The structure of adducts of benzaldoxime and m-chlorobenzaldoxime dehydrodimers with styrene

The reaction of m-chlorobenzaldoxime dehydrodimer with styrene gives two 1:1 adducts.The main product 7 is a bisnitrone. The minor product 8 has been shown by X-ray diffraction anal-ysis to possess the structure: ArCH(N=O)CH_2CH (Ph)O--N=CHAr. The two C=N bonds areall in Z configuration. The structure of the adducts from benzaldoxime dehydrodimer and styrene isalso assigned.     

The STO-3G transition structure of the diels-alder reaction

A transition structure with C_S symmetry for the Diels-Alder reaction of butadiene with ethylene has been obtained with the STO-3G basis set. Stereochemical consequences are discussed.     

Separate deamination mechanisms for isomeric styrene oxide induced N1-adenine adducts

[formula: see text] Styrene 7,8-oxide (SO) induced N1-2'-deoxyadenosine 5'-phosphate (AMP) adducts deaminate to corresponding inosine derivatives. For the beta-isomer of N1-SO-AMP, the chiral alpha-carbon was found to be involved in the hydrolytic deamination, suggesting formation of an oxazolinium ring as an intermediate and that a water molecule attacks the benzylic carbon. The mechanism differs from the one suggested for the alpha-isomer of N1-SO-AMP, for which deamination occurs by direct attack of water at the 6-position of purine ring.     

The synthesis of four isomeric bisthienothiepinones

The displacement reaction between sodium thiophene-3-thiolate and methyl 3-(bromomethyl)thiophene-2-carboxylate ( 5 ) gave the expected thioether 7a . Basic hydrolysis afforded the carboxylic acid 7b ; conversion to the acid chloride, and treatment of the latter with stannic chloride then produced the bisthienothiepinone 1 . Using analogous reactions the isomers 2-4 were also synthesized.     

Cope rearrangements of diels-alder adducts containing norbornene and norbornenone systems

The product formed from cyclopentadiene and the cyclo-octatetraene dimer 5a has been shown to possess structure 6a, probably resulting from Cope rearrangement of an initial adduct 4a. The reaction of tetraphenylcyclopentadienone with 1 - methoxybuta - 1,3 - diene yields a mixture of the exo-adduct 14 and the rearranged endo-adduct 13 Rearrangement of the norbornenone derivative 27 gives the Cope product 29 Treatment of the 4,5-fused 2,3,4,5-tetrachlorocyclopent-2-enones 29,40 and 41 with powdered sodium hydroxide in tetrahydrofuran results in ring-cleaveage with the formation of 2,3,5-trichlorobuta-2,4-dienoic acid derivatives, 36, 43 and 44 respectively.     

Mass spectrometry of isomeric methyl phenylpentanoates and methyl phenylnonanoates

The mass spectra of methyl 3-, 4- and 5-phenyl pentanoates, and all the straight-chain methyl phenylnonanoates have been recorded. The major fragmentation patterns have been discussed; when the phenyl group is non-terminal, cleavage was observed at the branching position. It is shown that a mixture of methyl 3-, 4- and 5-phenylpentanoates may be analysed both qualitatively and quantitatively by mass spectrometry; in a methyl phenylnonanoate mixture a similar analysis is possible with the exception of the 8- and 9-phenyl isomers.     

Salt-catalyzed reaction between styrene oxide and silk fibroin

The addition reaction of styrene oxide (StO) with silk fibroin was studied in the presence of various salts in different solvents at 45–75°C. Some water was required to make StO react with silk padded with various salt solutions. The reaction rate increased with the salt concentration and reached a maximum value at a certain concentration of the salt. Padding with solutions of thiosulfate, cyanide, thiocyanate, bicarbonate, or carbonate resulted in high add-ons (to 65 mole/10⁵ g) and low solubilities in HCl and NaOH aqueous solutions. The weight gains increased with the epoxide concentration and reached a constant value at a certain concentration of StO solution in ethanol, while they decreased slightly with epoxide concentration over 10% of StO solution in n-hexane. Histidine, lysine, arginine, tyrosine, and aspartic and glutamic acids were found to react. The reaction rate decreased with increasing solubility parameter of the solvent used, reached a minimum value about at 10 or at the solubility parameter of the epoxide, and then increased with the parameter. The StO–silk reaction may depend on the distribution of StO between aqueous salt and an organic solvent phases, and on the swelling of silk fiber in different aqueous salt solutions or in various organic solvents. The mechanism for this epoxide-silk reaction and the reactivity difference between StO and phenyl glycidyl ether toward silk fibroin are discussed in the light of the observed phenomena.     

Properties and cage lactone synthesis of diels-alder adducts from 2-pyrones

New cage lactones were synthesized by the photocyclization of the tricyclodienolactones 1a, 1b, 2 which were available from the Diels-Alder reactions of 2-pyrones with p-benzoquinones or norbornadiene. Retro-Diels-Alder reactions of cross-adducts between 2-pyrone-mono-adducts and p-benzoquinone were also described.     

Intramolecular diels-alder reaction of iminothiol esters

Diels-Alder reaction of dienyl α-methacrylthioimidates has been investigated under thermal or Lewis acid or protonic acid catalysed conditions. The utility of the reaction is shown by desulfurative ring contraction of bicyclo[4.4.0] to bicyclo[4.3.0]system.     

The reaction of cyclones with isomeric dihydronaphthalenes

Summary In the reaction of cyclones with isomeric dihydronaphthalenes there is reduction of the cyclones to dihydro-cyclones because of dehydrogenation of the dihydronaphthalenes.     

The structure of isomeric anthraquinonesulfonic acids

The ultraviolet and infrared spectra of the isomeric anthraquinonesulfonic acids in the solid state and in aqueous and sulfuric acid solutions have been studied. It has been established that interaction takes place between the C=O group and the SO₂OH group in the - and , -sulfonic acids. Possible mechanisms of this interaction for the ionized and covalent compounds have been discussed. It has been shown that all the sulfonic acids retain the anthraquinonoid structure at all sulfuric acid concentrations. It has been concluded that unlike anthraquinone itself, anthraquinonesulfonic acids do not undergo protonation in concentrated sulfuric acid, but form associates with the solvent.     

The ion kinetic energy and mass spectra of isomeric methyl indoles

The mass spectra of the seven isomeric methylindoles were recorded and the [metastable ion]/[daughter ion] ratios for the reactions m/e 130 → m/e 103 and m/e 103 → m/e 77 have been obtained. The ratios indicate that the decomposing [M — 1] ions (m/e 130) from the 4, 5, 6 and 7 isomers are energetically similar as are the [M — 1] ions from the 2 and 3 isomers. The results observed for the m/e → 103 m/e 77 reaction showed that the decomposing m/e 103 ions from the 2, 3, 4, 5, 6 and 7 isomers all have the same energy distribution. N-Methylindole gave ratios which were similar to the 4 to 7 isomers at 70eV but different at 20 eV. The ion kinetic energy (IKE) spectra of all the isomeric methylindoles were also obtained and the results compared with the data obtained from the [metastable ion]/[daughter ion] approach. The results from the IKE spectra indicated that the energy distributions of the [M — 1] and [(M — 1) — HCN] ions from 1-methylindole and the [(M — 1) — HCN] ions from 2-methylindole could readily be distinguished from other isomers whose [metastable ion]/[daughter ion] ratios were similar. Thus by using both techniques certain ambiguities can be resolved.     

The effect of a centrifugal field on a diels-alder reaction

Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, p. 2151, September, 1989.     

The relationship between the crystal structure and optical properties for isomeric aminopyridinium iodobismuthates

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Structural manifestations of the retro diels-alder reaction

Examination of selected cyclohexene derivatives which are fixed into the boat conformation reveals structural deviations from "normal" C-C bond distances consistent with the early stages of the retro Diels-Alder reaction.     

Visible light induced four component reaction of styrene for the access of thiodifluoroesters

The visible light induced multicomponent reaction of styrene, carbon disulfide, amine and ethyl difluorobromoacetate for the synthesis of thiodifluoroesters is disclosed. This developed protocol offers a facile and general route to access various valuable thiodifluoroesters in moderate to good yields. Preliminary mechanistic studies revealed that a radical process might be involved in this transformation.