Catalytic unactivated olefins

Although sulfonyl chlorides add readily to unactivated olefins, with vinylic monomers telomeric and/or polymeric products were observed. This difficulty has been overcome by carrying out the addition in the presence of catalytic amounts of CuCl2, so as to provide a general and convenient synthesis of /5-chlorosulfones (Asscher-Vofsi reaction)63. For the copper-catalyzed system a redox-transfer mechanism has been suggested in which the... 

Stereoselectivity in homogeneous catalytic reactions is well documented. Oftentimes mechanisms can be postulated regarding individual steps in contrast to heterogeneous systems. A recent detailed investigation of the stereoselective formation of C-C bonds catalyzed by (C5H5)2ZrCl2 has been reported by Hoveyda and Xu.12 The initial step in these reactions is the addition of an alkyl Grignard reactant to an unactivated olefin followed by further bond formation as in Equation (Eq.) [I] 12... 

Addition of an alkyl Grignard to an unactivated olefin in the presence of a catalytic amount of Cp2ZrCl2 [91] leads to the corresponding carbometallated product in good yield [92] (Scheme 7-79). 

Scheme 4.7 Catalytic hydrogenation of unactivated olefins with f PDI)Fe(N2)2-...

In contrast, unactivated olefins and alkynes complexed to organopalladium species generated in situ by oxidative addition of an unsaturated halide to a palladium(0) complex react intramolecularly with stabilized nucleophiles. These reactions that require catalytic quantities of the metal result in overall difunctionalization of the olefinic or acetylenic substrates. 

We recently reported [134, 135] the first successful example of a catalytic amination of an unactivated olefin by nitroarenes under CO pressure. The reduction of aromatic nitro compounds by CO catalysed by Ru3(CO)i2 in the presence of DIAN-R (R = H, Me, OMe, Cl), in cyclohexene as solvent and at 160 °C and 40 bar, gives the corresponding allylamine derivatives as the main products (eq. 29, Table 6) ... 

Carbopalladation Reactions. The transition metal-induced addition of carbon nucleophiles to unactivated alkenes is an attractive area of research. Although the addition of stabilized carbon nucleophiles or an alkoxycarbonyl group across the C=C bond of an unactivated olefin was initially achieved in the presence of stoichiometric amount of Pd salts, such as Pd(OAc)2 or PdCl2(CH3CN)2, more recently this reaction has been achieved catalytically. 

The atom-economic addition of NHj to unactivated olefins is hampered by various obstacles, and in view of the importance of this hydroamination reaction, enormous efforts have been undertaken to develop metal-based catalytic routes [27]. 

Using a combination of AuClg/AgOTf as the catalytic system, Jean and Weghe realized a gold-catalyzed intramolecular hydroarylation of unactivated olefins, which provided a facile access to dihydrobenzopyrans, tetralins, and tetrahydro-quinolines 122 (Scheme 12.53) [57]. A variety of homoallyl aryl ethers 121 with... 

A ruthenium based catalytic system was developed by Trost and coworkers and used for the intermolecular Alder-ene reaction of unactivated alkynes and alkenes [30]. In initial attempts to develop an intramolecular version it was found that CpRu(COD)Cl catalyzed 1,6-enyne cycloisomerizations only if the olefins were monosubstituted. They recently discovered that if the cationic ruthenium catalyst CpRu(CH3CN)3+PF6 is used the reaction can tolerate 1,2-di- or tri-substituted alkenes and enables the cycloisomerization of 1,6- and 1,7-enynes [31]. The formation of metallacyclopentene and a /3-hydride elimination mechanism was proposed and the cycloisomerization product was formed in favor of the 1,4-diene. A... 

Other Reductions. The (porphinato)irons could realize the reduction of alkenes and alkynes with NaBILj. Various unsaturated carbon-carbon bonds were saturated by meso-tetraphenylporphinatoiron chloride (TPPFe Cl) derivatives (up to 81% yield). Ruthenium(III) complexes also pair with NaBH in the reduction of unsaturated carbon-carbon bonds (as does cobalt boride). In the presence of a catalytic amount of Ru(PPh3)4H2 (0.5-1 mol %) and NaBHj, unsaturated carbon-carbon bonds in a wide variety of alkenes and alkynes were saturated in toluene at 100 Addition of water was required to provide a proton source. Similar systems with RUCI3 in aqueous solution reduce unsaturated bonds under milder conditions. Various unactivated mono- or disubstituted olefins and activated trisubstituted olefins were reduced with RUCI3 (10 mol %) and NaBH4 in THF-H2O at 0 °C to room temperature (eq 36). When the RuCl3-catalyzed reductions of olefins were carried out in aqueous amide solution, unactivated trisubstituted olefins were also hydrogenated. ... 

Widenhoefer and Han have reported an effective protocol for the intramolecular hydroamination of unactivated C=C bonds with carbamates [52]. As an example of this protocol, treatment of the N-y-alkenyl carbamate 76 with a catalytic 1 1 mixture of [P(f-Bu)2(o-biphenyl)]AuCl and AgOTf (5 mol%) in dioxane at 60 C for 22 h formed pyrrolidine 77 in 91% isolated yield as a 3.6 1 mixture of diastereomers (Eq. (11.43)). The protocol tolerated substitution at the internal olefinic carbon atom and along the alkyl backbone and the method was applied to the synthesis of both heterobicyclic compounds and piperidine derivatives. This protocol was subsequently expanded to include the intramolecular hydroamination of N-alkenyl carboxamides including 2-allyl aniline derivatives (Eq. (11.44)) [53]. 

Abstract A number of transition metal complexes are capable of catalyzing selective olefination of carbonyl compounds, including aldehydes, activated and unactivated ketones, with diazo reagents in the presence of triphenylphosphine or related tertiary phosphines. These catalytic olefination reactions can be carried out in a one-pot fashion under neutral conditions with the use of different diazo reagents as carbene sources, typically affording olefins in high yields and high stereoselectivity. 

Kiihn and coworkers [19] extended the MTO catalytic system to ketone substrates. Benzoic acid additive was needed to activate the ketones, a strategy that was first developed by Zhang and coworkers [20] in their investigation of olefination of unactivated ketones using an iron-based catalyst In contrast to the -selectivity observed for the iron-based system, MTO-catalyzed olefination of ketones favored Z-olefin products (Scheme 4). Up to 89/11 Z/ selectivity... 

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