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《Tetrahedron letters》1986,27(34):3963-3966
Regioselective metallation and alkylation/acylation of 2-aryl-1,3-dioxanes was achieved in high yield. 相似文献
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Comparative conformational analysis of 2,2-dimethyl- and 2,2,5-trimethyl-1,3-dioxanes as well as their 2-heteroanalogs with silicon and germanium atoms has been performed by means of computer simulation using HF/pVDZ, hybrid DFT PBE/3ξ, and RI-MP2/λ2 methods. The potential energy surface for all the studied compounds has revealed the presence of the chair and 2,5-twist conformers. The latter form, in the case of substituted 1,3-dioxa-2-silacyclohexanes at the HF/pVDZ level, is a transition state rather than an intermediate minimum. The molecules of 2-sila- and 2-germa-1,3-dioxacyclohexanes exhibit an enhanced conformational flexibility as compared to the 1,3-dioxanes. 相似文献
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A new synthesis of chlorine-substituted 1,3-dioxanes is effected from methylallyl chloride and isocrotyl chloride by condensing them with paraformaldehyde in the presence of KU-2 cation-exchange resin. 相似文献
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2-Phenylethynyl substituted 1,3-dioxanes were obtained by the reaction of 1,3-dioxanium salts with an lotsich reagent. It was shown that they are readily hydrolyzed with the formation of a-acerylenic ketones. A simple new method is proposed for the synthesis of the latter without isolating the intermediate 1,3-dioxanes using the reaction of 4 substituted 2-methyl(phenyl, furyl)-1,3-dioxanium salts with hydroxymethyl- and phenylethynylmagnesium bromide as examples.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 193–197, February, 1996. 相似文献
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Several methods for the preparation of 2-perfluoromethyl-substituted 1,3-dioxolanes and 1,3-dioxanes were tried. The method of Nerdel for the preparation of 1,3-dioxolanes, making use of the condensation between carbonyl compounds and oxiranes, was found to be suitable for perhalogenated ketones and aldehydes, and may even be extended to oxetanes, affording 2-perhaloalkylated 1,3-dioxanes.The yield of the cyclic acetals drops with inreasing substitution. 相似文献
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T. P. Kosulina V. G. Kul'nevich E. N. Moskalenko M. A. Khusainov Z. A. Starikova E. A. Kantor 《Chemistry of Heterocyclic Compounds》1998,34(4):431-437
Reaction of 2,4,4,6-tetramethyl-1,3-dioxanium perchlorate with lotsich reagents led to the synthesis of new silylethynyl-substituted 2,4,4,6-tetramethyl-1,3-dioxanes. According to the data of1H and13C NMR and x-ray diffraction analysis, it was established that the 1,3-dioxane ring of the products obtained has the chair conformation.Kuban' State Technological University, Krasnodar 350072, Russia. Ufa State Oil Technical University, Ufa 450062, Russia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 487–493, April, 1998. 相似文献
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The rate constants for the reaction between chlorine atoms and either 5-methyl-2-hexanol, 2,2-dimethyl-3-hexanol, or 2,4,4-trimethyl-1-pentanol at 298 K were determined using the relative method with 2-butanol and 1-pentanol as reference compounds. The values obtained for 5-methyl-2-hexanol, 2,2-dimethyl-3-hexanol, and 2,4,4-trimethyl-1-pentanol (k × 1010 cm3 molec−1 s−1) were, respectively, (2.64 ± 0.5), (2.72 ± 0.5), and (2.50 ± 0.4), in agreement with the values of the rate constants reported in bibliography for similar alcohols and the values estimated by structure activity relationship methods. The photooxidation products of 2,4,4-trimethyl-1-pentanol initiated by chlorine atoms were identified (formaldehyde, 2-propanone, 2,2-dimethyl propanal, 4,4,-dimethyl-2-pentanone, and 3,3-dimethylbutanal), and the reaction mechanism was determined. 相似文献
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E. T. Lesnikova S. S. Zlotskii D. L. Rakhmankulov 《Chemistry of Heterocyclic Compounds》1991,27(1):30-32
Cyclic acetals containing alkenyl groups were obtained from 5-methyl-5-acyl-1,3-dioxane. The 1,3-dioxane fragment does not interfere in reduction of the carbonyl group, nor in participation of the carbonyl group in Wittig and Grignard reactions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 37–39, January, 1991. 相似文献
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Yanilkin V. V. Bredikhina Z. A. Maksimyuk N. I. Morozov V. I. Nastapova N. V. Bredikhin A. A. 《Russian Chemical Bulletin》2002,51(1):78-84
The character of the first stage of reduction of 5-X-5-nitro-1,3-dioxanes 1—10 and 2-X-2-nitro-1,3-propanediols 11 and 12 is independent of the nature of halogen (X = Br, Cl) and substituents in position 2 of the dioxane cycle. The transfer of two electrons to a molecule of compound 1—12 is accompanied by the anionoid elimination of halogen and formation of the anion of nitronic acid. The high mobility of halogen is mainly due to the acceptor nitro group capable of further transformations in the -position to halogen. The direction of further reduction involving the electron transfer to electrochemically active groups in the aromatic fragment of the molecule is determined by the nature of these groups. Chloro-, bromo-, and iodophenyl-substituted derivatives 4, 5, and 8—10 are reduced as typical halobenzenes. In the case of nitrophenyl-substituted compounds 3 and 7, the dioxane cycle opens to form dianions of p- and m-nitrobenzaldehydes along with the reduction of the nitroso group through the stages of formation of the radical anion and radical anion of the nitroso group. The radical anions of the nitro and nitroso derivatives were identified by ESR. 相似文献
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L. F. Lapuka O. B. Chalova E. A. Kantor T. K. Kiladze D. L. Rakhmankulov 《Chemistry of Heterocyclic Compounds》1981,17(9):876-879
It was established by PMR spectroscopy that a chair conformation with an axial orientation of the alkoxy substituent is the primary conformation for 5,5-disubstituted (and unsubstituted) 2-alkoxy-1,3-dioxanes. As compared with alkyl-1,3-dioxanes, 2-alkoxy-1,3-dioxanes are characterized by reversal of the chemical shifts of the axial and equatorial protons attached to C4, and C6.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1182–1185, September, 1981. 相似文献