The intramolecular cycloalkylation of isomeric 2-methyl-4-phenyl-2-butanol and 3-methyl-3-phenyl-1-butanol in D{sub 3}PO{sub 4} is accompanied by hydrogen exchange with the formation of deuterated 1,1-dimethylindane. The distribution of the deuterium in the polymethylene ring shows that the reaction of the first alcohol takes place as a result of C{sub 5}-cyclization of the {gamma}-phenylalkyl cation, whereas the reaction of the second alcohol takes place by direct C{sub 5}-cyclization and by cyclization of the {gamma}-phenylalkyl cations formed as a result of 1,2- and 1,3-transfers of the phenyl group.
On the basis of the electron-impact mass spectra of a series of 1-diazo-4-methoxycarbonyl-2-butanones, the data from high-solution mass spectrometry, and the spectrum of the deuterated analog it was shown that the (M-N{sub 2}){sup +{center dot}} ions formed at the first stage in the fragmentation of the molecular ions of these compounds are partly stabilized with the formation of pseudomolecular ions of oxolanones. The molecular ions of the diazo ketones themselves can dissociate in various directions. The many-path dissociation makes it possible to suppose that the yield of oxolanones formed during cyclization in solution under the influence of acidic agents is small.
It was established by NMR spectroscopy ({sup 1}H and {sup 13}C) that 3-allyl-1,2,3-trimethyl-4-methylenecyclobutene is protonated in the acid system HSO{sub 3}F-SO{sub 2}FCl with the formation of the 4-allyl-1,2,3,4-tetramethylcyclobutenyl cation, which rearranges to the 1,2,3,4-tetramethylbicyclo(4.1.0)hept-2,3,4-enyl cation ({Delta}G{sub {minus}90{degree}C}{sup ne} {approximately} 54 kJ/mole). By means of labeled atoms (a deuterium label) data were obtained in favor of a two-stage mechanism of rearrangement with the intermediate formation of the 1,5,6,7-tetramethylbicyclo(3.2.0)hept-6-en-3-yl cation, where the controlling stage is the first stage, i.e., the carbocationic cyclization stage. A similar transformation is observed during the action of 95% sulfuric acid or the acid system HCl-AlCl{sub 3} in methylene chloride on 3-allyl-1,2,3-trimethyl-4-methylene-cyclobutene.
In a continuation of researches into the sulfonate activation of electrophilic reagents the authors have studied the reaction of sulfur trioxide with (phenyliodonio)dimethyloxycarbonylmethanide (I). This reaction takes place exothermically when equimolar amounts of the ylide (I) and sulfur trioxide are mixed in anhydrous methylene chloride at {minus}78{degree}C. It gives a quantitative yield of ((bis-methoxycarbonyl)) phenyliodoniomethanesulfonate (II). Compound (II) is unstable at room temperature and decomposes after a few hours with the formation of iodobenzene and diathene. The products from decomposition of the reagent (II), including tetramethoxycarbonylethene and the dithiane, were formed in the reactions of (II) with olefins, and iodobenzene was realized. The authors have obtained for the first time a relatively stable adduct of an iodonium ylide with such a Lewis acid as sulfur trioxide.
A 1:3400 mixture of 2-/sup 14/C-labelled methyl bromoacetate with the nonradioactive ester gave labelled dimethoxy-2-oxo-3-(m-chlorophenoxy)phosphonate which was used for the synthesis of 16-/sup 14/C-labelled cloprostenol by the Corey strategy. The radioactivity was measured using an Izokap-300 scintillation counter. The IR spectra were taken neat on a UR-20 spectrophotometer. The PMR spectra were taken on a Tesla-480-B spectrometer with TMS as the internal standard. The /sup 13/C NMR spectra were taken on a JEOL-90Q spectrometer at 22.50 MHz in CDCl/sub 3/ with TMS as the internal standard. The ratio of the isomers at C/sup 15/ was determined by a DuPont 8800 high-pressure liquid chromatograph.
Aromatic thiols and 2-thiophenethiol react with ..beta..-chloro- and ..beta..-bromostyrene when heated to form the corresponding 1-phenyl-2-aryl(thienyl)thioethenes. The reaction begins at 80/sup 0/C and takes place effectively and strictly stereospecifically at 140-160/sup 0/C. The yield of the respective vinyl sulfides amounts to 70-95%. ..beta..-Bromostyrene reacts with thiophenol more slowly than ..beta..-chlorostyrene, and this is due to the inhibiting action of the hydrogen bromide, which acts as a trap for the thiyl radicals and gives rise to decomposition of the obtained 1-phenyl-2-phenylthioethene. Among the investigated thiols 2-thiophenethiol has the lowest reactivity.
ChemInformVolume 18, Issue 38 Natural Products ChemInform Abstract: Synthesis of 22S,23S-Brassinosteroids from Stigmasterol. A. A. AKHREM, A. A. AKHREM Inst. bioorg. khim. Akad. nauk BSSR MinskSearch for more papers by this authorF. A. LAKHVICH, F. A. LAKHVICH Inst. bioorg. khim. Akad. nauk BSSR MinskSearch for more papers by this authorV. A. KHRIPACH, V. A. KHRIPACH Inst. bioorg. khim. Akad. nauk BSSR MinskSearch for more papers by this authorN. V. KOVGANKO, N. V. KOVGANKO Inst. bioorg. khim. Akad. nauk BSSR MinskSearch for more papers by this authorV. N. ZHABINSKII, V. N. ZHABINSKII Inst. bioorg. khim. Akad. nauk BSSR MinskSearch for more papers by this author A. A. AKHREM, A. A. AKHREM Inst. bioorg. khim. Akad. nauk BSSR MinskSearch for more papers by this authorF. A. LAKHVICH, F. A. LAKHVICH Inst. bioorg. khim. Akad. nauk BSSR MinskSearch for more papers by this authorV. A. KHRIPACH, V. A. KHRIPACH Inst. bioorg. khim. Akad. nauk BSSR MinskSearch for more papers by this authorN. V. KOVGANKO, N. V. KOVGANKO Inst. bioorg. khim. Akad. nauk BSSR MinskSearch for more papers by this authorV. N. ZHABINSKII, V. N. ZHABINSKII Inst. bioorg. khim. Akad. nauk BSSR MinskSearch for more papers by this author First published: September 22, 1987 https://doi.org/10.1002/chin.198738318Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume18, Issue38September 22, 1987 RelatedInformation
In most cases the alkylation of the sodium derivatives of 1-phenyl-1-alkyl-2-alkynes by methyl, ethyl, isopropyl, and tert-butyl bromides in liquid ammonia takes place preferentially at the sp/sup 2/-hybridized carbon atom, and this leads to the formation of the corresponding acetylenes, The regioselectivity of the reaction is explained by the greater softness of the trigonal atom of the ambient propargyl anion and its smaller screening by the solvate shell compared with the diagonal atom.
The kinetics of the reaction of 5-phenyltetrazole triethylammonium salt with methyl vinyl ketone in acetonitrile and DMFA were studied. At a concentration of approx. 2.5 x 10/sup -1/ M the 5-phenyltetrazole triethylammonium salt is associated, and an intimate ion pair, formed with participation of a hydrogen bond, enters into reaction with the methyl vinyl ketone. The controlling stage is the formation of the anionic intermediate, the subsequent protonation of which leads to the final reaction products. The PMR spectra were recorded on a Perkin-Elmer R-12 spectrometer at 60 MHz in acetone-d/sub 6/ with HMDS as internal standard.
Significant differences were found in the reactivity of a series of epoxides of cycloalkenes and methylenecycloalkanes and diepoxides in reaction with triphenylphosphine, depending both on the steric effects of the cyclic fragments and on their strain. The level of the strain can be judged indirectly from the chemical shifts of the /sup 1/H and /sup 13/C nuclei and the spin-spin coupling constants of the C-H bonds in the epoxide ring.
AbstractThe reactions between cis‐dichloroethene (I), its trans isomer (VII) or a mixture of these and phenylselenol (II) under the conditions of phase‐transfer catalysis afford the cis‐1‐phenylseleno‐2‐chloroethene (III) as the main product along with its trans isomer (IV), 1‐phenylseleno‐1‐chloroethene (V) and benzyl phenyl selenide (VI).
A new modification of the steroid skeleton of the solasodine aglycone was realized; compounds of the A-nor-3-azaspirosolane series with an unsubstituted position 28 were obtained. The properties of the synthesized heterocyclic analogs of solasodine were studied.
It was shown by PMR spectroscopy that acetylpinacolin acylhydrazones exist in deuterochloroform and deuterodimethyl sulfoxide solutions as mixtures of the hydrazone, enehydrazine, and cyclic 5-hydroxypyrazoline forms. In the series of acetylpinacolin aroylhydrazones the introduction of electron-withdrawing substituents into the aromatic ring of the N-aroyl radical shifts the ring-chain tautomeric equilibrium toward the 5-hydroxypyrazoline form. In the series of products from the condensation of acetylpinacolin with the hydrazides of aliphatic acids the proportion of the open-chain tautomer increases with increase in the size of substituent in the N-acyl part.
Thiazolidinethiones were investigated by the PMR method in order to compare the magnetically anisotropic characteristics of the acetylene and ethylene bonds and to study their conformation. A conformation with an intramolecular hydrogen bond, including the sulfur atom and the proton of the hydroxyl group, is proposed on the basis of an analysis of the factors affecting the chemical nonequivalence of the geminal methyl groups at the ..cap alpha.. position to the asymmetric carbon atom. The conformation clearly explains the characteristics of the PMR spectra of the thiazolidinethiones.
11-Deoxy-13,14-dihydro-13-thia-16-aryloxy-17,18,19,20-tetranorprostaglandin-E/sub 1/ and their diastereomers were synthesized by the conjugate 1,4-addition of 2-hydroxy-3-aryloxypropanethiols to 2-(6-ethoxycarbonylhexyl)-2-cyclopenten-1-one.
