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Alkyl-substituted oxiranes

A review of the IR frequencies of the three-membered heterocycles is found in Katritzky and Ambler. The IR frequencies were more recently studied by Potts. " George recorded the IR spectra of 16 straight-chain oxiranes for analytical purposes and reported their refractive indices too. IR (4000-200cm" ) and Raman spectra have been taken in the solid and the liquid phases for the conformational examination of alkyl-substituted oxiranes. Studies have been made of the steric structure of oxirane-carboxaldehydes and the low-temperature oxidation of cyclohexene in the presence of Co" chelates. Analyses have been carried out on the IR spectra of oxiranes in the region of 850 cm" and the vibrational energy levels. Steroid oxiranes have likewise been subjected to IR investigation. Hirose published the rotational spectra of 10 oxiranes together with their evaluation and, in conjunction with the microwave spectra, determined thero,r, andr, structures of the compounds. [Pg.9]

Oxiranes can be converted to dialdehydes with hydrogen peroxide in the presence of a boric acid ester or phosphoric acid ester.The base-catalyzed oxidation of oxirane and alkyl-substituted oxiranes with fcA-r-butylhydroperoxide has been reported. With increased substitution the molecule undergoes fragmentation. With DMSO in the presence of terf-butylhydroperoxide and strong acids, a-ketols are formed via a sulfonium salt (Eq. 156). ... [Pg.77]

By variation of the solvent, not only alkyl-substituted oxiranes but also a,P-unsaturated alcohols can be obtained from halooxiranes (Eq. 281). ... [Pg.111]

Carbon-13 shift values of parent heterocycloalkanes [408] collected in Table 4.61 are essentally determined by the heteroatom electronegativity, in analogy to the behavior of open-chain ethers, acetals, thioethers, thioacetals, secondary and tertiary amines. Similarly to cyclopropanes, three-membered heterocycloalkanes (oxirane, thiirane, and azirane derivatives) display outstandingly small carbon-13 shift values due to their particular bonding state. Empirical increment systems based on eq. (4.1) permit shift predictions of alkyl- and phenyl-substituted oxiranes [409] and of methyl-substituted tetrahydropyrans, tetrahydrothiapyrans, piperidines, 1,3-dithianes, and 1,3-oxathianes [408], respectively. Methyl increments of these heterocycloalkanes are closely related to those derived for cyclohexane (Table 4.7) due to common structural features of six-membered rings. [Pg.272]

Hydration of aryl-substituted epoxides. Treatment of aryl-substituted oxiranes with copper(II) sulfate and pyridine in an aqueous phosphate buffer (pH 7) affords cis-diols by reaction of water at the benzylic position. Less than 15% of trans cleavage products obtain. In the absence of pyridine, the oxides are rapidly destroyed. Triethylamine cannot be substituted for pyridine. cis-Chlorohydrins are obtained when aryl-substituted oxides are treated with copper(II) sulfate, pyridine, and kiCl in THF, When methanol is used as solvent, the corresponding cis-glycol monomethyl ether is obtained. In all cases substitution occurs at the benzylic position. Alkyl oxiranes do not react under these conditions. ... [Pg.369]

The differences between the IR and Raman spectra were examined as long ago as the 1930s. Mousseron later performed measurements on many oxiranes and identified the individual vibration bands. More recently, the results of solid-, liquid-, and gas-phase studies on the Raman spectra of alkyl- and vinyl- substituted oxiranes have been reviewed. [Pg.13]

A fair number of publications have appeared on the isomerization of alkyl- and aryl-substituted oxiranes also containing other functional groups (e.g. Refs. " ). [Pg.66]

With asymmetrically substituted oxiranes the alkyl group is incorporated here on the more easily approachable side. The action of phenyllithium on chlorooxiranes has been examined. Depending on the structure of the oxirane, the transformations found in Eqs. 278-280 take place these could be of value for preparative purposes. [Pg.110]

The effect of a heteroatom 0 to the oxirane ring has been studied in the reaction of monosubstituted oxiranes 131 and benzylamine. If X = 0, the reaction occurs via the transition state 132 with neighbouring-group participation. Neighboring-group participation has similarly been observed in the reactions of mono- and tri-substituted oxiranes and )3-substituted primary amines. The product ratio of the aminoalcohols formed from the reactions of a-vinyloxiranes and primary amines depends on the geometry of the oxirane.Base-catalyzed addition of oxiranes to oximes leads not only to 0-alkyl but to A -alkyl derivatives (Eq, 319). ... [Pg.124]

Cyclohexene oxide and its 3-hydroxy derivatives have been opened regio- and stereospecifically with phosphodiesters. The mechanism of the reaction of oxiranes with sodium dialkyl phosphite and diphenylphosphines has been studied. Cyclopropanecarboxylic acid derivatives have been obtained from substituted oxiranes with triethylphosphonoacetate anion.The mechanism of formation of isomeric alkoxyalkylacetates from oxiranes with alkyl halides and mercuric acetate has been discussed. ... [Pg.125]

Mechanistic studies have been reported on the addition of alkylphosphonic acid reagents (325) to trialkyl-substituted epoxides (326). The addition occurs according to a three-step mechanism starting with rapid nucleophilic attack of the phosphorylated anion on the most alkyl-substituted carbon of oxirane, followed by formation of a dioxaphospholane structure (327) with release of... [Pg.164]

The Li—F chelation-enabled stereoselective generation of cis-2-lithio-3-CF3-oxiranes (70) leads to the preparation of CF3 -substituted tetra-substituted oxiranes (67) in a stereoselective manner. The Li—F chelation controlled a stereospecific S -type replacement of chlorine with alkyl group via 68, followed by stereospecific oxirane-ring formation via 69, resulting in the formation of 67 in excellent diastereomeric excess (Scheme 3.14) [29]. [Pg.147]

In media with increased acidity and alkyl substitution of double bonds of the initial unsaturated oligomers, isomerizations of epoxy cycles in ketonic or aldehydic groups may occur. Acid media and high temperatures enhance oligomerizations of oxiranic cycles, with the formation of etheric bonds. [Pg.206]


See other pages where Alkyl-substituted oxiranes is mentioned: [Pg.577]    [Pg.220]    [Pg.220]    [Pg.167]    [Pg.167]    [Pg.271]    [Pg.117]    [Pg.121]    [Pg.126]    [Pg.115]    [Pg.577]    [Pg.220]    [Pg.220]    [Pg.167]    [Pg.167]    [Pg.271]    [Pg.117]    [Pg.121]    [Pg.126]    [Pg.115]    [Pg.286]    [Pg.159]    [Pg.563]    [Pg.208]    [Pg.194]    [Pg.204]    [Pg.310]    [Pg.311]    [Pg.62]    [Pg.128]    [Pg.165]    [Pg.88]    [Pg.110]    [Pg.112]    [Pg.178]    [Pg.215]    [Pg.178]    [Pg.598]    [Pg.424]    [Pg.424]    [Pg.40]    [Pg.185]    [Pg.420]    [Pg.83]    [Pg.424]    [Pg.199]   
See also in sourсe #XX -- [ Pg.9 ]




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Alkyl substitute

Oxiranes substituted

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