1,4-Dioxanes as products of the oxidation of N-vinyllactams

2, 5-Disubstituted 1,4-dioxanes have been obtained by the oxidation of N-vinyllactams, represented by N-vinylpyrrolidone, N-vinylpiperidone, and N-vinylcaprolactam, and their structure has been shown by independent synthesis: the reaction of trans-2, 5-dichloro-1,4-dioxanes with alkali-metal salts of the lactams also gave 2,5-di(N-2-oxopolymethyleneimino)-1,4-dioxanes.     

Heterocyclization of Allyloxyiodination Products of Halogen-Substituted Styrenes

Russian Journal of Organic Chemistry - A procedure has been proposed for the synthesis of 2-aryl-5-methyl-1,4-dioxanes by alkoxyiodination of halogen-substituted styrenes with allyl alcohol in the...     

Reaction of glyceraldehyde with aryl and alkyl chloroformates

A number of 2,5-bis(aryl- and alkyloxycarbonyloxymethylene)-3,6-bis(aryl- and alkoxycarbonyloxy)-1,4-dioxanes 5a-d have been prepared by the reaction of glyceraldehyde with aryl and alkyl chloroformates. Bis aryl carbonates were also formed under certain conditions in this reaction. Nuclear magnetic resonance analysis of 5c indicated that it existed in a chair conformation with all the substituents in an equatorial position.     

Rh2(OAc)4-catalyzed reaction of 1,3-dioxanes with methyl diazoacetate

The reactions of methyl diazoacetate with 1,3-dioxanes in the presence of Rh₂(OAc)₄ afford 1,4-dioxepanes in up to 46% yields. The insertion of methoxycarbonylcarbene into the C—O bond occurs only in the case of 2-phenyl-1,3-dioxanes.     

Some properties of 2-alkoxy-1-alken-3-ols

Conclusions The reaction of 2-alkoxyacroleins with Grignard reagent gave some new 2-alkoxy-1-alken-3-ols, which in the presence of p-toluenesulfonic acid are cyclodimerized to 2,3,5,6-tetraalkyl-2,5-dialkoxy-1,4-dioxanes, which tend to cleave ethanol to give 2,3,5,6-tetraalkyl-5-alkoxy-1,4-dioxenes.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2534–2538, November, 1980.The authors express their gratitude to V. I. Lavrent'ev and V. Yu. Vitkovskii for taking the mass spectra.     

Homolytic amination of benzo-1,4-dioxane

When 5,6-benzo-1,4-dioxane was reacted with N,N-dialkylchloramines in the presence of FeSO₄ at 10–20C in a solution of acetic and sulfuric acids, 6-(N,N-dialkylamino)benzo-1,4-dioxanes and 6-chloro- and 6,7-dichloro-benzo-1,4-dioxanes were obtained. Under the conditions used in the study mainly chlorination products were synthesized. Reaction of 5,6-benzo-1,4-dipxane with the system (NH₃OH)₂SO₄-TiCl₃ resulted in the formation of 6-aminobenzo-1,4-dioxane.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 316–318, March, 1989.     

Radical telomerization of 1-hexene by 1,4-dioxane

It was established that telomer homologs of a number of 2-alkyl-1,4-dioxanes are formed as a result of radical telomerization of 1-hexene by 1,4-dioxane. The partial chain-propagation constants of the process were calculated, and the mass spectra of the reaction products were studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1192–1194, September, 1983.     

Alkoxy compounds

Twenty-six previously unreported 5-alkoxymethyl-2,5-dialkyl-1,3-dioxanes have been synthesized by the condensation of 2-alkoxymethyl-2-alkylpropane-1,3-diols with aldehydes. It has been shown by an analysis of the PMR spectra of these dioxanes that the 1,3-dioxanes considered are mixtures of two stereoisomers. In some cases these mixtures have been resolved into the individual isomers by vacuum fractionation in efficient columns. The configurations and conformations of the stereoisomeric 5-alkoxymethyl-2,5-dialkyl-1,3-dioxanes have been established by the NMR method; it has been shown that the lower-boiling isomers have the trans configuration and predominantly the chair conformation and the higherboiling isomers the cis configuration and predominantly an unsymmetrical boat conformation.For part XX, see [7].     

Alkoxy compounds

The reduction of alkoxymethylalkylmalonic esters with lithium aluminum hydride has given previously unknown 2-alkyl-2-alkoxymethyl-1, 3-propanediols, and by the condensation of these with ketones six previously unreported 2, 2, 5-trialkyl-5-alkoxymethyl-1, 3-dioxanes have been synthesized. The PMR spectra of these compounds have been studied and the unsymmetrical boat conformation has been shown for the 2, 2, 5-trialkyl-5-alkoxymethyl-1, 3-dioxanes. The causes of the stereochemical features of the compounds mentioned are discussed.For part XXII, see [5].     

Synthesis of 2-substituted 1,4-dioxanes from 1,2-epoxy-3-(2-chloroethoxy)propane

A number of 2-substituted 1,4-dioxanes were synthesized from -chloroethyl glycidyl ether, the appropriate alcohols, and diethylamine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 161–163, February, 1973.     

Polyfluorocycloalkenes Part XIII [1]. Reactions of perfluorocycloalkenes with 1-ethoxy-1-(2-hydroxyethoxy) ethane in the presence of base

1-Ethoxy-1-(2-hydroxyethoxy) ethane and sodium hydride with octafluorocyclopentene, decafluorocyclohexene and dodecafluorocycloheptene produced acid-labile acetals which were hydrolysed to the corresponding 1-(2-hydroxyethoxy) perfluorocycloalkenes. Cyclisation of these compounds under basic conditions gave substituted dioxolans and not 1,4-dioxanes.     

Synthesis of mono- and bis(aminomethyl)dioxanes fromN-[3-(2-chloroethoxy)-2-hydroxypropyl]sulfamates

N-Substituted aminomethyl- and 2,5-bis(aminomethyl)-1,4-dioxanes were prepared by cyclization of the corresponding potassiumN-[3-(2-chloroethoxy)-2-hydroxypropyl]sulfamates under the action of an alkaline agent followed by alcoholysis of the resulting sulfamic acids.     

Alkoxy compounds

Six 2, 2, 5-trialkyl-5-α-alkoxyethyl-1, 3-dioxanes have been synthesized for the first time by the condensation of 2-alkyl-2-α-alkoxyethyl-1, 3-propane diols with ketones, and it has been shown by a study of their PMR spectra that they exist in the unsymmetrical boat conformation. The PMR spectra of a number of previously-synthesized 2-alkyl(aryl)-5-alkyl-5-α-alkoxyethyl-1, 3-dioxanes have been considered and it has been shown that from an analysis of the spectra it is possible to estimate the contents of geometrical isomers in a mixture. The stereochemistry of these compounds has been discussed.     

From 1,2-dialkoxyalkanes to 1,4-dioxanes. A transformation mediated by NbCl(5)via multiple C-O bond cleavage at room temperature

The formation of 1,4-dioxanes and alkyl chlorides from the reactions of polyethers (dme, diglyme, 1,2-diethoxyethane, 1,2-dimethoxypropane) with NbCl(5) at room temperature is described; as far as dme is concerned, the reaction mainly occurs in two steps, consisting of (i) cleavage of one O-CH(3) bond, followed by (ii) cleavage of the second O-CH(3) bond and one of the two O-CH(2) linkages. The characterization of intermediate complexes and the isolation of NbOCl(3)(dme) are reported.     

Solvent effects in NMR spectra induced by aromatic solvents in 1,4-dioxanes, 1,3-dioxolanes and in sulphur analogues

NMR solvent effects induced by aromatic solvents on some 1,4-dioxanes, 1,3-dioxolanes and on some sulphur analogue derivatives are reported. The shielding effect of the aromatic solvents is examined in respect to the structure of the solute.     

Electrophilic substitution of 5- and 6-substituted benzo-1,4-dioxanes

The compositions of the products of bromination, nitration, and acetylation of 5- and 6-fluoro(chloro, nitro, methoxy, methyl, formyl, and carboxy)benzo-1,4-dioxanes were established. The reactivity indexes and the characteristics of the UV spectra of the starting compounds were calculated by the self-consistent-field (SCF) MO LCAO method within the Pariser-Parr-Pople (PPP) and CNDO/2 CI (complete neglect of differential overlap with configuration interaction) approximations, and the results were compared with the experimental data.Translated from Khimiya Geterotsiklicheskikh Soedinenii,No. 11, pp. 1465–1471, November, 1978.     

Highly effective stereoselective synthesis of vinyl ethers of 5-alkyl-2-(2-furyl)-5-hydroxymethyl-1,3-dioxanes

The vinylation of cis-5-alkyl-5-hydroxymethyl-2-(2-furyl)-1,3-dioxanes in the KOH–DMSO system in acetylene at atmospheric or elevated pressures (85-100°C, 3 h) takes place stereoselectively and leads to the formation of cis-5-alkyl-2-(2-furyl)-5-vinyloxymethyl-1,3-dioxanes with yields of up to 93%.     

Research on furan acetal compounds

The configuration and preferred conformations of a number of stereoisomeric 2-(α-furyl) 1,3-dioxanes were established by PMR spectroscopy. It is shown that cis orientation of the NO₂ groups with respect to the furyl ring is primarily realized for 2-(α'-nitro-α-furyl)-5-ethyl-5-nitro-1,3-dioxanes.     

Steerochemistry of heterocycles.

The stereochemical peculiarities of substituted 1,3-dioxanes and 1,3-dithianes are discussed. The high probability of the existence of flexible conformations in these series, the considerable energy preference of the 5-C-axial position in the chair conformation of 1,3-dioxanes and 1,3-dithianes, and the definite preference of the 2-C-axial position in the chair conformation of 1,3-dithianes as compared with the axial conformations of the cyclohexane type are noted. The PMR spectra of stereoisomeric 2,5-dimethyl-5-isopropyl-1,3-dioxanes, 2-methy-l5-isopropyl-1,3-dithianes, and 2,2,5-trimethyl-1,3-dithiane are described, and their configurations and preferred conformations are proved. The results of a study of the epimerization of stereoisomers of substituted 1,3-dioxanes and 1,3-dithianes are examined, and the conformational energies of individual substituents in the 5-position of these cyclic systems are calculated on the basis of this examination.See [48] for communication IV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 582–592, May, 1971.     

Conformational analysis of trans-2,3-diaryloxy-1,4-dioxanes. A tool for discriminating between steric and electronic effects in the position of

The conformation of several $\text{trans}$-2,3-diaryloxy-1,4-dioxanes has been studied using ¹H NMR techniques. $\text{Trans}$-2,3-bis(4-nitrophenoxy)-1,4-dioxane and $\text{trans}$-2,3-bis(4-methoxyphenoxy)-1,4-dioxane have been found to be predominantly ( ≈98%) in diaxial conformation in CDCl₃). On the other hand, $\text{trans}$-2,3-bis(2,6-dimethylphenoxy)-1,4-dioxane exists in the same conditions as a 66:33 mixture of diaxial and diequatorial conformers. An explanation based on the fulfilment of the exo-anomeric effect is provided.