Nonconjugate Olefins

In benzene or similar solvents, tris(triphenylphosphine)halogenorhodium(I) complexes, RhX[P(C6H5)3]3, are extremely efficient catalysts for the homogeneous hydrogenation of nonconjugated olefins and acetylenes at ambient temperature and pressures of 1 atmosphere (6). Functional groups (keto-, nitro-, ester, and so on) are not reduced under these conditions. 

This method provides a convenient synthesis of alkenes with the double bond in a relatively unstable position. Thus reduction of the p-toluenesulfonylhydrazones of a,(3-unsaturated aryl ketones and conjugated dienones gives rise to nonconjugated olefins. Unsaturated ketones with endocyclic double bonds produce olefins with double bonds in the exocyclic position. The reduction of p-toluenesulfonylhydrazones of conjugated alkynones furnishes a simple synthesis of 1,3-disubstituted allenes. ... 

The epoxidation of nonconjugated olefins is slow123,124 and shows reduced enantioselectivity as compared with the epoxidation of conjugated olefins. For example, enantioselectivities from the epoxidation of (Z)-l-cyclohexyl-1-propene, 3,3-dimethyl-l-butene, and geranyl acetate are 82% (with (34)), 70% (with (34)),123 and 53% (6,7-epoxide, with (26)),124 respectively, and yields of the epoxides are modest. 

Kim et al. have reported that the copper complex bearing the unique dinitrogen ligand (51) catalyzes the aziridination of conjugated as well as nonconjugated olefins with good enantio-selectivity (Scheme 37).159... 

MMI/MMPI incorporates a modified Newton-Raphson energy minimization algorithm that moves atoms one by one and is quite efficient. The force field is parameterized not only for saturated hydrocarbons including cyclopropane, but also for nonconjugated olefins (17c),... 

The acyl radical equivalents formed by the electroreduction of acyl phosphonium salts have an interesting reactivity and the electroreduction of nonconjugated olefinic acids yields intramolecular coupling products (Scheme 28) [11, 54, 55]. 

Reductive cyclizations of nonconjugated olefinic ketones (see Scheme 8) [12] or... 

Both conjugated and nonconjugated olefins form complexes with the transition-metal carbonyls. Despite the fact that the first known complex, Zeises salt K(PtC2H4Cl3), discovered in 1827, was that of a simple olefin, complexes of monoolefins are rather limited in number. However, nonconjugated diolefins (L) react with group-VI carbonyls to form complexes of the type LM(CO)4 an example is provided by tetracarbonyl-bicyclo-(2,2, l)hepta-2,5-diene chromium (2) (Fig. 1). In contrast, the iron carbonyls... 

It is only very recently that much work has been reported on sensitized cis-trans isomerizations of nonconjugated olefins, probably because the spectroscopic triplet energy of ethylene seemed so much... 

Intramolecular photoaddition has been observed in nonconjugated olefins. Thus irradiation of Formula 410 gives the cage structure of Formula 411 (181). Two isomers of the hexachlorocyclopentadiene-cyclooctatetraene adduct give analogous cage structures on irradiation... 

The bromonium ion concept does rationalize the stereochemistry of bromine additions to double bonds very satisfactorily if it is recognized that olefins that can form highly stabilized carbocations need not form such a structure. As al-ready noted, nonconjugated olefins give predominantly anti addition. Cornu-gated olefins, in which the intermediate carbocation would be stabilized by Resonance- however, give a mixture of svn and anti adducts. 

There is, however, other evidence that speaks for the bromonium ion concept and against competition between AdE2 and Ad3 pathways.35 We have already noted that, in polar solvents, addition of bromine to multiple bonds is first-order in bromine when bromine is present in low concentration. Moreover, as Table 7.7 shows, increasing the number of substituents on the double bond cumulatively increases the rate of bromination of nonconjugated olefins in polar solvents irrespective of whether each new substituent is on the same or on the other olefinic carbon as the last.36 Dubois has found that the bimolecular rate constants for addition of bromine to alkyl substituted ethylenes are correlated by... 

Dilling, W. L. Intramolecular photochemical cycloaddition reactions of nonconjugated olefins. Chem. Rev. 66, 373 (1966). 

Mercury(II) trifluoroacetate finds frequent employment in organic synthesis 223, 229, 230) since it adds rapidly, stereospecifically, and quantitatively across nonconjugated olefinic bonds, for example, Eq. (21). The mercurated products thus prepared may be readily converted... 

Olefinic alcohols are best prepared by the action of lithium aluminum hydride on the corresponding acid or ester as in the preparation of 3-penten-l-ol (75%). The double bond may be in the a,/S-position to the ester group, The Bouveault-Blanc procedure has also been used with success for reduction of nonconjugated olefinic esters. The addition of the sodium to an alcoholic solution of the ester is superior to the reverse addition of. the ester to sodium in toluene for the preparation of 2,2-dimethyl-3-buten-l-ol (62%). Selective catalytic hydrogenation is inferior. Large amounts of catalyst are required, and the products contain saturated alcohols. ... 

Formation of endoperoxides of type 178 can be interpreted as a L,4s + cycloaddition that involves singlet oxygen and therefore constitutes a photochemical reaction. Similarly, formation of hydroperoxides from nonconjugated olefins with an allylic hydrogen generally appears to be a concerted ene reaction as indicated in Scheme 65. Other mechanisms have... 

Nonconjugate Olefins The presence of the chiral ligands within the reagent does influence selectivity with substrates containing more than one olefin. The reactivity of the chiral agents is low with tetrasubstituted alkenes, but otherwise it is usually the more electron-rich alkene that reacts faster (Figure 3.5) [6, 257]. 

In addition to propylene, other nonconjugated olefins have been copolymerized with CO using enantiopure palladium catalysts. Allylbenzene, 1-butene, 1-heptene, 4-methyl-l-pentene, and cis-2-butene [84,85] as well as hydroxy- and carboxylic acid-functionalized monomers [87] have been polymerized to give optically active polymers. Waymouth, Takaya and Nozaki have recently reported the enantioselective cyclocopolymerization of 1,5-hexadiene and CO [88,89]. 

O. Ermer and S. Lifson, /. Am. Chem. Soc., 95,4121 (1973). Consistent Force Field Calculations. III. Vibrations, Conformations, and Heats of Hydrogenation of Nonconjugated Olefins,... 

An indirect PET methodology known as redox photosensitization has been developed by Majima et al. [136] and Tazuke and Kitamura [137] for achieving higher yields of nucleophilic addition products to alkene radical cations. One interesting example of this approach may be cited by illustrating anti-Markonikov alcohol addition to nonconjugated olefin (159) using biphenyl as cosensitizer [138]. The complete reaction sequence is shown in Scheme 34. More examples on this topic may be found in Refs. 4 and 5. 

In addition to propylene, other nonconjugated olefins have been copolymerized with CO using enantiopure palladium catalysts. Allylbenzenes,... 

Nonconjugated olefins, acetylenes, styrenes, a,P-unsaturated aldehydes, a,P-unsaturated ketones, a,P-unsaturated acids and quinones are all arylated under Meerwein conditions. Conjugated dienes and ene-ynes can be also used as substrates. 

Isomerization of a nonconjugated olefin to a conjugated olefin by Fe(CO)5 is shown in equation (7-4). 

Lifson, S. Warshel, A. Consistent force field for calculations of conformations, vibrational spectra and enthalpies of cycloalkane and n-alkane molecules, J. Chem. Phys. 1968, 49, 5116-5129 Ermer, O. Lifson, S. Consistent force field calculations. III. Vibrations, conformations and heats of hydrogenation of nonconjugated olefins, J. Am. Chem. Soc. 1973,95,4121 132. 

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