- Dehydrogenation of Nitrogen Heterocycles Using Graphene Oxide as a Versatile Metal-Free Catalyst under Air
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Graphene oxide (GO) has been developed as an inexpensive, environmental friendly, metal-free carbocatalyst for the dehydrogenation of nitrogen heterocycles. Valuable compounds, such as quinoline, 3,4-dihydroisoquinoline, quinazoline, and indole derivatives, have been successfully used as substrates. The investigation of various oxygen-containing molecules with different conjugated systems indicated that both the oxygen-containing groups and large π-conjugated system in GO sheets are essential for this reaction. (Figure presented.).
- Zhang, Jingyu,Chen, Shiya,Chen, Fangfang,Xu, Wensheng,Deng, Guo-Jun,Gong, Hang
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p. 2358 - 2363
(2017/07/22)
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- Acid catalysed reaction of indanones, tetralones and benzosuberone with neopentyl glycol and other alkanediols under forced conditions
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Upon reaction with an excess of 2,2-dimethylpropane-1,3-diol (neopentyl glycol, NPG) under acid catalysis, indanones and tetralones yield indenes and dihydronaphthalenes, respectively. The reaction can also be carried out with butane-1,3-diol.
- Imai, Masao,Morais, Goreti Ribeiro,Al-Hindawi, Bassam,Al-Sulaibi, Mazen A.M.,Meetani, Mohammad,Thiemann, Thies
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experimental part
p. 325 - 329
(2010/10/19)
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- Synthesis of (±)-trans-7,8-dihydrodiol of 6-fluoro-benzo[a]pyrene via hydroxyl-directed regioselective functionalization of substituted pyrene
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Synthesis of (±)-trans-7,8-dihydroxy-6-fluoro-7,8- dihydrobenzo[a]pyrene, the metabolite from 6-fluoro-benzo[a]pyrene, is described. Position 6 of 7,8,9,10-tetrahydrobenzo[a]pyren-7-ol (1) was functionalized by bromination with N-bromosaccharin. Regioselectivity in the bromination is thought to derive from a substrate-reagent hydrogen bond. NMR evidence is offered to support this model. The 6-bromo derivative 2 was subjected to dehydration followed by bromine-lithium exchange. Quenching the lithio intermediate with NFSi afforded the 6-fluoro derivative 4. Prevost reaction on the 7,8 double bond resulted in the trans dibenzoate 5 (established by comparison to a cis derivative prepared by osmium tetroxide cis dihydroxylation). Introduction of the 9,10 double bond by a bromination- dehydrobromination procedure, followed by hydrolysis, gave racemic trans- 7,8-dihydrodiol 7. Resolution of the enantiomers was achieved by chiral HPLC, and the absolute configurations of the early and late eluting isomers were determined through CD spectroscopy by comparison with the metabolically obtained (7R,8R)-dihydrodiol.
- Zajc, Barbara
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p. 1902 - 1907
(2007/10/03)
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- Preparation of Enantiomers of (+/-)-trans-7β,8α-Dihydroxy-9α,10α-epoxy-7,8,9,10-tetrahydrobenzopyrene
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(+/-)-trans-7,8-Dihydroxy-7,8-dihydrobenzopyrene (VII), obtained from 7,8,9,10-tetrahydrobenzopyrene-7(8H)-one (I) by modifications and improvements of the reported procedures, has been converted into its di-(-) and (+)-menthoxyacetate derivatives in 82percent yield.The diastereomers have been separated by liquid chromatography on Lichrosorp Si 60 (30μ) column (100 cm x 1 cm dia.) using methylene chloride-ethyl acetate (99.4/0.6, v/v) as eluant.The enantiomers are liberated from the separated diastereomers by methanolysis with catalytic amount of sodium methoxide and converted into the enantiomers of (+/-)-trans-7β,8α-dihydroxy- 9α,10α-epoxy-7,8,9,10-tetrahydrobenzopyrene by m-chloroperbenzoic acid in an overall yield of 30percent.The CD and the UV spectra of the diastereomers and the enantiomers are reported.
- Iyer, Radhakrishnan P.,Slaga, Thomas J.,Pal, Bimal C.
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p. 275 - 278
(2007/10/02)
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