89039-12-3

Upstream product

• 54159-16-9 (2-<2H1>)-4-methoxyphenylethyne 
• 6303-59-9 (Z)-1-bromo-2-(4-methoxyphenyl)ethene 
• 637-69-4 4-Methoxystyrene 
• 768-60-5 4-methoxyphenylacetylen 
• 943-89-5 (E)-3-(4-methoxyphenyl)acrylic acid 
• 6303-59-9 (E)-4-(2-bromo-vinyl)-anisole 
• 89039-13-4 (E)-β-deuterio-1-methoxy-4-vinylbenzene 
• 123-11-5 4-methoxy-benzaldehyde 

Relevant academic research and scientific papers

cis-Semihydrogenation of alkynes with amine borane complexes catalyzed by gold nanoparticles under mild conditions

Supported gold nanoparticles catalyze the semihydrogenation of alkynes to alkenes with ammonia borane or amine borane complexes in excellent yields and under mild conditions. Internal alkynes provide cis-alkenes, making this protocol an attractive alternative of the classical Lindlar's hydrogenation.

On the Origin of E/Z Selectivity in the Modified Julia Olefination - Importance of the Elimination Step

The mechanism and origin of high E selectivity in the modified Julia olefination of aromatic aldehydes have been explored by computational and experimental means. Reversibility of addition and hence selectivity of the formation of sulfinate 5 is very variable and depends on the nature of the sulfone substrate. However, in all cases, elimination occurs through a concerted antiperiplanar and synperiplanar mechanism for sulfinates anti-5 and syn-5, respectively. Both syn and anti diastereomeric pathways thus lead preferentially to the (E)-alkene. Copyright

Site-selective deuterated-alkene synthesis with palladium on boron nitride

Heavy stuff: A triethylamine-mediated H-D exchange reaction for the conversion of unlabeled alkynes (1) into [D1]alkynes ([D 1]-1) in a mixture of D2O/THF has been developed. Furthermore, the efficient preparation of site-

Construction of 2,3-dihydrofuran cores through the [3+2] cycloaddition of gold α-carbonylcarbenoids with alkenes

Treatment of 2-epoxy-1-alkynylbenzenes with electron-rich alkenes and a [AuCl(PR3)]/AgX catalyst in CH2Cl2 led to the formation of 2-alkenyl-1-(2,3-dihydrofuran-4-yl)benzenes. This transformation comprises of a gold-catalyzed redox reaction to form a gold α- carbonylcarbenoid initially, which then reacts in situ with an alkene in a [3+2] cycloaddition. A range of alkenes are amenable to this tandem reaction, amongst them α-sub-stituted styrenes, enol ethers, and 2,3dimethylbutadienes. Deuterium-labeling experiments suggest a stepwise mechanism for the α-carbonylcarbenoid/alkene [3+2] cycloaddition. The resulting 2,3-dihydrofuran products allow access to diverse oxacyclic compounds through a stereoselective ene-oxonium reaction initiated by treatment with HOTf (1mol%; Tf= trifluoromethanesulfonyl). A stepwise pathway is proposed for this reaction. The feasibility for direct transformation of 2-alkenyl-1-alkynylbenzenes into the desired 2,3-dihydrofuran products through initial m-chloroperbenzoic acid oxidation, followed by the addition of gold catalyst and alkene, has also been demonstrated.

Mechanism of the [2 + 2] photocycloaddition of fullerene C60 with styrenes

Stereochemical studies on [2 + 2] photoaddition of cis-/trans-4-propenylanisole (cis-1 and trans-1) and cis-1-(p-methoxyphenyl)ethylene-2-d1 (cis-3-d1) to C60 exhibit stereospecificity in favor of the trans-2 cycloadduct in the former case and nonstereoselectivity in the latter. The observed stereoselectivity in favor of the cis-6-d3 [2 + 2] diastereomer by 12% in the case of the photochemical addition of (E)-1-(p-methoxyphenyl)-2-methyl-prop-1-ene-3,3,3-d3 (trans-5-d3) to C60 is attributed to a steric kinetic isotope effect (k(H)/k(D) = 0.78). The loss of stereochemistry in the cyclobutane ring excludes a concerted addition and is consistent with a stepwise mechanism. Intermolecular secondary kinetic isotope effects of the [2 + 2] photocycloaddition of 3-d0 vs 3-d1, and 3-d6 as well as 5-d0 vs 5-d1, and 5-d6 to C60 were also measured. The intermolecular competition due to deuterium substitution of both vinylic hydrogens at the β-carbon of 3 exhibits a substantial inverse α-secondary isotope effect k(H)/k(D) = 0.83 (per deuterium). Substitution with deuterium at both vinylic methyl groups of 5 yields a small inverse k(H)/k(D) = 0.94. These results are consistent with the formation of an open intermediate in the rate-determining step.

Vinylborane formation in rhodium-catalyzed hydroboration of vinylarenes. Mechanism versus borane structure and relationship to silation

Attempted catalytic hydroboration of (4-methoxyphenyl)ethene 1 with R,R-3-isopropyl-4-methyl-5-phenyl-1,3,2-oxazaborolidine 6 proceeded extremely slowly relative to the 3-methyl analog 2 derived from φ-ephedrine when diphosphinerhodium complexes were employed. With phosphine-free rhodium catalysts, especially the 4-methoxy-phenylethene complex 7, the reaction proceeded rapidly and quantitatively to give only the corresponding (E)-vinylborane 9 and 4-methoxyethylbenzene 8 in equimolar amounts. Isotopic labeling and kinetic studies demonstrated that this reaction pathway is initiated by the formation of a rhodium hydride with subsequent reversible and regiospecific H-transfer to the terminal carbon, giving an intermediate which adds the borane and then eliminates the hydrocarbon product. Further migration of the secondary borane fragment from rhodium to the β-carbon of the coordinated olefin occurs, followed by Rh-H β-elimination which produces the vinylborane product and regenerates the initial catalytic species. When the same catalytic reaction is carried out employing catecholborane in place of the oxazaborolidine, an exceedingly rapid turnover occurs. The products are again 4-methoxyethylbenzene and the (E)-vinylborane 23 but accompanied by the primary borane 24 in proportions which vary with the experimental conditions. None of the secondary borane, which is the exclusive product when pure ClRh(PPh3)3 is employed as catalyst, is formed. The product variation as a function of initial reactant concentration was fitted to a model in which the rhodium-borane intermediate in the catalytic cycle undergoes two competing reactions-β-elimination of Rh-H versus addition of a further molecule of catecholborane. The model demonstrates that a kinetic isotope effect of 3.4 operates in the β-elimination step, but none is evident in the addition of catecholborane B-D to rhodium. A similar analysis was successfully applied to the catalytic hydrosilylation of 4-methoxystyrene, with HSiEt3, again employing the phosphine-free rhodium catalyst 7; the product distribution between primary silane 29 and vinylsilane 28 was successfully predicted. The results intimate that silation (i.e., the formation of vinylsilanes under the conditions of catalytic hydrosilylation) can best be explained by a Rh-H based mechanistic model rather than the commonly assumed variant on the Chalk-Harrod catalytic cycle. They provide an explanation for the "oxygen effect" on the rate of Rh-catalyzed hydrosilylations.