- A Stereoconvergent Synthesis of (+)-4-Demethoxydaunomycin
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Sharpless kinetic asymmetric epoxidation on (+/-)-2-(1-hydroxyethyl)-5,8-dimethoxy-3,4-dihydronaphthalene followed by LiAlH4 reduction gave R-(-)-2-(S-1-hydroxyethyl)-2-hydroxy-5,8-dimethoxy-1,2,3,4-tetrahydronaphthalene and the undesired antipode: the former was converted into R-(-)-2-acetyl-2-hydroxy-5,8-dimethoxy-1,2,3,4-tetrahydronaphthalene while the latter was epimerized and recycled.
- Rao, A. V. Rama,Yadav, J. S.,Reddy, K. Bal,Mehendale, A. R.
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- 1H-Cyclopropanaphthalene-3,6-dione
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Cerium ammonium nitrate demethylation and oxidation of 3,6-dimethoxy-1H-cyclopropanaphthalene 6 provides 1H-cyclopropanaphthalene-3,6-dione 8 as the first stable cyclopropaquinone.
- Halton, Brian,Kay, Andrew J.,Zhi-mei, Zha
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- Synthesis of poly(decahydro-2-naphthyl methacrylate)s with different geometric structures and effects of side-group dynamics on polymer properties investigated by thermal and dynamic mechanical analyses and DFT calculations
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We prepared the geometric isomers of decahydro-2-naphthols as the source materials for the synthesis of poly(decahydro-2-naphthyl methacrylate)s [poly(DNMA)-I, -II, -III, and -IV] including alicyclic ester groups with different geometric structures. The geometry and conformational dynamics of the decahydro-2-naphthyl moieties were investigated by NMR spectroscopy and DFT calculations. We synthesized each isomer of the methacrylic monomers, polymerized them, and investigated the optical, thermal, and mechanical properties of poly(DNMA)s with different isomer compositions. The Tg values of the poly(DNMA)s were in the following order: 139.3 C for poly(DNMA)-II 3/g, 1.489, and 42-44, respectively.
- Ozaki, Anri,Sumita, Koha,Goto, Kunihiro,Matsumoto, Akikazu
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p. 2941 - 2950
(2013/06/05)
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- Spectroscopic and X-ray crystallographic evidence for electrostatic effects in 4-substituted cyclohexanone-derived hydrazones, imines, and corresponding salts
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The axial conformer of several 4-substituted cyclo-hexanone hydrazone salts was found to predominate in solution. Changes in the charge of the molecule and the polarity of the solvent led to changes in the conformational preference of each molecule that were consistent with electrostatic stabilization of the axial conformer. H NMR spectroscopic analysis was utilized to determine the structure of cyclohexanone-derived substrates by comparison to conformationally restricted trans-decalone derivatives and computational models. X-ray crystallography demonstrated that the axial configuration of a pendant benzyloxy group is the preferred conformation of an iminium ion in the solid state. The structure of a neutral hydrazone was also determined to favor the axial configuration for a pendant benzyloxy group in the solid state.
- Dibble, David J.,Ziller, Joseph W.,Woerpef
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experimental part
p. 7706 - 7719
(2011/12/02)
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- The stereoselectivity of addition of benzoyloxyl radicals to trans-Δ2-octalin
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The stereochemistry of addition of benzoyloxyl radicals to the conformationally rigid cyclohexene, trans-Δ2-octalin, in the presence of the free radical scavenger 1,1,3,3-tetramethyl-2,3-dihydro-1H-isoindol-2-yloxyl, is reported. Axial addition was favoured over equatorial addition with modest selectivity (axial:equatorial = 1.7:1.0). The aminoxyl trapping reaction was more selective with a ratio of trans: cis addition of 4.4:1.0. Interestingly, when the benzoate group is axial, axial trapping by the sterically hindered aminoxyl is strongly favoured (axial:equatorial = 7.4:1.0), whereas when the benzoate group is equatorial, there is only a small preference for equatorial trapping by the aminoxyl (equatorial:axial = 2,4:1.0). The structures of the four possible addition products were determined by 1H and 13C NMR spectroscopy, and confirmed in the case of the diaxial addition product [2(ax)-benzoyloxy-3(ax)-(1,1,3,3-tetramethyl-2,3-dihydroisoindol-2-yloxy)-trans- decalin 3] by X-ray crystallographic analysis.
- Busfield, W. Ken,Byriel, Karl A.,Grice, I. Darren,Jenkins, Ian D.,Lynch, Daniel E.
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p. 757 - 760
(2007/10/03)
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- Total Synthesis of (+/-)-4-Demethoxydaunomycinone
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2-Acetyl-5,8-dimethoxy-1,2,3,4-tetrahydro-2-naphthol (4), the key synthon for the total synthesis of various antitumor anthracyclinones, has been prepared either from 1,4-dimethoxynaphthalene and making use of metal-ammonia reduction or from benzoquinone and going through Diels-Alder reaction with 1,3-butadiene. 4 is then converted into (+/-)-4-demethoxydaunomycinone (3b).
- Rao, A. V. Rama,Deshpande, V. H.,Sathaye, K. M.,Jaweed, S. M.
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p. 697 - 702
(2007/10/02)
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