aminoboration reaction of isocyanates is also presented. 相似文献
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M.Vivekananda Bhatt 《Journal of organometallic chemistry》1978,156(1):221-226
In methylene chloride solution, B-bromo-9-borabicyclo[3.3.1]nonane (BBr-9-BBN) readily cleaves, in excellent yield, a variety of ethers of representative structural types. The reagent can also be used for selective cleavage of one of the ether groups in a molecule containing more than one such group. 相似文献
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Suzuki coupling reaction for the solid-phase preparation of 5-substituted nicotinic acid derivatives
Joan-Carles Fernàndez Laia Solé-Feu Natalia de la Figuera Fernando Albericio 《Tetrahedron letters》2005,46(4):581-585
The application of the Suzuki coupling reaction to the preparation of small combinatorial libraries using 5-bromonicotinic acid as a scaffold onto three different types of solid support (Wang, Rink, and BAL resin) is described. 相似文献
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《Journal of organometallic chemistry》1987,322(1):25-32
Tricyclic heterocycles (8) containing a stannacyclopentadiene unit are obtained as the major products (ρ 80%) from the reaction between diethynyldimethylstannane and B-alkyl-9-borabicyclo[3.3.1]nonanes (2). By comparison with the analogous reaction of ethynyltrimethylstannane (1) it is shown that compounds 8 are the kinetically controlled products. Assignments of the structure of 8 and those of some minor products are based on multinuclear NMR spectra (1H, 11B, 13C, 119Sn NMR). 相似文献
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M.E. Gurskii S.V. Baranin A.S. Shashkov A.I. Lutsenko B.M. Mikhailov 《Journal of organometallic chemistry》1983,246(2):129-139
The ate complexes of 7-substituted 3-alkyl-3-borabicyclo[3.3.1]nonanes and of 3-alkyl-3-borabicyclo[3.3.1]non-6-enes react with acetyl chloride under mild conditions by an intermolecular β-hydride transfer mechanism to form 5-substituted 3-methylenecyclohex-1-ylmethyl(dialkyl)boranes. The latter compounds were converted, by oxidation with alkaline hydrogen peroxide, to 3-substituted 1-methylene-5-hydroxymethylcyclohexanes. The reaction of cycloalkylmethyl(dialkyl)boranes with aromatic aldehydes was applied to the synthesis of 1,3-di- and 1,3,5-tri-methylene derivatives of the cyclohexane series. 相似文献
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Mikhail E. Gurskii Ilya D. Gridnev Yuri N. Bubnov Andrew Pelter Paul Rademacher 《Journal of organometallic chemistry》1999,590(2):227
3-Methoxy-7α-phenyl-1,5-dimethyl-3-borabicyclo[3.3.1]nonane 5 in solution at room temperature exists in the double chair conformation, as shown by NMR studies. Increasing the temperature leads to an increase in the population of the chair–boat conformation. At decreased temperature hindered rotation around the B---O bond is observed for 5. Dissolving 5 in deuteropyridine leads to the reversible formation of complex 6, which exists in the chair–boat conformation. The chair–boat conformation is also the most stable one for chelate compound 7 with a tetracoordinated boron atom. 相似文献
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M. E. Gurskii P. A. Belyakov K. A. Lyssenko A. L. Semenova Yu. N. Bubnov 《Russian Chemical Bulletin》2014,63(2):480-486
2D 1H-1H EXSY NMR spectroscopy show that the free energy of activation ΔG ≠ in six 3-allyl-3-borabicyclo[3.3.1]nonane derivatives is significantly higher (72–86 kJ mol?1) than that in typical allylboranes (48–66 kJ mol?1). For the first member of the series, viz., 3-allyl-3-borabicyclo[3.3.1]nonane, the activation parameters of the permanent allylic rearrangement were also determined (ΔH ≠ = 82.7±3.4 kJ mol?1, ΔS ≠ = ?11.8±10.3 J mol?1 K?1, E A = 85.5±3.4 kJ mol?1, lnA = 29.2±1.2). 相似文献
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Summary: The preparation of polystyrene block methyl methacrylate copolymers (PS-b-PMMA) is described. The polystyrene segment was prepared by anionic polymerization and the methylmethacrylate segment was prepared via free radical autoxidation of a borane agent attached to the styrene chain. 1 The chemistry involves a transformation of the anionic polymerization process to borane chemistry by firstly producing polystyrene with chain end unsaturated alkyl functional groups prepared using a n-butyllithium initiator and termination with allylchlorodimethylsilane. Secondly, the unsaturated macroinitiator end was hydroborated by 9-borabicyclo[3.3.1]nonane (9-BBN) to produce a borane terminated PS. Thirdly, the borane group at the chain end was selectively oxidized and converted to polymeric radicals in the presence of methyl methacrylate which then initiated radical polymerization to produce block copolymers. The polymer obtained was characterized using several chromatographic techniques including LC-CC (liquid chromatography under critical conditions) for the polystyrene segments and two-dimensional chromatography with LC-CC in the first dimension and SEC in the second. The results show that block formation was successful although significant homopolymerization of methyl methacrylate is also obtained. 相似文献
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Conclusions Two consecutive -hydride elimination reactions in borate complexes derived from 3-bora-bicyclo[3.3.1]non-6-ene gave derivatives of 3-methylenecyclohexene and 3,5-dimethylenecyclo-hexene.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2625–2627, November, 1987. 相似文献
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[reaction: see text] Interest in bicyclic natural products from the Guttiferae classification has led to the development of an improved method for the selenium-mediated cyclization of alkenyl-substituted beta-dicarbonyls (I) to form a variety of bicyclo[3.3.1]nonan-9-ones (II) both in solution and on solid support. 相似文献