Allylic Double Bond Research Articles

Synthesis and Characterization of Alkylamine-Functionalized Si(111) for Perovskite Adhesion With Minimal Interfacial Oxidation or Electronic Defects.

We investigated synthetic strategies for the functionalization of Si(111) surfaces with organic species containing amine moieties. We employed the functionalized surfaces to chemically "glue" perovskites to silicon with efficient electron transfer and minimal oxidation leading to deleterious recombination at the silicon substrate. A two-step halogenation-alkylation reaction produced a mixed allyl-methyl monolayer on Si(111). Subsequent reactions utilized multiple methods of brominating the allyl double bond including reaction with HBr in acetic acid, HBr in THF, and molecular bromine in dichloromethane. Reaction with ammonia in methanol effected conversion of the bromide to the amine. X-ray photoelectron spectroscopy (XPS) quantified chemical states and coverages, transient-microwave photoconductivity ascertained photogenerated carrier lifetimes, atomic force microscopy (AFM) quantified perovskite-silicon adhesion, and nonaqueous photoelectrochemistry explored solar-energy-conversion performance. The HBr bromination followed by the amination yielded a surface with ∼10% amine sites on the Si(111) with minimal oxide and surface recombination velocity values below 120 cm s-1, following extended exposures to air. Importantly, conversion of amine sites to ammonium and deposition of methylammonium lead halide via spin coating and annealing did not degrade carrier lifetimes. AFM experiments quantified adhesion between perovskite films and alkylammonium-functionalized or native-oxide silicon surfaces. Adhesion forces/interactions between the perovskite and the alkylammonium-functionalized films were comparable to the interaction between the perovskite and native-oxide silicon surface. Photoelectrochemistry of perovskite thin films on alkylammonium-functionalized n+-Si showed significantly higher Voc than n+-Si with a native oxide when in contact with a nonaqueous ferrocene+/0 redox couple. We discuss the present results in the context of utilizing molecular organic recognition to attach perovskites to silicon utilizing organic linkers so as to inexpensively modify silicon for future tandem-junction photovoltaics.

Hierarchical self-assembly from nanometric micelles to colloidal spherical superstructures

We report sequential self-assembly of low molecular weight asymmetric star-like polymers from nanometric spherical micelles (core diameter 8–12 nm) to colloidal spherical superstructures (d > 500–1000 nm) in aqueous media, as directed by quadruple hydrogen bonding moieties activated by solvent exchanges. The molecules consist of a rigid asymmetric steroidal cholic acid (CA) core, whose hydroxyl groups are first grafted with four oligomeric allyl glycidyl ether (AGE) chains involving six repeat units. The allylic double bonds are thiol-clicked with cysteamine (HS-(CH2)2-NH2), and in the final step their amino end groups are conjugated with 2-ureido-4[1H]-pyrimidinone (UPy) via isocyanate chemistry using UPy-(CH2)6-NCO to obtain asymmetric star-like facially amphiphilic molecules denoted as CA[(AGE-NH2)6]4-(UPy)n. They self-assemble into spherical micelles in dimethyl sulfoxide (DMSO), which suppresses the dimerization of UPys. Solvent exchange from DMSO to water activates the inter-micellar hydrogen bonds via the peripheral UPy units, which triggers the formation of spherical submicron to micron scale superstructures. Based on three-dimensional (3D) reconstruction using transmission electron tomography (ET), we show that such structures are composed of densely packed micellar network. Our work shows that surfactant-like molecules, characteristically leading to micelles, can undergo complex and hierarchical self-assembly to microscale by equipping the solubilising chains with hydrogen bonding units that can be switched ON and OFF by sequential solvent exchanges.

2,3-cis-Cyclization of 4-pentenoxyl radicals

4-Pentenoxyl radicals cyclize 2,3-cis-selectively, when substituted by an allylic hydroxy, acetyloxy, or benzoyloxy group. Additional substituents increase or decrease the fraction of 2,3-cis-cyclized product, depending on relative configuration, positioning, and their chemical nature. The preference for 3-acceptor-subsituted pentenoxyl radicals to furnish products of 2,3-cis-ring closure arises from a secondary orbital interaction between the allylic oxygen substituent and the alkene entity, kinetically disfavoring the 2,3-trans-mode of 5-exo-cyclization. Aligning the β-C,O-bond in anticline orientation to the plane of the alkene, which is the preferred conformation for transition structures for 2,3-trans-cyclization, stabilizes the double bond by delocalizing π-electrons into the σ*(C,O)-orbital. Along with energy decreases the affinity of π-electrons for forming a σ (C,O)-bond with the oxygen radical. In 2,3-cis-cyclization, a similar stabilizing effect cannot occur, because the allylic oxygen substituent and the alkene align synperiplanar. The kinetic effect of an allylic oxygen substituent becomes furthermore apparent in cyclization of the 3-hydroxynona-1,8-dien-5-oxyl radical, favoring intramolecular addition to the unsubstituted allylic double bond by a factor three.

A New Method of Preparing Gel for DGT Technique and Application to the Soil Phosphorus Availability Test

ABSTRACTThere are different methods for soil phosphorus (P) availability assessment. Researchers have recently introduced a new method called diffusive gradients in thin films (DGT) to evaluate P availability in soils. The aim of this study was manufacturing DGT gel using copolymerization of acrylamide and allylic double bonds agarose to replace the patented agarose as a cross-linker. We evaluated the efficacy of the prepared gel and used the assembled DGT with that gel in 10 calcareous soils. We compared the available P measured with the assembled DGT in those soils to Olsen’s P measured in the same soils. Corn plant (Zea mays L.) was also grown in those soils in a greenhouse for two months. Results showed that the diffusion coefficient of P ions in the gel with 0.3% of allylagarose at 25 °C was 6.9 * 10–6 cm2.s−1, implying that P ions were allowed to diffuse freely through the prepared diffusive gel. Measured P by the assembled DGT showed a close linear correlation (r2 = 0.98) with the P concentrations measured in soil solutions extracted by the Olsen method. This demonstrates the prepared allylagarose cross-linked gels’ efficiency and thus the reliability of the assembled DGT in easily and rapidly measuring the soil’s available P. The P, as measured by the assembled DGT in the examined soils, indicated a little lower correlation coefficient (r = 0.77) than those measured by the Olsen method (r = 0.88). However, the CE values measured by DGT showed a good correlation with P uptake by the roots (r = 0.88, p ≤ 0.01). The best correlation between CE and P content in corn occurred for the measurements made after 48 h of DGT placement in soils. The 20-h measurements had about the same r value, indicating that 20 h is sufficient for the placement of DGT assembly in the soil before its removing and measuring the available P. According to our findings, acrylamide—allylagarose gel as a diffusive gel in DGT was found to be suitable for P measurements in both aqueous solutions and soil.

ChemInform Abstract: Reactions of Tertiary Allylic Amines and Dichlorocarbenes.

AbstractThe reaction of tertiary allylic amines with intermediate dichlorocarbenes formed in situ from chloroform affords either formylamides via de‐N‐allylation or dichlorocyclopropane derivatives via addition of CCl2 to the allylic double bond.

Deviation from the anti-Markovnikov rule: a computational study of the regio- and stereoselectivity of diene hydroboration reactions

Hydroboration and subsequent use of boron compounds in novel organic synthesis have been flourishing in recent years largely due to its amiability in producing asymmetric stereo- and regioselective products. Direct products of diene hydroboration, however, have received little attention, with most substrates being assumed to produce the anti-Markovnikov product expected from textbook organic chemistry understanding. Previous experimental studies have observed the presence of a plethora of hydroboration products, and a significant progress has been made in assigning species to experimental data—though often with contradicting results. This study has used a computational approach employing quantum chemical calculations to determine atomic charges of cyclic and acyclic dienes and correlate these with calculated activation energy barriers in order to predict the regio- and stereoselective outcome of hydroboration reactions. Results indicated a strong correlation between the most polarized atomic charges of double-bonded carbons and the lowest energy transition states as expected. Intriguingly, we identified 1,3-cyclohexadiene as the main example that does not follow the anti-Markovnikov rule. We proceed to show that in addition to the polarity of the double bonds within a molecule, in this case, the conjugation with the allyl double bond and the specific geometric features of the cyclohexane ring were key stabilizing factors for the unexpected transition state preference, resulting in a regioselectivity that is in quantitative agreement with previous experimental data. Our results further indicated that Re-face attacks and steric factors due to substituents of the substrate influenced mainly the stereoselective outcome of the reaction, also affecting the pathways available to proceed through to complete the hydroboration process.

ChemInform Abstract: Regioselective Synthesis of Dihydrothiophene and Thiopyran Frameworks via Catalyst‐Controlled Intramolecular Cγ/Cδ—S Fusion of α‐Allyl‐β′‐oxodithioesters.

A highly efficient and atom-economic dual reaction manifold has been developed to synthesize 4H-thiopyran and 4,5-dihydrothiophene frameworks via regioselective intramolecular C–S fusion of α-allyl-β′-oxodithioesters. The ring size of the sulfur-heterocycles has been efficiently tuned by the use of two different catalytic systems. Palladium activates the Cδ–H of the allyl termini and facilitates the intramolecular Cδ–S coupling to furnish six-membered thiopyran skeletons exclusively. Conversely, the allylic double bond of the same substrate has been activated by BF3·Et2O to promote the Cγ–S cyclization leading to the formation of a five-membered dihydrothiophene nucleus.

Regioselective synthesis of dihydrothiophene and thiopyran frameworks via catalyst-controlled intramolecular Cγ/Cδ-S fusion of α-allyl-β'-oxodithioesters.

A highly efficient and atom-economic dual reaction manifold has been developed to synthesize 4H-thiopyran and 4,5-dihydrothiophene frameworks via regioselective intramolecular C-S fusion of α-allyl-β'-oxodithioesters. The ring size of the sulfur-heterocycles has been efficiently tuned by the use of two different catalytic systems. Palladium activates the Cδ-H of the allyl termini and facilitates the intramolecular Cδ-S coupling to furnish six-membered thiopyran skeletons exclusively. Conversely, the allylic double bond of the same substrate has been activated by BF3·Et2O to promote the Cγ-S cyclization leading to the formation of a five-membered dihydrothiophene nucleus.

Two new platinum complexes containing a chelating safrole-derivative and amine

A series of new platinum(II) complexes containing chelating safrole (or its derivatives) and various amines have been synthesized to evaluate their anticancer activity. Here we report the structure determination of [Pt((MeO)2Ph)(o-toluidine)Cl] (1) and [Pt((MeO)2Ph)(piperidine)Cl] (2), with (MeO)2Ph 3,4-dimethoxyphenyl-2-propene. Plate-like crystals of (1), suitable for x-ray diffraction measurement were obtained by slow evaporation from an ethanol solution. Rod-like crystals of (2) were harvested from ethanol after slow evaporation of acetone from an ethanol-acetone solution. Diffraction data were collected on a diffractometer equipped with a Bruker-AXS SMART 6000 CCD detector and integrated by the program SAINT. A multi-scan absorption correction was performed by the program SADABS. Both structures were solved by direct methods using the SHELXS program and refined according to the least-squares method to R-values of for 0.0204 (1) and 0.0280 for (2). The crystal of (1) to the orthorhombic space group P212121 and that of (2) belongs to the triclinic space group P-1. The asymmetric unit of (1) comprises one molecule of [Pt((MeO)2Ph)(o-toluidine)Cl]. The asymmetric unit of (2) consists of one ethanol molecule and one [Pt((MeO)2Ph)(piperidine)Cl] molecule. Both structures are similar with respect to the configuration and geometry of the Pt complex. Considering the centroid Cg of the allyl C=C bond as one ligand, the coordination geometry of Pt is square planar (other ligands are Cl, N (amine) and C (phenyl ring)). The angle between the best planes through the (MeO)2Ph and amine ligands is 84.3(1)0in (1) and 25.2(5)0in (2). The best plane through the allyl group makes an angle of 55.6(2)0and 56.4(4)0with the best plane through the (MeO)2Ph group, respectively in (1) and (2). The allyl double bond C=C is nearly perpendicular to Pt–Cg line, 89.8(2)0in (1) and 87.4(8)0in (2). For (1) the packing is essentially the result of van der Waals' interactions and two weak hydrogen bonds of type C-H...Cl and C-H...O. In (2) the packing is determined by the O-H...O hydrogen bond (O...O distance 2.870(4) Å) between ethanol and one of the methoxy substituents.

ChemInform Abstract: Broensted Acid Catalyzed Enantioselective Indole Aza‐Claisen Rearrangement Mediated by an Arene CH—O Interaction.

AbstractThe reaction tolerates a wide range of aromatic and heteroaromatic substituents at the allylic double bond and affords the products with high yields and enantioselectivities [cf.

Synthesis of Allyl-Functionalized Polymers via Selective Reversible Addition-Fragmentation Chain Transfer (RAFT) Polymerization

Allyl-functionalized copolymers with well-defined structure have been successfully prepared via selective reversible addition-fragmentation chain transfer (RAFT) copolymerization of styrene and allyl methacrylate possessing a higher reactive methacrylate and a lower reactive allyl. By employing a fast RAFT equilibrium, the polymerization for AMA completely occurred in methacrylate double bonds, whereas allyl double bonds remained intact and were introduced into the side-chains. GPC and 1H NMR analyses have confirmed the high chain-end functionality of the resultant copolymer.

Ferrocene-Containing Multifunctional Polyethers: Monomer Sequence Monitoring via Quantitative 13C NMR Spectroscopy in Bulk

Ferrocenyl glycidyl ether (fcGE) and allyl glycidyl ether (AGE) are copolymerized via living anionic ring-opening polymerization to generate polyfunctional copolymers with molecular weights up to 40 300 g/mol and low molecular weight dispersities (Mw/Mn < 1.18). Copolymerizations were carried out in bulk at 100 °C and unexpectedly found to proceed without any isomerization of the allyl double bonds. The copolymerization behavior of fcGE and AGE was monitored by in situ quantitative 13C NMR kinetic measurements in bulk, evidencing the formation of random copolymers under these conditions, showing no gradient of comonomer incorporation. The redox-active behavior of the copolymers and homopolymers of fcGE was studied by cyclic voltammetry (CV). In order to demonstrate possible postmodification reactions, the random copolymers were modified with N-acetyl-l-cysteine methyl ester via a thiol–ene addition. All polymers have furthermore been characterized by 1H NMR spectroscopy, DOSY 1H NMR spectroscopy, size exc...

Chemistry of transition-metal complexes containing functionalized phosphines. Part 2. Cationic rhodium(I) complexes stabilized by hemilabile diallylphosphines

Cationic rhodium(I) complexes of the type [Rh(COD){κ3(P,C,C)-RP(CH2CHCH2)2}][BF4] (R=tBu 3a, Ph 3b, iPr2N 3c) have been synthesized starting from the chloro-bridged dimer [Rh2(μ-Cl)2(COD)2] and fully characterized by 31P{1H}, 1H and 13C{1H} NMR. X-ray diffraction analysis of 3a and 3c showed a square planar geometry around of the rhodium atom, with allyl-phosphine ligands in a chelating fashion due to coordination of only one of the allylic double bonds while the other allyl moiety is located away from the metal center. Crystals of 3c showed the presence of the two enantiomers in the asymmetric unit. In solution, a dynamic equilibrium of exchange between the two allylic double bonds was detected by low temperature NMR analysis. Hemilabile properties of diallylphosphine ligands have been demonstrated by ligand exchange reactions and the reversible displacement of coordinated allylic double bond by acetonitrile have been observed. DFT calculations have been performed to explain the order of reactivity on removing the acetonitrile ligand under high vacuum.

Synthesis and evaluation of antiproliferative activity of a novel series of hydroxychavicol analogs

We have recently demonstrated that hydroxychavicol is a major constituent and the most active biophenolic of Piper betel leaves with significant antiproliferative activity in the micro molar range. Herein we present the design, synthesis and evaluation of fifteen novel hydroxychavicol analogs with varying antiproliferative activities in cancer cell lines from two representative tissue types, namely, the prostate and cervix that show very encouraging results compared to the parent compounds. Our long range goal is to develop a structure–activity guided relationship to gain mechanistic insights into novel molecular targets of this class of bioactive molecules for rational drug development. Cytotoxicity-guided experimentation on these novel analogs yielded the following structural factors as the key activity regulators: 1) unlike the hydroxyl substituent at position-4, the position-3 hydroxyl is vital for enhanced activity 2) acetoxyl groups are dispensable for activity as corroborated earlier by others 3) allylic double bonds at 2′C–3′C serve to positively influence antiproliferative activity 4) long saturated side chains at 1′-position negatively regulate antiproliferative activity and 5) maneuvering position-4 with a benzyl group positively impacted the biological activity profile. Most amphiphilic compounds showed moderate to good therapeutic potential as expected on the basis of medicinal chemistry principles. Intriguingly, the most active compound with ten-fold higher activity than the parent molecule was realized by sheer serendipity to employ a silica gel based rearrangement that was further explored using nuclear magnetic resonance spectroscopy and density functional theory calculations. This is the first report to describe strategies for optimal synthesis of a novel series of 15 analogs based upon hydroxychavicol, a simple phytochemical of immense anticancer potential.

A novel one-pot synthesis of oxazolidinones through direct introduction of CO2 into allylamine derivatives

1,3-Oxazolindin-2-one derivatives were obtained for the first time through carboxylative cyclization of allylamines in the absence of any metal or base catalyst. An electron-withdrawing substituent on the allylic double bond is crucial for the reaction success. Allylamines react with CO2 in MeCN/MeOH mixture and in scCO2 giving satisfactory results.

Study of green epoxy resins derived from renewable cinnamic acid and dipentene: synthesis, curing and properties

An epoxy based on cinnamic acid (Cin-epoxy) and an anhydride curing agent based on dipentene were prepared. Both products are liquids of low viscosity at room temperature. For the synthesis of the epoxy, cinnamic acid was first converted to a diacid by reacting with maleic anhydride via Friedel–Crafts reaction, followed by allylation of the carboxylic groups and subsequent epoxidation of the allyl double bonds. The curing agent was the Diels–Alder adduct of dipentene and maleic anhydride (DPMA). The chemical structures of Cin-epoxy and DPMA were confirmed by 1H NMR, 13C NMR, FT-IR and ESI-MS. Non-isothermal curing of Cin-epoxy was studied using differential scanning calorimetry (DSC). In addition to DPMA, two commercial anhydrides were also used to cure Cin-epoxy and the curing reactivity and properties of cured resins were compared. Thermal mechanical properties and thermal stability of the cured epoxy resins were studied using dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA), respectively. Results showed that Cin-epoxy was slightly more reactive than the bisphenol A type epoxy DER 332 and displayed good dynamic mechanical properties and thermal stability.

Bisamino(diphosphonite) with dangling olefin functionalities: synthesis, metal chemistry and catalytic utility of Rhiand Pdiicomplexes in hydroformylation and Suzuki–Miyaura reactions

Bisamino(diphosphonite), p-C6H4{N{P(OC6H4C3H5-o)2}2}2 (1), was prepared by reacting p-C6H4{N(PCl2)2}2 with four equivalents of o-allylphenol in 85% yield. Compound 1 on treatment with [M(CO)4(HNC5H10)2] (M = Mo or W) gave cis-[{M(CO)4}2{p-C6H4{N(P(OC6H4C3H5-o)2)2}2}] (2, M = Mo; 3, M = W). The reaction of 1 with [Fe(η(5)-C5H5)(CO)2]2 yielded the complex [{Fe(η(5)-C5H5)(μ-CO)}2{p-C6H4{N(P(OC6H4C3H5-o)2)2}2}] (4). Treatment of 1 with Fe(CO)5 furnished a mononuclear complex, [{Fe(CO)3}2{p-C6H4{N{P(OC6H4C3H5-o)2}2}2}] (5). The ruthenium(II) complex, [{(η(6)-p-cymene)Ru(μ-Cl)3RuCl}2{p-C6H4{N(P(OC6H4C3H5-o)2)2}2}] (6), was obtained on treatment of ligand 1 with [(η(6)-p-cymene)Ru(Cl)2]2. The reaction between 1 and [Rh(COD)Cl]2 (COD = 1,5-cyclooctadiene) in dichloromethane resulted in the formation of a dinuclear complex [{RhCl}2{p-C6H4{N(P(OC6H4C3H5-o)2)2}2}] (7), in which the allyl double bond of one of the phenoxy groups coordinates to the metal center. When ligand 1 was reacted with two equivalents of [Pd(COD)Cl2], a dinuclear complex [{PdCl2}2{p-C6H4{N(P(OC6H4C3H5-o)2)2}2}] (8) was obtained. With copper(I) halides, ligand 1 afforded tetranuclear complexes, [{(Cu(μ-X)(NCCH3))2}2{p-C6H4{N(P(OC6H4C3H5-o)2)2}2}] (9, X = Cl; 10, X = Br; 11, X = I). Reaction of 1 with four equivalents of [AuCl(SMe2)] produced a tetranuclear complex, [(AuCl)4{p-C6H4{N{P(OC6H4C3H5-o)2}2}2}] (12). Complex 8 shows excellent catalytic activity in the Suzuki-Miyaura cross-coupling reaction under microwave conditions and complex 7 catalyzes hydroformylation of styrenes with good TONs.

A thiol‐ene clickable hyperbranched polyester via a simple single‐step melt trans‐esterification process

ABSTRACTSelf‐condensation of AB2 type monomers (containing one A‐type and two B‐type functional groups) generates hyperbranched (HB) polymers that carry numerous B‐type end‐groups at their molecular periphery; thus, development of synthetic methods that directly provide quantitatively transformable peripheral B groups would be of immense value as this would provide easy access to multiply functionalized HB systems. A readily accessible AB2 monomer, namely diallyl, 5‐(4‐hydroxybutoxy)isophthalate was synthesized, which on polymerization under standard melt‐transesterfication conditions yielded a peripherally clickable HB polyester in a single step; the allyl groups were quantitatively reacted with a variety of thiols using the facile photoinitiated “thiol‐ene” reaction to generate a wide range of derivatives, with varying solubility and thermal properties. Furthermore, it is shown that the peripheral allyl double bonds can also be readily epoxidized using meta‐chloroperoxybenzoic acid to yield interesting HB systems, which could potentially serve as a multifunctional cross‐linking agent in epoxy formulations. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40248.

4-HYDROXY-2-QUINOLONES. 202. SYNTHESIS, CHEMICAL AND BIOLOGICAL PROPERTIES OF 4-HYDROXY-6,7-DIMETHOXY-2-OXO-1,2-DIHYDROQUINOLINE-3-CARBOXYLIC ACID ALKYLAMIDES

In continuation of the search for potential analgesics amongst 4-hydroxyquinol-2-one derivatives we have proposed and carried out a preparative method of synthesis of 4-hydroxy-6,7-dimethoxy-2-oxo-1,2-dihydroquinoline-3-carboxylic acid alkylamides. It has been shown that bromination of 4-hydroxy-6,7-dimethoxy-2-oxo-1,2-dihydroquinoline-3-carboxylic acid allylamide using an equivalent of molecular bromine occurs with a conventional addition of the halogen to the allyl double bond and not with halocyclization. The results of the study of the analgesic properties of the compounds prepared are presented. Authors: I. V. Ukrainets, O. V. Bevz, E. V. Mospanova, L. V. Savchenkova, and S. I. Yankovich. English translation in Chemistry of Heterocyclic Compounds , 2012, 48 (2), pp 320-326 http://link.springer.com/article/10.1007/s10593-012-0992-4

Diastereoselective osmium-catalyzed vicinal oxyamination of acyclic allylic alcohol derivatives.

The osmium-catalyzed oxyamination of chiral acyclic allylic alcohol derivatives bearing mono- and 1,1-di-substituted double bonds with benzyl N-(4-tosyloxy)carbamate proceeds with high regioselectivity and moderate levels of diastereoselectivity favoring the anti product. The observed stereoselectivity shows a clear and systematic trend with anti:syn ratios increasing in line with the size of substituent at both the allylic stereocenter and double bond α-carbon. The stereoinduction is in accord with the sense of diastereoselectivity predicted by Kishi's empirical rule and a previously reported transition state model for the osmium-catalyzed dihydroxylation of allylic alcohol derivatives. In contrast, allylic alcohol derivatives bearing trisubstituted double bonds show low or no reactivity in the oxyamination reaction affording the syn product in low yield in the cases examined.