Hydrovinylation Reaction Research Articles

The Palladium-Catalyzed Hydroarylation and Hydrovinylation of Tertiary 3-(o-Acetoxyaryl)- and 3-(o-Benzoyloxyaryl)propynols − A Route to 4-Aryl- and 4-Vinyl-2,2-Dimethyl-3-chromenes

The palladium-catalyzed hydroarylation and hydrovinylation of tertiary 3-(o-acetoxyaryl)- and 3-(o-benzoyloxyaryl)propynols provides a regio- and stereoselective route to allylic alcohols with aryl and vinyl substituents which can be readily converted into the corresponding chromene derivatives. The hydroarylation and hydrovinylation reaction is believed to proceed through a carbopalladation step whose regiochemistry is primarily controlled by the directing effect of the tertiary hydroxy group.

Phosphino carboxylic acid ester functionalized carbosilane dendrimers: nanoscale ligands for the Pd-catalyzed hydrovinylation reaction in a membrane reactor

Phosphino carboxylic acid ester terminated G(0) compounds Si(CH(2))(3)SiMe(2)(C(6)H(4)CH(2)OC(O)(CH(2))(n)()CH(2)PPh(2)(4) (9a and 9b; n = 1, 2) and the carbosilane dendrimers Si(CH(2))(3)Si((CH(2))(3)SiMe(2)(C(6)H(4)CH(2)OC(O)(CH(2))(n)()CH(2) PPh(2))(3)(4) (10a and 10b; n = 1, 2) have been prepared as hemilabile nanoscale ligands for the palladium-catalyzed codimerization of olefins. The hydrovinylation of styrene was carried out in a continuously operated nanofiltration membrane reactor. Under continuous conditions, the selectivity of the reaction is increased considerably. Monomeric model complexes and the dendritic catalysts were compared for their activity and selectivity in batch reactions. The Pd catalyst complexes were prepared in situ from the dendritic ligands and an (allyl)palladium(II) precursor.

Hydrovinylation and Related Reactions: New Protocols and Control Elements in Search of Greater Synthetic Efficiency and Selectivity

New reaction conditions and stereochemical control elements for heterodimerization between ethylene (or propylene) and functionalized vinyl arenes are highlighted (see equation). For example, an enantioselective version of the hydrovinylation reaction uses [{(allyl)NiBr}2], a noncoordinating counter anion, (bis-CF3−C6H3)4B−, and a hemilabile ligand such as MOP. Other applications include intramolecular cyclization of 1,6-dienes and heterodimerization of norbornene and ethylene.

Hydrovinylation and [2+2] Cycloaddition Reactions of Alkynes and Alkenes Catalyzed by a Well-Defined Cationic Ruthenium−Alkylidene Complex

The cationic ruthenium−alkylidene complex [(PCy3)2(CO)(Cl)RuCHCHC(CH3)2]+BF4- (1) was found to catalyze both hydrovinylation and [2+2] cycloaddition reactions of alkynes and alkenes. The reaction of R‘C⋮CR‘ ‘ (R‘ = H, Ph, n-Pr; R‘ ‘ = Ph, n-Pr, p-Tol, SiEt3, CH2CH2OH) with ethylene in the presence of 1 (3 mol %) produced the hydrovinylation products 2 and 3. The analogous reaction of dimethyl acetylenedicarboxylate (R‘ = R‘ ‘ = CO2Me) with ethylene and norbornene resulted in the formation of the [2+2] cycloaddition products 4. Based on the experimental evidence, a plausible mechanism of the hydrovinylation reaction has been proposed via a sequential insertion of alkyne and ethylene to the hydride complex 7.

ChemInform Abstract: The Hydrovinylation Reaction: A New Highly Selective Protocol Amenable to Asymmetric Catalysis.

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The Hydrovinylation Reaction: A New Highly Selective Protocol Amenable to Asymmetric Catalysis

Carbon-carbon bond forming reaction is arguably the most important type of bond construction in organic chemistry; yet, paucity of methods for the stereoselective incorporation of abundantly available carbon feedstocks such as CO, CO2, HCN, or simple olefins to prochiral substrates is one of the major limitations in this area.1 One potentially important class of such reactions is the cationic [Ni-H]+-catalyzed olefin dimerization reaction.2,3 There had been only limited success in finding an enantioselective variation of this reaction partly because of the competing oligomerization of starting olefins and isomerization of the primary products (eq 1). In this paper we report our initial

Hydrovinylation of olefins catalyzed by cationic nickel complexes [Ni(2,4,6-Me3C6H2) (CH3CN) P2]BF4

Abstract The hydrovinylation of several olefins and alkynes by the ionic nickel precursor trans -[Ni(2,4,6-Me 3 C 6 H 2 )(CH 3 CN)(P(CH 2 Ph) 3 ) 2 ]BF 4 in THF solution was studied. The activity of the catalytic system showed strong dependence on the nature of the substrate. Only conjugated diolefins and some strained mono-olefins led to hydrovinylation products with nearly complete conversion, Selectivity was also variable: for norbornene, exo -2-vinylnorbornane (94%) was obtained selectively, whereas isoprene gay e a mixture of 9 hydrovinylation compounds. The turnover rate of the reaction at 25°C and 15 bar of initial pressure of ethylene with an olefin/[Ni] ratio of 1000/1 was 4300 h −1 for norbornene and 30 h −1 for isoprene. The chiral monodentate phc sphines, ( cis -myrtanyl)diphenylphosphine and myrtenyldiphenylphosphine, were obtained. The catalytic precursors containing these phosphines were being tested in the hydrovinylation of styrene and norbornene, and the enantiomeric excess obtained was between 3–7%. Diphenylacetylene was also found to be active in the hydrovinylation reaction; cis - and trans -3,4-diphenyl-1,3-hexadiene, products of a double vinylation of the triple bond were obtained.

Applications of Zr-Catalyzed Carbomagnesation and Mo-Catalyzed Macrocyclic Ring Closing Metathesis in Asymmetric Synthesis. Enantioselective Total Synthesis of Sch 38516 (Fluvirucin B1)

The first enantioselective total synthesis of antifungal agent Sch 38516, also known as fluvirucin B1, is described. The synthesis includes a convergent asymmetric preparation of amine 17 and acid 18, which are then united to afford diene 62. Metal-catalyzed transformations play a crucial role in the synthesis of the latter moiety. Of particular note are the diastereo- and enantioselective Zr-catalyzed alkylations, a tandem Ti- and Ni-catalyzed process that constitutes a hydrovinylation reaction, and a Ru-catalyzed alcohol oxidation to afford carboxylic acid 18. The requisite carbohydrate 38 is synthesized in a highly diastereo- and enantioselective fashion. Optical purity of the carbohydrate moiety arises from the use of the asymmetric dihydroxylation method of Sharpless; diastereochemical control is achieved through a selective dipolar [3 + 2] cycloaddition with a readily available amine serving as the chiral auxiliary. Union of the appropriately outfitted carbohydrate 71 and diene 62 through an efficient and diastereoselective glycosylation is followed by a remarkably efficient Mo-catalyzed macrocyclization that proceeds readily at room temperature.

Hydrovinylation of styrene derivatives to 3-aryl-1-butenes catalysed by nickel complexes

The hydrovinylation of styrene and ring-substituted styrene molecules by the ionic nickel precursor trans-[Ni(2,4,6-Me3C6H2) (CH3CN) (P(CH2Ph)3)2]BF4 in THF solution has been investigated. The chemoselectivity towards hydrovinylation products is about 99%. For styrene the conversion is nearly complete and the regioselectivity towards the vinylation in the α-position in the conjugated aryl olefin derivatives is 100%. The yield of 3-phenyl-1-butene reaches 97% with minor amounts of the isomerization products cis- and trans-2-phenyl-2-butene. The turnover rate of the reaction at 25°C, 15 bar (initial pressure) of ethylene with a styrene/[Ni] ratio 1000/1 is 1915 h−1. With styrene derivatives substituted in the vinyl fragment, the hydrovinylation reaction was very limited; however those substituted in the phenyl fragment (ArCH=CH2; Ar:p- and m-Me(C6H4), p- and m-Et(C6H4), p-and m-vinyl(C6H4), p- and m-Cl(C6H4), p-MeO(C6H4) and m-NO2(C6H4)) showed similar selectivity to styrene but different turnover rates. Activity decreases with the substituent in the sequence Cl∼OMe∼CH=CH2∼H∼CH2CH3&>;Me&>;NO2 related with the coordination ability of the olefin. Activity of the para derivatives is slightly higher than that of the meta analogues. The ionic compound [Ni(2,4,6-Me3C6H2) (CH3CN) ((PhCH2)2PCH2CH2P(CH2Ph)2)]BF4 and the neutral trans-[NiBr(2,4,6-Me3C6H2) (P(CH2Ph)3)2] do not show any activity in the codimerization reaction of styrene and ethylene in the same conditions.