نتایج جستجو برای: dihydropyran
تعداد نتایج: 69 فیلتر نتایج به سال:
A novel series of biscoumarin (1-4) and dihydropyran (5-13) derivatives were synthesized via a one-pot multicomponent condensation reaction and evaluated for antibacterial and antitumor activity in vitro. The X-ray crystal structure analysis of four representative compounds, 3, 7, 9 and 11, confirmed the structures of these compounds. Compounds 1-4 showed the most potent antitumor activity amon...
1,3-Dipolar cycloaddition of dihydropyran derived nitrones synthesized from 2,3 dihydro 4H-pyran and various hydroxylamines, with electron deficient alkynes are found to have significant rate acceleration and improved yields of isoxazolines in 1-Butyl-3-methylimidazolium based ionic liquids while with enals exclusively endo isoxazolidines are obtained with high selectivity. Synthetic potentiali...
Five new pyran rings containing polyketides, penicipyrans A-E (1-5), together with the known pestapyrone A (6), were isolated from the saline soil-derived Penicillium raistrickii. Their structures were determined by interpretation of NMR and HRESIMS data. The absolute configurations of compounds 4 and 5 were established by the modified Mosher's method and single-crystal X-ray diffraction analys...
catalytic amount of ce(iv) as ceric triethylammonium nitrate (ctean) in dichloromethane or acetone can bring about an efficient tetrahydropyranylation of different types of alcohols to afford the corrsesponding tetrahydropyranyl ethers in high yields. deportection of tetrahydropyranyl ethers can also be achieved efficiently in the presence of this catalyst in methanol.
Upon Brønsted base organocatalysis, ketone-derived alkylidene Meldrum's acids proved to be competent vinylogous platforms able undergo a formal (4+2) cycloaddition reaction with dihydro-2,3-furandione, providing an unprecedented route 3,6-dihydropyran-2-ones as spiro[4.5]decane derivatives up 98 % ee thanks the commercially available Takemoto catalyst. Preliminary investigation showed that this...
The 2,3,4-tri-toluenesulfonate ester derivatives of the methyl pyranosides of l-arabinose, d-ribose, d-lyxose, and d-xylose have been prepared, and their substitution reactions with various nucleophiles have been examined. For arabinose, xylose, and ribose, highly regioselective monosubstitutions were observed with benzoate, nitrite, and azide anions. These reactions have led to short and simpl...
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