Reaction with simple olefins

The molecular XF (X = Br, I) can be readily made from the corresponding elements. In general, the real XFs are more powerful fluorinating agents than their counterparts [XF] and, in addition to somewhat similar reactions with simple olefins, they also add to deactivated enones and ynones (equation 1 13)206. The reaction with acetylenes, which can be carried with either BrF and IF, proceeds to completion, presenting yet another way for constructing the CF2 group (equation 114)207. 

Chloroxy compounds such as C10CF2CFXS02F (X = F CF3) undergo reaction with simple olefins to give ethers (equation 10)23. With unsymmetrical olefins the reaction... 

The reported thermal [4 + 2] cycloaddition of arylmethylenemalon-dialdehydes with electron-rich olefins including enol ethers, ketene acetals, enamines, and cyclopentadiene (benzene, 25°C) or their Lewis acid-catalyzed reaction with simple olefins including isobutylene and 1,1-diphenylethylene (Znl2 catalyst, benzene, 25°C) further illustrates the Diels-Alder rate acceleration accompanying the substitution of an ,/3-unsaturated aldehyde with a C-3 electron-withdrawing group [Eq,... 

Isoindoles undergo the Diels-Alder reaction readily, but there appears to be only one example of the reaction with simple olefins. This is a special, intramolecular, case where the frequency factor is high (Eq. 17).55... 

Cationic polymerization of alkenes and alkene derivatives has been carried out frequently in aqueous media.107 On the other hand, the reaction of simple olefins with aldehydes in the presence of an acid catalyst is referred to as the Prins reaction.108 The reaction can be carried out by using an aqueous solution of the aldehyde, often resulting in a mixture of carbon-carbon bond formation products.109 Recently, Li and co-workers reported a direct formation of tetrahydropyranol derivatives in water using a cerium-salt catalyzed cyclization in aqueous ionic liquids (Eq. 3.24).110... 

Copper(II) triflate has also been used for the carbenoid cyclopropanation reaction of simple olefins like cyclohexene, 2-methylpropene, cis- or rran.y-2-butene and norbomene with vinyldiazomethane 2 26,27). Although the yields were low (20-38 %), this catalyst is far superior to other copper salts and chelates except for copper(II) hexafluoroacetylaeetonate [Cu(hfacac)2], which exhibits similar efficiency. However, highly nucleophilic vinyl ethers, such as dihydropyran and dihydrofuran cannot be cyclopropanated as they rapidly polymerize on contact with Cu(OTf)2. With these substrates, copper(II) trifluoroacetate or copper(II) hexafluoroacetylaeetonate have to be used. The vinylcyclopropanation is stereospecific with cis- and rra s-2-butene. The 7-vinylbicyclo[4.1.0]heptanes formed from cyclohexene are obtained with the same exo/endo ratio in both the Cu(OTf)2 and Cu(hfacac)2 catalyzed reaction. The... 

Jacobsen et al. reported that a different type of dintrogen ligand (48), fe[(2,6-dichlorophenyl)-methylideneaminojcyclohexane, was an efficient chiral ligand for copper-mediated asymmetric aziridination (Scheme 35).154 The reactions of conjugated c/.v-olefins show high enantioselectivity with this catalyst, but enantioselectivity of the reactions of simple olefins such as styrene and indene is moderate. 

Recently, Scott et al. have reported that a Cu complex bearing an axially chiral ligand (49) is an excellent catalyst for aziridination of 2,2-dimethylchromene and cinnamate esters (Scheme 36), though it is also less efficient for the reactions of simple olefins.157,158 On the basis of DFT investigation of the nitrenoid intermediate (50), one of the oxygen atoms of the A -sulfonyl group has been proposed to be interacting with the nitrene N-atom.158... 

The most characteristic reaction of butadiene catalyzed by palladium catalysts is the dimerization with incorporation of various nucleophiles [Eq. (11)]. The main product of this telomerization reaction is the 8-substituted 1,6-octadiene, 17. Also, 3-substituted 1,7-octadiene, 18, is formed as a minor product. So far, the following nucleophiles are known to react with butadiene to form corresponding telomers water, carboxylic acids, primary and secondary alcohols, phenols, ammonia, primary and secondary amines, enamines, active methylene compounds activated by two electron-attracting groups, and nitroalkanes. Some of these nucleophiles are known to react oxidatively with simple olefins in the presence of Pd2+ salts. Carbon monoxide and hydrosilanes also take part in the telomerization. The telomerization reactions are surveyed based on the classification by the nucleophiles. 

The transition metal-catalyzed reaction of diazoalkanes with acceptor-substituted alkenes is far more intricate than reaction with simple alkenes. With acceptor-substituted alkenes the diazoalkane can undergo (transition metal-catalyzed) 1,3-dipolar cycloaddition to the olefin [651-654]. The resulting 3//-pyrazolines can either be stable or can isomerize to l//-pyrazolines. 3//-Pyrazolines can also eliminate nitrogen and collapse to cyclopropanes, even at low temperatures. Despite these potential side-reactions, several examples of catalyzed cyclopropanations of acceptor-substituted alkenes with diazoalkanes have been reported [648,655]. Substituted 2-cyclohexenones or cinnamates [642,656] have been cyclopropanated in excellent yields by treatment with diazomethane/palladium(II) acetate. Maleates, fumarates, or acrylates [642,657], on the other hand, cannot, however, be cyclopropanated under these conditions. 

Double-bond isomerization reaction of simple olefins requires strong basic catalysts. Various catalyst systems have been reported for this reaction. They include sodium-organosodium catalysts prepared in situ by reacting an excess of sodium with a reactive organic compound, such as o-chlorotoluene or anthracene as reported by Pines and co-workers 5-8). 

The reaction is generally applicable to a variety of substrate types, as illustrated in Table I.10 Compatible functionality includes hydroxyl, ester, lactone, acid, ketone, and electron-poor olefins such as those conjugated to a-ketones. Some selectivity between isolated double bonds is also found. The reaction generally gives nearly quantitative yields with simple olefins... 

Historically, reaction of simple olefins in the presence of chiral phosphine-Rh complexes in 1968 marked the first examples of homogeneous asymmetric hydrogenation [6], However, only a few successful results have been reported for asymmetric hydrogenation of unfunctionalized olefins. Some examples with late and early transition-metal complexes are illustrated in Schemes 1.27-28 and Schemes 1.29-30, respectively. 

Dioximato-cobalt(II) catalysts are unusual in their ability to catalyze cyclopropanation reactions that occur with conjugated olefins (e.g., styrene, 1,3-butadiene, and 1-phenyl-1,3-butadiene) and, also, certain a, 3-unsaturated esters (e.g., methyl a-phenylacrylate, Eq. 5.13), but not with simple olefins and vinyl ethers. In this regard they do not behave like metal carbenes formed with Cu or Rh catalysts that are characteristically electrophilic in their reactions towards alkenes (vinyl ethers > dienes > simple olefins a,p-unsaturated esters) [7], and this divergence has not been adequately explained. However, despite their ability to attain high enantioselectivities in cyclopropanation reactions with ethyl diazoacetate and other diazo esters, no additional details concerning these Co(II) catalysts have been published since the initial reports by Nakamura and Otsuka. 

Cyclopropanation of olefins (Simmons-Smith reaction) smoothly proceeds using diethylzinc in combination with diiodomethane. The reaction is much faster with allylic alcohols or its ether derivatives than that with simple olefins. 

In contrast to its ready reaction with acetylenes, Cp2Mo2-(CO)i+ does not react with simple olefins or dienes, e.g., C2Ht+, butadiene, C2H3CN, norbornadiene, etc. With TONE (C2(CN)iJ, 1 is oxidized and [CpMo(C0)il]+ [TONE]7 may be isolated (6). Allene does react, however, to form a complex, ll, in which each of the orthogonal C=C n-bonds donates two electrons to each molybdenum. This fluxional molecule has C2 symmetry in the solid state and has a Mo-Mo bond length of 3.117(1)A (32). 

Isocoumarins. Isocoumarins can be prepared from benzoic acids by orf/jo-thal lation followed by olefination promoted by PdCI. Reaction with simple alkenes requires 1 equiv. of PdCb and a base-catalyzed reaction to effect the final cyclization. The reaction with vinyl halides or acetates generates isocoumarins directly and requires only catalytic amounts of PdCT. 

A related reaction is the substituting addition shown by acceptors such as maleic anhydride with simple olefins. ... 

A2 4 A-i accounts for the possible interrelation between the frequency factors of two monomolecular reactions the formation of a complex four-centere intermediate during the insertion reaction compared with simple olefin desorption The better agreement between the calculated A and experimental Ap values corresponds to the case for which the rate-determining step involves olefin coordination. 

Copper(II) triflate has also been used for the carbenoid cyclopropanation reaction of simple olefins like cyclohexene, 2-methylpropene, cis- or Zra ,s-2-butene and norbomene with vinyldiazomethane 2 Although the yields were low (20-38 %),... 

The reaction of simple olefins with S03 and S03 complexes and derivatives has been demonstrated to yield allylic and vinylic sulfonic acids, hydroxysulfonic acids, and other neutral products (10). The product distribution is a function of olefin type, sulfonation reagent, solvent, and reaction conditions. 

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