- A Convenient Method for the Preparation of Nitro Olefins by Nitration of Olefins with Nitrogen Monoxide
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Olefins with a terminal double bond or conjugated with aromatic nucleus are successfully nitrated into nitro olefins in good-to-high yields on treatment with nitrogen monoxide (NO) in 1,2-dichloroethane.Nitro alcohols formed as by-products are dehydrated to yield nitro olefins by the subsequent treatment with acidic activated alumina.By GC analysis, it was confirmed that an equimolar amount of nitro gas was evolved during the present nitration.A possible reaction pathway including the formation of nitro nitroso compounds, key intermediates, is described.The key intermediates are transformed into nitro olefins by reaction with nitrogen monoxide.
- Hata, Eiichiro,Yamada, Tohru,Mukaiyama, Teruaki
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- Tertiary amine functionalized polyacrylonitrile fiber catalyst for the synthesis of tetrahydrothiophenes
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A tertiary amine immobilized fiber was prepared and used to efficiently catalyze tandem Michael-intramolecular Henry reactions between 1,4-dithiane-2,5-diol and trans-β-nitrostyrenes to form the corresponding tetrahydrothiophene derivatives. This newly developed fiber catalyst is applicable to a wide range of trans-β-nitroalkenes and affords good to excellent yields (75-93%) under mild conditions (with 2.5 mol % fiber catalyst at 50 °C in ethanol for 5 h). The fiber catalyst exhibits excellent recyclability and reusability (up to 10 times) after simple workup procedure with only a slight loss in catalytic activity. It is noteworthy that the major diastereomers have r-R, trans-nitro, trans-hydroxy configurations with diastereoselectivities of up to 15:1. This differs from the results obtained when the same reaction is catalyzed by a homogeneous catalyst. This is the first example of a fiber catalyst exhibiting excellent diastereoselectivity.
- Xu, Changzhu,Du, Jianguo,Ma, Lichao,Li, Guowei,Tao, Minli,Zhang, Wenqin
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supporting information
p. 4749 - 4757
(2013/06/27)
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- Control of functional group proximity and direction by conformational networks: Synthesis and stereodynamics of persubstituted arenes
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The cooperative nonbonded interactions present in hexaethylbenzene result in an arrangement of alkyl groups such that the 1,3,5 and 2,4,6 substituents point to opposite faces of the benzene ring. Correspondingly, derivatives of hexaethylbenzene have their functional groups convergent (meta as in 1,3,5-trisubstituted-2,4,6-triethylbenzene) or divergent (ortho, para as in 1,2-disubstituted-3,4,5,6-tetraethylbenzenes or 1,4-disubstituted-2,3,5,6-tetraethylbenzenes) due to this cooperative conformational network. To illustrate this structural feature and probe its dynamics, 1,4-di-X-2,3,5,6-tetraethylbenzenes have been synthesized. The dynamic stereochemistry of the disubstituted compounds has been studied by variable temperature 1H NMR spectroscopy. Using the same strategy, the 1,3,5-tris(CH2Y)-2,4,6-triethylbenzenes have also been prepared. The steric bulk of the substituent in the disubstituted compounds has been found to influence the barrier height. The trends found are applicable for the use of these compounds as angular building blocks for the design of ligands, polymers, and supramolecular architectures.
- Kilway, Kathleen V,Siegel, Jay S
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p. 3615 - 3627
(2007/10/03)
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