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Dynamic NMR study of dinitrophenyl derivatives of seven‐membered cyclic ketals of pyridoxine 下载免费PDF全文
Ilfat Z. Rakhmatullin Leisan F. Galiullina Marsel' R. Garipov Alexey D. Strel'nik Yurii G. Shtyrlin Vladimir V. Klochkov 《Magnetic resonance in chemistry : MRC》2015,53(10):805-812
Two pyridoxine derivatives containing a dinitrophenyl moiety were investigated by 1H NMR spectroscopy. Conformational dynamics in solution were studied for each compound using dynamic NMR experiments. It was shown that both compounds studied are involved into two conformational exchange processes. The first process is a transformation of the seven‐membered cycle conformation between the enantiomeric P‐twist and M‐twist forms, and the second is a rotation of the dinitrophenyl fragment of the molecules around the C–O bond. Energy barriers of both conformational transitions were determined. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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A novel carbon based strong solid acid catalyst has been synthesized successfully. The catalytic activity for acetalization and ketalization was investigated. The results showed that the novel catalyst was very efficient with the average yield over 92%. The novel heterogeneous catalyst also has the advantages of high activity, wide applicability even to the preparation of 7 membered ring acetals and ketals, strikingly simple workup procedure, non-pollution and reusability, which will contribute to the green process greatly. 相似文献
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M. M. Lakouraj M. Tajbakhsh V. Khojasteh M. H. Gholami 《Phosphorus, sulfur, and silicon and the related elements》2013,188(12):2645-2651
Efficient conversion of acetals, ketals, and diacetates to carbonyl compounds is described using Caro's acid supported on silica gel. The deacetalization reactions are carried out in acetonitrile at room temperature. Reaction of diacetates is performed in refluxing dichloromethane, and their parent carbonyl compounds are obtained in good-to-excellent yields. 相似文献
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Xanthone, as its dimethyl ketal, undergoes functionalization with a synthetically useful degree of regioselectivity using a lithiation protocol. The core structure is regenerated during the work-up. Monosubstitution at C-4 or C-1 and disubstitution at C-4 and C-5 or C-1 and C-5 are observed. The substitution pattern appears to be dependent upon the experimental conditions. 相似文献
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Novel 2,2‐bis‐C‐functionalized chain glucosid‐3‐uloses have been synthesized in the form of ketal. The synthesis is rather convenient through one pot multistep reactions and no expensive reagents are involved. The products are formed via autoxidation‐Michael addition mechanism and their structures were characterized by X‐ray crystallographic analysis. Their crystal stuctures are stablilized by intermolecular hydrogen bonds and double‐strand supramolecular stacking is observed. 相似文献
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Carolyn Selenski 《Tetrahedron》2006,62(22):5298-5307
We report the synthesis of diinsininone (33), the aglycone of (±)-diinsinin (2). Thereby, we complete the first construction of a proanthocyanidin (PA) type-A compound incorporating a [3.3.1]-bicyclic ketal as its characteristic core. Our strategy utilizes a coupling between a benzopyrilium salt and a flavanone that proves applicable to other PA type-A compounds. During this undertaking, treatment of naringenin (9) with 2-iodoxybenzoic acid (IBX) followed by reductive work-up affords eriodictyol (10). This reactivity mirrors that of catechol hydroxylase (F3H) found in the flavonoid pathway. Other interesting transformations include the formation of flavonoids through an ortho-quinone methide (o-QM) cycloaddition-oxidation sequence and regioselective β-glycosidations of several unprotected flavanones suggesting a likely synthesis of 2 from the aglycone 33. 相似文献
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Methods for synthesis of two crucial intermediate A and B starting with 2,4,4-trimethyl-2-cyclo-hexenone 1 and 2,3-dibromofuran 9 are disclosed. 相似文献
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