Olefins deuteriated

Two examples of this method for the synthesis of olefins deuteriated exclusively at the vinyl position by the simple use of deuteriated solvents are shown in equations 64198 and 65199. Due to the alkaline reaction conditions no subsequent isomerization of the initially produced alkene is observed. 

Disubstituted olefins deuteriated at the vinyl positions have been prepared by reduction of diketones with LiAlD4 and pyrolysis of the thiocarbonate. ... 

In certain cases this reduction (with lithium aluminum hydride) takes a different course, and olefins are formed. The effect is dependent on both the reagent concentration and the steric environment of the hydrazone. Dilute reagent and hindered hydrazone favor olefins borohydride gives the saturated hydrocarbon. The hydrogen picked up in olefin formation comes from solvent, and in full reduction one comes from hydride and the other from solvent. This was shown by deuteriation experiments with the hydrazone (150) ... 

Allyl p-tolyl sulphoxide 535 reacts with sodium methoxide in methanol by initial prototropic isomerization and subsequent addition of methanol to give 536 (equation 333). Protic solvents are photochemically incorporated by the open chain olefinic bond of trans methyl )S-styryl sulphoxide 537 in a Markovnikov regiospecificity (equation 334). Mercaptanes and thiophenols add to vinyl sulphoxides in a similar manner (compare also Reference 604 and Section IV.B.3) to give fi-alkylthio(arylthio)ethyl sulphoxides 538 (equation 335). Addition of deuteriated thio-phenol (PhSD) to optically active p-tolyl vinyl sulphoxide is accompanied by a low asymmetric a-induction not exceeding 10% (equation 336) . Addition of amines to vinyl sulphoxides proceeds in the same way giving )S-aminoethyl sulphoxides in good to quantitative yields depending on the substituents at the vinyl moiety When optically active p-tolyl vinyl sulphoxides are used in this reaction, diastereoisomeric mixtures are always formed and asymmetric induction at the p- and a-carbon atoms is 80 20 (R = H, R = Me) and 1.8 1 (R = Me, R = H), respectively (equation 337) ... 

A complicating factor associated with experimental application of the Skell Hypothesis is that triplet carbenes abstract hydrogen atoms from many olefins more rapidly than they add to them. Also, in general, the two cyclopropanes that can be formed are diastereomers, and thus there is no reason to expect that they will be formed from an intermediate with equal efficiency. To allay these problems, stereospecifically deuteriated a-methyl-styrene has been employed as a probe for the multiplicity of the reacting carbene. In this case, one bond formation from the triplet carbene is expected to be rapid since it generates a particularly well-stabilized 1,3-biradical. Also, the two cyclopropane isomers differ only in isotopic substitution and this is anticipated to have only a small effect on the efficiencies of their formation. The expected non-stereospecific reaction of the triplet carbene is shown in (15) and its stereospecific counterpart in (16). 

One of the attractive features about the chemical properties of FL is that it gives a good yield of cyclopropanes with many olefins (M. Jones Jr. et al., 1970 Gaspar et al., 1984). Irradiation of DAF in acetonitrile containing styrene gives the expected cyclopropane in high yield. When deuteriated a-methylstyrene is used, cyclopropanation occurs with partial retention of configuration (Table 6). Similar results are observed for other olefins. 

At first, 1-chlorocyclopropyl phenyl sulfoxide (93) was synthesized from the olefin 92 in three steps in good yield. Treatment of sulfoxide 93 with 2.5 eq of /-PrMgCl in THF at —78 °C for 5 min followed by quenching with CD3OD afforded the deuteriated chlorocy-clopropane (95) in 78% yield with high deuterium incorporation. From this experiment, it was proved that the intermediate of the reaction is a magnesium cyclopropylidene species 94 (equation 26). 

The most comprehensive analysis of /3-diketones125, 1265 proves the Cs symmetry is the correct one for the /3-diketones involving CH3, Ph and CF3 groups. The band assignments are given in Table 12. The effect of deuteriation of the olefinic proton is also noticeable on the modes v(C=C) and v(C-C), especially the latter, but it is the effect of deuteriation on the hydrogen bond which has far reaching implications. 

The latter substrates were deuteriated and mass spectral fragmentation of the products of solvolysis was studied . The authors concluded that both unassisted and Ag" -assisted solvolysis were stereoretentive and that the intermediate cations and the bridgehead olefins do not interconvert. They believe that a perpendicular cation, 58, does not intervene but the precise structure of the intermediates is still uncertain. 

The hemideuteriated isotopomeric cations 25 and 26, obtained in equimolar amounts by addition of methylbis(methylthio)sulphonium hexachloroantimonate 27 to deuteriated olefin, E-t-butyl-t-butyl-D -ethylene 28 (equation 38), have been converted to the non-separable hemideuteriated thietanium ions 29 and 30, characterized spectroscopically. These rearrangements have been followed at 25 °C (over periods of 1-16 weeks) by... 

Enamines (e.g. 377) have been shown to react with conjugated nitroolefins 378 to give mainly dihydro-l,2-oxazine A -oxide derivatives 379 as products of kinetic control (sometimes a cyclobutane ring is formed in these reactions see Section II.B). The stability of these heterocycles is largely dependent on the parent enamine and the type of substituent used on the nitro olefin as has been extensively studied by Valentin and coworkers " . Usually they open into the corresponding nitroalkylated enamines 380 (equation 82), in particular in a solution of methanol or deuteriated chloro-and often an equilibrium between the two forms is established. Stable 1,2-oxazine A -oxides have been obtained in the reaction of 2-nitro-l,3-dienes with cyclic enamines . 

Low-energy electron bombardment of monolayers of ethylene on a silver(lll) surface brings about C—H bond fission. The H is absorbed on the surface and the vinyl radical dimerizes to yield buta-1,3-diene. Higher doses of electrons lead to the formation of ethyne Olefins can undergo catalytic oxidation when they are irradiated in the presence of silver catalysts either as silver powder or supported silver metals on anatase titania, sihca and porous glass. Irradiation under these conditions increases the reaction rate. When the surface is coated with ethene and deuterium, partly deuteriated ethene is formed on irradiation, presumably as a result of a vinyl radical reacting with deuterium. UV... 

Similarly rhodium trichloride reduced by ethanol in the presence of tris-o-tolylphosphine gives an active rhodium(i) catalyst RhClKo-tolyOaPJa, via the characterised rhodium(ii) intermediate RhCl2[(o-tolyl)3P]2. The rhodium(i) in the above three-co-ordinate species can readily abstract a hydrogen atom, even from a second rhodium(i) molecule. Reduction of RhQ3(py)3 by NaBH in DMF yields a catalyst for Irans-deuteriation of olefins. ... 

The acid-induced reaction of aryldiazomethanes with olefins gives arylcyclo-propanes in addition to olefins and esters. The cyclopropanes are formed stereo-specifically and their yields are largest in reactions with olefins which on cation addition give secondary carbonium ion centres. The use of deuteriated acids leads to partial incorporation of deuterium in the cyclopropane adducts, whereas the use of [a- H]-phenyldiazomethane leads to partial loss of deuterium, suggesting a slow proton transfer from the acid to the diazo-compound a carbenoid rather than a free carbene appears to be involved. 

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