Trans Product Research Articles

Cyclometalated C^C* Platinum(IV) NHC Complexes.

We present a previously unknown series of cyclometalated platinum(IV) NHC complexes, obtained by oxidative addition of iodine, iodomethane, and different benzyl bromides to platinum(II) complexes with cyclometalated C^C* dibenzofuran, dibenzothiophene, and phenylimidazole ligands together with an acetylacetonate ligand. All compounds were characterized by standard techniques (1H, 13C, and 195Pt NMR and elemental analysis), and for three complexes, solid-state structures could be obtained. DFT calculations (B3LYP(d3)/def2-TZVPP including dispersion interactions in dichloromethane and acetone) were performed to investigate the mechanism of the oxidation and explain the exclusive formation of the observed trans products.

Biological effects of trans, trans-farnesol in Leishmania amazonensis.

Farnesol, derived from farnesyl pyrophosphate in the sterols biosynthetic pathway, is a molecule with three unsaturations and four possible isomers. Candida albicans predominantly secretes the trans, trans-farnesol (t, t-FOH) isomer, known for its role in regulating the virulence of various fungi species and modulating morphological transition processes. Notably, the evolutionary divergence in sterol biosynthesis between fungi, including Candida albicans, and trypanosomatids resulted in the synthesis of sterols with the ergostane skeleton, distinct from cholesterol. This study aims to assess the impact of exogenously added trans, trans-farnesol on the proliferative ability of Leishmania amazonensis and to identify its presence in the lipid secretome of the parasite. The study involved the addition of exogenous trans, trans-farnesol to evaluate its interference with the proliferation of L. amazonensis promastigotes. Proliferation, cell cycle, DNA fragmentation, and mitochondrial functionality were assessed as indicators of the effects of trans, trans-farnesol. Additionally, lipid secretome analysis was conducted, focusing on the detection of trans, trans-farnesol and related products derived from the precursor, farnesyl pyrophosphate. In silico analysis was employed to identify the sequence for the farnesene synthase gene responsible for producing these isoprenoids in the Leishmania genome. Exogenously added trans, trans-farnesol was found to interfere with the proliferation of L. amazonensis promastigotes, inhibiting the cell cycle without causing DNA fragmentation or loss of mitochondrial functionality. Despite the absence of trans, trans-farnesol in the culture supernatant, other products derived from farnesyl pyrophosphate, specifically α-farnesene and β-farnesene, were detected starting on the fourth day of culture, continuing to increase until the tenth day. Furthermore, the identification of the farnesene synthase gene in the Leishmania genome through in silico analysis provided insights into the enzymatic basis of isoprenoid production. The findings collectively offer the first insights into the mechanism of action of farnesol on L. amazonensis. While trans, trans-farnesol was not detected in the lipid secretome, the presence of α-farnesene and β-farnesene suggests alternative pathways or modifications in the isoprenoid metabolism of the parasite. The inhibitory effects on proliferation and cell cycle without inducing DNA fragmentation or mitochondrial dysfunction raise questions about the specific targets and pathways affected by exogenous trans, trans-farnesol. The identification of the farnesene synthase gene provides a molecular basis for understanding the synthesis of related isoprenoids in Leishmania. Further exploration of these mechanisms may contribute to the development of novel therapeutic strategies against Leishmania infections.

Preparation, characterization and stability of water-in-oil Pickering emulsions stabilized by acylated EGCG derivatives

Excessive intake of trans and saturated fatty acids from solid fats contributes to the development of chronic diseases. Food-grade water-in-oil (W/O) emulsions for the replacement of trans and saturated fat products, delivery of active compounds and microreactors remain to be further explored. Camellia oil-based W/O Pickering emulsions were prepared using acylated EGCG derivatives with various carbon chain lengths, including EGCG myristate (MYR-E), EGCG palmitate (PAL-E), and EGCG stearate (STEA-E). The acylated EGCG derivatives exhibited a contact angle of 90–100° with water droplets and could theoretically be used as Pickering emulsion stabilizers. The acylated EGCG derivatives were dissolved in the oil phase as needle-like crystals, which stabilized the emulsion against aggregation by adsorption at the oil-water interface. Pickering emulsions developed with STEA-E (PE-STEA) maintained higher stability after three freeze-thaw cycles, with a creaming index (CI) of 0% at oil-water volume ratios greater than 4:6. PE-STEA with varying oil-water volume ratios were stable at room temperature and 4 °C after long-time storage, with a maximum CI of only 1.39%. This study could provide new perspectives on the application of acylated EGCG derivatives and broaden the application of surfactant-free W/O Pickering emulsions in the food industry.

TfOH‐Catalyzed Highly Regioselective Synthesis of Conjugated Enones by Coupling of Alkynes and Aldehydes

AbstractTriflic acid‐catalyzed regioselective enone synthesis from intermolecular coupling of aldehydes and alkynes has been developed. The present reaction is very efficient, effective, simple in nature and mild. The substrate scope is very diverse. This metathesis reaction exclusively provided trans product using aryl and aliphatic aldehydes and internal and terminal alkynes.

Intermediate-catalyzed mechanism for the bromination of alkenes

A mechanism is proposed for the fast product-forming step of the bromination of alkenes in which a bromonium ion catalyzes the formation of a vicinial dihalide product. Energy profiles for this step of the syn and anti addition of molecular bromine to alkenes with various levels of substitution at the double bond were investigated using density functional theory calculations. Our calculations were able to reproduce experimentally observed trends in reactivity as a function of double-bond substitution. We additionally demonstrate that the anti addition is kinetically more favorable and results in the trans product, in agreement with experiment. The mechanism described here provides another route to the halogenated product which does not necessitate the formation of a new counteranion for each product molecule that is formed, and the highly exothermic nature of this step could serve to drive other reactions forward in a similar way.

Regio‐ and Stereoselective, Intramolecular [2+2] Cycloaddition of Allenes, Promoted by Visible Light Photocatalysis

AbstractEnallenylamides have been utilized for the synthesis of heterobicycle[4.2.0]octane derivatives via Ir/hν promoted [2+2] cycloaddition reaction. The reaction specifically targets the distal double bond of the allene moiety, and results in the exclusive formation of the trans product. The process is conducted at room temperature and under an inert atmosphere. An extensive study on the substituent propensities during the cycloaddition step revealed variable effects. Electron‐withdrawing groups conjugated with the double bond participating in the cycloaddition either hindered the process or reduced its yield. Conversely, electron‐donating substituents enhanced the efficiency, resulting in product yields ranging from 60% to 88%. Our study also demonstrated the influence of protecting groups on the reaction pathway.

Facet-dependent Pd0-O2−-Ce3+ active site for selective hydrogenation of linoleate ester to cis oleic acid ester

Reducing the formation of trans fatty acid in vegetable oil hydrogenation process is of significance to ensure food safety. Herein, Pd0-O2−-Ce3+ active site was constructed by strong electronic interactions between Pd0 and CeO2-Polyhedrons to promote the formation of cis fatty acid. Results reveal that the abundant oxygen vacancies of CeO2 (111) facets promote the adsorption and activation of hydrogen, leading to excellent catalytic activity of Pd/CeO2-Polyhedrons. Moreover, electronic reconstructed Pd0-O2−-Ce3+ active site limits the σ-bond rotation of half-hydrogenated intermediates through enhancing π backdonation and weakening the σ-bond, contributing to the reduction of trans products. Under mild conditions (30 °C, 0.3 MPa H2, and 2 h), Pd/CeO2-Polyhedrons catalyst shows exceptional methyl oleate selectivity of 52.6% with 93.8% conversion for sunflower oil hydrogenation. The catalyst has been further extended to the selective hydrogenation to several other vegetable oils such as sunflower oil, peanut oil, soybean oil, among others, under mild conditions.

Improved hydrogenation process for margarine production with no trans fatty acid formation by non-thermal plasma with needle-in-tube configuration

Non-thermal dielectric barrier discharge (DBD) plasma with needle-in-tube configuration was used to improve hydrogenation reaction for trans -fat free margarine production. Refined palm olein was used as raw material with operating conditions at ambient pressure, room temperature (29 °C) and no catalyst. Effects of hydrogen gas (H 2 ) concentration, input power, gas flow rate, discharge gap size and reaction time on fatty acid compositions and properties of hydrogenated refined palm olein after plasma treatment was evaluated. Lowest iodine value (IV) was achieved with reduction from 60.75 to 23.56 with increase in saturated fatty acid composition from 40.82 ± 0.05 to 68.70 ± 0.07% and decrease in unsaturated fatty acid composition from 59.11 ± 0.12 to 31.39 ± 0.01% under the condition of 0.5 L/min gas flow rate with 100% H 2 , 40 W input power, 0.5 cm gap size and 15 h reaction time. In addition, no trans -fat was detected by GC-MS analysis. Slip melting point (SMP) was increased from 9.33 ± 0.5 to 36.33 ± 0.5 °C. Acid value (AV) was reduced from 0.47 ± 0.02 to 0.32 ± 0.03 mg KOH/g oil. Texture of produced margarine was similar to that of commercial one. Generated hydrogen free radicals were hypothesized to perform hydrogenation by reacting with carbon-carbon double bonds (π-bonds), converting poly- and monounsaturated fatty acids into saturated ones. This highly effective catalyst-free plasma hydrogenation system can be used as alternative, environmentally friendly and economically feasible method to produce trans -fat free margarine. • Production of trans -fat free margarine via non-thermal plasma hydrogenation of palm olein. • Highly environmental-friendly, requiring no catalyst under low temperature and pressure. • Reduced acid value provides increased storage time and longer shelf life.

Lawrence La Fountain-Stokes, Translocas: The Politics of Puerto Rican Drag and Trans Performance

Translocas: The Politics of Puerto Rican Drag and Trans Performance examines the creative works, aesthetic practices, and lives of gender-nonconforming people, filling an important void in trans studies. Documenting the creative knowledge production of trans and drag performers produces a much-needed living archive that has been historically suppressed and erased.

YfeX - A New Platform for Carbene Transferase Development with High Intrinsic Reactivity.

Carbene transfer biocatalysis has evolved from basic science to an area with vast potential for the development of new industrial processes. In this study, we show that YfeX, naturally a peroxidase, has great potential for the development of new carbene transferases, due to its high intrinsic reactivity, especially for the N-H insertion reaction of aromatic and aliphatic primary and secondary amines. YfeX shows high stability against organic solvents (methanol and DMSO), greatly improving turnover of hydrophobic substrates. Interestingly, in styrene cyclopropanation, WT YfeX naturally shows high enantioselectivity, generating the trans product with 87 % selectivity for the (R,R) enantiomer. WT YfeX also catalyzes the Si-H insertion efficiently. Steric effects in the active site were further explored using the R232A variant. Quantum Mechanics/Molecular Mechanics (QM/MM) calculations reveal details on the mechanism of Si-H insertion. YfeX, and potentially other peroxidases, are exciting new targets for the development of improved carbene transferases.

Highly exo selective, photochemically promoted cyclization of iodoallene derivatives

AbstractA photochemically promoted intramolecular cyclization of aryl‐, vinyl‐, and alkyliodo allenes has been developed. The optimal conditions employed [Ir(ppy)2(dtbbpy)]PF6 (1 mol%) as catalyst affording products with high exo selectivity in moderate to good yields. Chiral substrates showed diastereoselectivity of up to 95/5 favoring trans product.

Diastereoselective Bidirectional C(sp3)−H Bond Functionalization of Piperazine Compounds

AbstractA highly diastereoselective bidirectional C(sp3)−H bond functionalization of piperazine compounds, triggered by a Lewis acid catalyzed sequential hydride shift/cyclization process, is reported. Catalysts and ligands are key factors that control the diastereoselectivity of the reaction. The reaction affords the product with good yield and high diastereoselectivity. Detailed investigation of the reaction mechanism reveals that the energy barrier between the cis products and trans products results in the diastereoselectivity of the reaction. The trans products, which have higher energy and which are generated from the cis products, act as intermediate products.magnified image

Ti-Catalyzed Reductive Dehydroxylative Vinylation of Tertiary Alcohols

Metal-catalyzed direct deoxygenative C(sp3)–C(sp2) coupling of alcohols is synthetically appealing, but it remains a particular challenge for the synthetic community. Herein, we demonstrate a radical dehydroxylative vinylation reaction of tertiary alcohols by Ti catalysis and, thus, establish a method for the construction of vinylated all-carbon quaternary centers. The reaction proceeds under mild conditions and tolerates various functionalities, including Ar–Bpin, Ar–SiMe3, alkyl chloride, phenol, nitrile, ester, furan, and thiophene. The reaction works with various vinyl halides, including fluorides, chlorides, bromides, and iodides. The use of a mixture of trans- and cis-haloalkenes gives the same trans products. The selectivity profiles were investigated among the vinyl and aryl electrophiles and among the different classes of alcohols.

H-D exchange and cis-to-trans isomerization over atomically dispersed Pd1/Cu2O and Pd1/Cu3N

Cis -to- trans isomerization is important for the production of trans -alkenes and derivatives. In this issue of Chem Catalysis , Zheng et al. report that atomically dispersed Pd catalysts are effective for heterolytic dissociation of H 2 into H δ+ and H δ− , yielding excellent selectivity for both hydrogen-mediated isomerization and H-D exchange of alkenes. Cis -to- trans isomerization is important for the production of trans -alkenes and derivatives. In this issue of Chem Catalysis , Zheng et al. report that atomically dispersed Pd catalysts are effective for heterolytic dissociation of H 2 into H δ+ and H δ− , yielding excellent selectivity for both hydrogen-mediated isomerization and H-D exchange of alkenes.

Synthesis of pyrano[3,2-c]quinoline derivatives using catalyst prepared from L-proline and p-toluenesulfonic acid

This research prepared new generation of ionic liquid (Deep eutectic solvent, DES) from L-proline and p-toluenesulfonic acid. The ionic liquid has an asymmetric center in its structure because the original amino acid has an asymmetric center. Subsequently, the ionic liquid was studied catalytic activity in reactions of quinoline[3,2-c]pyrano derivatives synthesis. Conditions affecting the reaction and rate of the two products were also investigated. The results of the reaction conditions showed that aprotic polar solvents gave better yields and the best reaction conditions were: temperature: 50oC, time: 2 h, catalytic amount: 35% mol . The ratios of two product isomers showed that the reaction always forms a mixture of two diastereomers and the trans products were synthesized with moderate enantiomeric excess (40% for four derivatives) compared with the cis products. In addition, the results on catalytic reuse also showed that the catalyst had good usability without significant decreasing activity. When benzaldehyde and aniline were changed with their derivates bearing donating electron group (-CH3), the reaction yields slightly decrease. However, benzaldehyde bearing withdrawing electron group (-F) gave moderate yield.

Photocatalyzed Dual-Oxidative Trifluoromethylthio-Trifluoromethylation of Alkenes with CF 3 SO 2 Na

A novel photocatalyzed trifluoromethylthio-trifluoromethylation of alkenes has been developed, using CF3SO2Na as both CF3 and SCF3 source. This photocatalyzed dual-oxidative strategy, which combine...

Hydrogenation of Cyclic 1,3-Diones to Their 1,3-Diols Using Heterogeneous Catalysts: Toward a Facile, Robust, Scalable, and Potentially Bio-Based Route.

Cyclopentane-1,3-diol (4b) has gained renewed attention as a potential building block for polymers and fuels because its synthesis from hemicellulose-derived 4-hydroxycyclopent-2-enone (3) was recently disclosed. However, cyclopentane-1,3-dione (4), which is a constitutional isomer of 3, possesses a higher chemical stability and can therefore afford higher carbon mass balances and higher yields of 4b in the hydrogenation reaction under more concentrated conditions. In this work, the hydrogenation of 4 into 4b over a commercial Ru/C catalyst was systematically investigated on a bench scale through kinetic studies and variation of reaction conditions. Herein, the temperature, H2-pressure, and the solvent choice were found to have significant effects on the reaction rate and suppression of undesired dehydration of 4. The cis–trans ratio of 4b is naturally generated as 7:3 in these reactions. However, at elevated reaction temperatures, 4b epimerizes, yielding more trans products. This effect was also studied and rationalized from a thermodynamic perspective using DFT. The combined optimized reaction conditions provided 78% yield for 4b, and successful applications to 8-fold scaled up reactions (40 g) and a substrate scope of several 1,3-diones demonstrate the general applicability of this catalytic approach.

Effect of AlEt2Cl on the polymerization of isoprene using TiCl4/MgCl2 type Ziegler-Natta catalyst: A DFT study

• The interaction between AlEt 2 Cl and MgCl 2 support was studied by the counterpoise corrected approach. • The mechanism of the polymerization of isoprene with heterogeneous Ziegler-Natta catalyst was first investigated by DFT. • The presence of AlEt 2 Cl improved the stereoselectivity of the active center. Alkylaluminium is one of the components of the Ziegler-Natta catalysts, which plays a significant role in the active materials with different regions and stereoselectivity. The polymerization of isoprene with alkylaluminium in TiCl 4 /MgCl 2 type Ziegler-Natta catalysts system is rarely studied by simulation. In this work, density functional theory (DFT) was applied to investigate the mechanism of the polymerization of isoprene with heterogeneous Ziegler-Natta catalyst in the presence and absence of AlEt 2 Cl on the surface of MgCl 2 (110). The interaction between AlEt 2 Cl and MgCl 2 support was studied by the counterpoise corrected approach. Two active models were adopted to analyze the influence of AlEt 2 Cl on the polymerization of isoprene in the coordination process and the insertion process respectively. The calculations indicated that only one double bond of isoprene was coordinated to the active center, the presence of AlEt 2 Cl improved the stereoselectivity of the active center, increased the difficulty of cis coordination, and reduced the difficulty of trans coordination. In the insertion process, the cis insertion process was more favorable and the trans product structure was more stable.

Photochemical and photophysical properties of cis-stilbene molecule by electronic structure calculations and nonadiabatic surface-hopping dynamics simulations

We combined the electronic structure calculations and OM2(orthogonalization model 2)/MRCI nonadiabatic surface-hopping dynamics simulations to scrutinize the photoisomerization mechanisms of cis-stilbene. The static electronic structure calculations showed that the irradiation of cis-stilbene populates the bright S1 state and we obtained three S1/S0 conical intersections (CIs) and proposed two nonadiabatic decay channels that efficiently de-excited to the ground state. In the first pathway, once excited to the S1 state, the cis-stilbene proceeds along S1 potential energy surface. Then, the molecule encounters S1S0-C CI, from which the system decays to S0 state. The other pathway involves the S1S0-D CI from where the S1 system hops to the ground state. In our simulations, we acquired cis, trans and DHP (4a,4b-dihydrophenanthrene) products and the ratio is estimated as 42:48:7. The present work show that the combination of electronic structure calculations and OM2/MRCI nonadiabatic dynamics can give detailed photochemical and photophysical information of stilbene systems.

Further Chemistry of Ruthenium Alkenyl Acetylide Complexes: Routes to Allenylidene Complexes via a Series of Electrophilic Addition Reactions

The methyl substituents in the cationic allenylidene complexes trans-[Ru{C═C═C(Me)R}Cl(dppe)2]OTf ([1a–f]OTf) are readily deprotonated to give the corresponding alkenyl acetylide complexes trans-[Ru{C≡CC(═CH2)R}Cl(dppe)2] (3; R = Me (a), Ph (b), cC5H10 (c), 4-MeS-C6H4 (d), cC4H3S (e), cC5H4N (f)). Similar chemistry is also observed from [Ru{C═C═C(Me)Ph}(dppe)Cp*]PF6 ([2b]PF6) and [Ru{C═C═C(Me)(4-MeS-C6H4)}(dppe)Cp*]PF6([2b]PF6), chosen to broaden the reaction scope, giving [Ru{C≡CC(═CH2)Ph}(dppe)Cp*] (4b) and [Ru{C≡CC(═CH2)(4-MeS-C6H4)}(dppe)Cp*] (4d). In turn, reactions of 3b,d and 4b,d with the [BF4]− salt of the electrophilic tritylium [CPh3]+ cation give the functionalized allenylidene complexes trans-[Ru{C═C═C(CH2CPh3)R}Cl(dppe)2]BF4 ([5b,d]BF4) and [Ru{C═C═C(CH2CPh3)R}(dppe)Cp*]BF4 ([6b,d]BF4) formed by addition of the electrophile to the remote vinylic carbon (C(δ)). Although trans-[Ru{C═C═C(CH2CPh3)Me}Cl(dppe)2]BF4 ([5a]BF4) could not be successfully purified from reactions of 3a with [CPh3]BF4, deprotonation of the crude product gave the Zaitsev vinyl product trans-[Ru{C≡CC(═CHCPh3)Me}Cl(dppe)2] (7a) in good yield. The initial cycloheptatrienyl adducts formed from reactions of 3b,d and 4b,d with the tropylium salt [C7H7]BF4 undergo a ring-contraction process in chloroform solutions upon exposure to air, to give the styrene-like products trans-[Ru{C═C═C(R)C(H)═CHPh}Cl(dppe)2]BF4 ([10b,d]BF4) and [Ru{C═C═C(R)C(H)═CHPh}(dppe)Cp*]BF4 ([11b,d]BF4), through what is believed to be a radical mechanism mediated by triplet oxygen.