- Facile access to nitroalkanes: Nitration of alkanes by selective C[sbnd]H nitration using metal nitrate, catalyzed by in-situ generated metal oxide
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Direct C ? H functionalization of inactive alkanes is an important strategy to streamline the preparation of functional molecules. Herein, we describe an operationally simple and effective alkane C ? H nitration reaction to access versatile nitroalkanes without cleavage of the C ? C skeleton. Nontoxic and inexpensive metal nitrate (Fe(NO3)3·9H2O) plays a dual role as catalyst precursors as well as nitro sources for the transformation. Experimental evidence and theoretical modeling have shown the formation of iron oxide as a key catalytic species for the alkane C ? H and NO2 activation, which favors a stepwise radical mechanism with initial alkyl radical formation.
- Li, Na,Mao, Liqiu,Peng, Haoyu,Peng, Ling,Yin, Dulin,You, Kuiyi,Zhong, Wenzhou
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- Synthesis, absolute stereochemistry and molecular design of the new antifungal and antibacterial antibiotic produced by Streptomyces sp.201
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The absolute stereochemistry of the new antifungal and antibacterial antibiotic produced by Streptomyces sp.201 has been established by achieving the total synthesis of the product. A series of analogues have also been synthesized by changing the side chain and their bioactivity assessed against different microbial strains. Among them, 1e (R=C8H17) was found to be the most potent with MIC of 8μg/mL against Mycobacterium tuberculosis, 12μg/mL against Escherichia coli and 16μg/mL against Bacillus subtilis 6μg/mL against Proteus vulgaris. This was followed by 1b (R=C5H11) with MIC of 10-20μg/mL range and 1d (R=C 7H15) with MIC of 14-24g/mL, whereas 1a (R=C 4H9) and 1f (R=C18H35) were found to be completely inactive. Besides, 1c (R=C6H13) showed certain extent of antibacterial activity in the range of 24-50μg/mL. Mycobacterium tuberculosis was very sensitive to 1e (R=C8H 17) with MIC of 8μg/mL. Antifungal activity of analogues 1d (R=C7H15) and 1e, (R=C8H17) against Fusarium oxysporum and Rhizoctonia solani were found promising with MFCs in the 15-18μg/mL range.
- Boruwa,Kalita,Barua,Borah,Mazumder,Thakur,Gogoi,Bora
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p. 3571 - 3574
(2007/10/03)
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- Alkyl nitrate, hydroxyalkyl nitrate, and hydroxycarbonyl formation from the NOx-air photooxidations of C5-C8 n-alkanes
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In the troposphere, alkanes present in the gas phase react mainly with the OH radical to form an alkyl radical. Products of the gas-phase reactions of OH radicals with the n-alkanes, n-pentane through n-octane at 298 ± 2 K and 1 atm of air were studied using GC with flame ionization detection, combined GC-MS, and in situ atmospheric pressure ionization tandem MS. The alkyl nitrate, hydroxyalkyl nitrate, and hydroxycarbonyl formation yields combined with the published carbonyl yields arising from alkoxy radical decomposition and reaction with O2, account for ~ 95, ~ 80, ~ 70, and ~ 55% of n-pentane, n-hexane, n-heptane, and n-octane (with NO), respectively. Hydroxyalkyl nitrate formation accounts for a few percent of the overall reaction products, and was consistently ~ 25% of the corresponding alkyl nitrate yields. Significant fractions of the atmospheric reaction products of ≥ C5 n-alkanes (and other alkanes whose intermediate alkoxy radicals can isomerize) were composed of hydroxycarbonyls and hydroxyalkyl nitrates, compound classes which are difficult to analyze under atmospheric conditions.
- Arey,Kwok,Atkinson,Aschmann,Atkinson,Kwok,Atkinson
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p. 1020 - 1027
(2007/10/03)
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- THE C-ALKYLATION OF NITROALKANE ANIONS BY 1-SUBSTITUTED-2-T-BUTYL-4-PHENYL- AND -2,4-DIPHENYL-5,6-DIHYDROBENZOQUINOLINIUM CATIONS.
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The N-substituents are transferred from the title cations to the C-atom of nitroalkane anions in high yield at 25-80 deg C in DMSO solution.The title cations are readily available from the appropriate pyrylium cations and primary amines of types RCH2NH2 and RR'CHNH2, allowing a general 2-step method for the preparation of higher nitroalkanes.Spectral properties of a variety of nitroalkanes are discussed.
- Katritzky, Alan R.,Kashmiri, M. Akram,Wittmann, Dieter K.
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p. 1501 - 1510
(2007/10/02)
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- SYNTHESIS, PROPERTIES, AND CRYSTAL STRUCTURE OF SILYL NITRONATES (SILYL ESTERS OF ACI-NITROALKANES): TOWARDS THE SN2 REACTION PATH WITH RETENTION OF CONFIGURATION AT SILICON
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An efficient and flexible method for the preparation of silyl nitronates is described (see 1-10).NMR. spectral investigations indicate a rapid 1,3-silyl migration process, with an activation energy of about 10 kcal mol-1.X-ray crystallographic
- Colvin, Ernest W.,Beck, Albert K.,Bastani, Bahram,Seebach, Dieter,Kai, Yasushi,Dunitz, Jack D.
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p. 697 - 710
(2007/10/02)
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