Allylic Derivatives Research Articles

Silica Support‐Enhanced Pd‐Catalyzed Allylation Using Allylic Alcohols

AbstractAlthough allylation using allylic alcohol is an environmentally‐friendly method because of water being the sole byproduct in such reactions, allylic alcohol is one of the most difficult allylating agents in Pd‐catalyzed allylation of nucleophiles. In this study, we successfully developed a mesoporous silica‐supported Pd complex as an efficient catalyst for the allylation of nucleophiles using allylic alcohols as allylating agents. The allylic alcohol is activated by the silanol group on the support surface, which easily undergoes a π‐allylpalladium intermediate formation. The catalytic activity of the supported Pd complex was ca. 9 times higher than that of its homogeneous precursor Pd complex. A highest turnover number of 4500 based on Pd was achieved. Various nucleophiles and allylic alcohol derivatives could be used as substrates. Not only the detailed catalyst structure but also the reaction mechanism including the concerted activation of allylic alcohol by the Pd complex and silanol were investigated by several spectroscopic techniques, such as Pd K‐edge XAFS, solid‐state NMR, and in‐situ FT‐IR measurements.

Flupirtine derivatives as potential treatment for the neuronal ceroid lipofuscinoses.

ObjectiveNeuronal Ceroid Lipofuscinoses (NCL) are fatal inherited neurodegenerative diseases with established neuronal cell death and increased ceramide levels in brain, hence, a need for disease‐modifying drug candidates, with potential to enhance growth, reduce apoptosis and lower ceramide in neuronal precursor PC12 cells and human NCL cell lines using enhanced flupirtine aromatic carbamate derivatives in vitro.MethodsAromatic carbamate derivatives were tested by establishing growth curves under pro‐apoptotic conditions and activity evaluated by trypan blue and JC‐1 staining, as well as a drop in pro‐apoptotic ceramide in neuronal precursor PC12 cells following siRNA knockdown of the CLN3 gene, and CLN1‐/CLN2‐/CLN3‐/CLN6‐/CLN8 patient‐derived lymphoblasts. Ceramide levels were determined in CLN1‐/CLN2‐/CLN3‐/CLN6‐/CLN8 patient‐derived lymphoblasts before and after treatment. Expression of BCL‐2, ceramide synthesis enzymes (CERS2/CERS6/SMPD1/DEGS2) and Caspases 3/8/9 levels were compared in treated versus untreated CLN3‐deficient PC12 cells by qRT‐PCR.ResultsRetigabine, the benzyl‐derivatized carbamate and an allyl carbamate derivative were neuroprotective in CLN3‐defective PC12 cells and rescued CLN1‐/CLN2‐/CLN3‐/CLN6‐/CLN8 patient‐derived lymphoblasts from diminished growth and accelerated apoptosis. All drugs decreased ceramide in CLN1‐/CLN2‐/CLN3‐/CLN6‐/CLN8 patient‐derived lymphoblasts. Increased BCL‐2 and decreased ceramide synthesis enzyme expression were established in CLN3‐derived PC12 cells treated with the benzyl and allyl carbamate derivatives. They down‐regulated Caspase 3/Caspase 8 expression. Caspase 9 expression was reduced by the benzyl‐derivatized carbamate.InterpretationThese findings establish that compounds analogous to flupirtine demonstrate anti‐apoptotic activity with potential for treatment of NCL disease and use of ceramide as a marker for these diseases.

Synthesis of 4,5-dihydroisoxazole derivatives of maleopimaric acid by 1,3-dipolar cycloaddition reaction between its allyl derivatives and aromatic nitrile oxides

While searching for pharmacologically active compounds among 4,5-dihydrooxazole derivatives of maleopimaric acid, we studied for the first time the reaction between allyl-substituted maleopimaric acid derivatives and aromatic nitrile oxides that were generated from oximes by oxidation with sodium hypochlorite with or without ultrasonication of the biphasic system. The reaction occurred under mild conditions and regiospecifically provided 4,5-dihydroisoxazol-5-ylmethyl derivatives of maleopimaric acid in 77–99% yields.

Synthesis of Bifunctional Allylic Compounds by Using Cyclopropenes as Functionalized Allyl Equivalents

The synthesis of uncommon bifunctional allylic derivatives bearing a silane and an alcohol within the same allylic framework is reported. This method relies on the coupling of hydrosilanes with substituted and functionalized cyclopropenes, which deliver the allyl fragment. Rhodium(II) catalysts provide regioselective access to vinyl carbene intermediates, which easily undergo Si-H bond insertions. The transformation occurs with complete atom economy and shows a remarkably broad scope, including a intramolecular version for the synthesis of cyclic O-Si-linked compounds as well as the synthesis of the corresponding allyl amines.

Synthesis of Bifunctional Allylic Compounds by Using Cyclopropenes as Functionalized Allyl Equivalents

AbstractThe synthesis of uncommon bifunctional allylic derivatives bearing a silane and an alcohol within the same allylic framework is reported. This method relies on the coupling of hydrosilanes with substituted and functionalized cyclopropenes, which deliver the allyl fragment. Rhodium(II) catalysts provide regioselective access to vinyl carbene intermediates, which easily undergo Si−H bond insertions. The transformation occurs with complete atom economy and shows a remarkably broad scope, including a intramolecular version for the synthesis of cyclic O−Si‐linked compounds as well as the synthesis of the corresponding allyl amines.

Facile transformation of 2H,3H-decafluoropentane (HFC-4310mee) into (Z)-2H-nonafluoropent-2-ene and its application to the synthesis of polyfluorinated homoallylic ketones by Claisen rearrangement

The dehydrofluorination of 2H,3H-decafluoropentane (HFC-4310mee) using 1,8-diazabicyclo[5.4.0]-7-undecene (DBU) selectively gave (Z)-2H-nonafluoropent-2-ene as a bench-stable volatile liquid. Nucleophilic substitution reactions of (Z)-2H-nonafluoropent-2-ene with allylic alcohols gave the corresponding polyfluorinated allylic vinyl ether derivatives. The Claisen rearrangement of the polyfluorinated allylic vinyl ethers smoothly proceeded under ambient conditions to give polyfluorinated homoallylic ketones quantitatively. These results indicate the potential of 2H,3H-decafluoropentane as an inexpensive and easy-to-handle chemical feedstock for the syntheses of densely functionalized polyfluorinated organic compounds.

Stereoselective Photooxidations by the Schenck Ene Reaction

Abstract150 years after the first report of an organic reaction with singlet oxygen (1O2) and 70 years after the discovery of the singlet oxygen‐ene reaction (Schenck reaction) with alkenes, this allylic photooxidation has matured to a powerful transformation that enables access to diverse sets of allyl alcohol derivatives from ubiquitous starting materials. The reaction exhibits high sustainability (100 % atom economy, use of simple alkenes, air, metal‐free catalyst and visible light). Good levels of chemo‐, regio‐, and stereocontrol were observed in the synthesis of various fine chemical building blocks and biologically active molecules. This Minireview provides an overview of the key strategies that enable stereoselective oxygen‐ene reactions in the context of complex molecule syntheses including photo‐oxygenations of functionalized alkenes, cycloalkenes, and auxiliary‐based methods.

Synthesis of Tetrasubstituted Alkenes by Tandem Metallacycle Formation/Cross-Electrophile Coupling.

Nickel-catalyzed cross-electrophile couplings have recently emerged as highly effective and practical methods for the formation of C-C bonds. By merging this process with well-established π-π coupling chemistry, a new method for the synthesis of tetrasubstituted alkenes has been developed. The procedure relies on the use of chlorosilanes as a means of generating reactive vinylnickel intermediates, which are capable of undergoing a reductive cross-electrophile coupling with alkyl halides. The method not only generates highly substituted allylic alcohol derivatives but also obviates the need for stoichiometric organometallic nucleophiles and provides greatly improved scope and functional group tolerance compared with previously developed methods.

One-pot Preparation and Characterisation of Five-membered Cyclic Alcohols

Background: Over the last few years, one of the primary focuses of our research group has been the synthesis and biological evaluation CANs featuring structural and/or configurationally alterations on the carbocyclic moiety. We previously reported an enlarged group of diversely functionalized amino cyclopentenols, cyclopentenols and cyclopentenones as useful precursors in the synthesis and pos-terior biological evaluation of CANs featuring structural and/or configurationally alterations on the carbo-cyclic moiety; moreover the five-membered carbocycles are common structural units in other natural products and bioactive compounds, for this reason, these compounds presented great interest for their use as building blocks in the development of compounds with potential pharmacological activities. Method: The conversion of benzyl cyclopent-3-enocarboxylate into a mixture of the corresponding hydroxy allylic esters 5a and 5b was efficiently achieved by the employed diphenyl diselenide, H2O2 in dry CH2Cl2 for the synthesis of phenylselenenic acid and electrophilic addition to double bond of 3, and 90% tert-butyl hydroperoxide subsequently being added. Results: The mixture of compounds 5 was obtained in good yields under these conditions, and this was readily separated by column chromatography. Isolated components were identified by1H and13C NMR spectral, as well as by its EI HRMS. The corresponding alcohols 5a or 5b were easily transformed in the corresponding 3,5-dinitrobenzoyl derivatives, 6a and 6b, from which single crystals were obtained, permitting unequivocal identification. Conclusion: Using a one-pot method, benzyl cyclopent-3-enecarboxylate was turned into a mixture of corresponding hydroxy allylic derivatives 5a and 5b, employing diphenyl diselenide, H2O2 and tert-butyl hydroperoxide for the formation and subsequent oxidation/elimination of the first-generated alkyl phenyl selenides. The use of these oxidants corresponds to modern trends in organic synthesis, because they are easily available and environmentally friendly reagents, which can be used at a large scale.

Rhodium-Catalyzed Enantioselective Alkenylation of Cyclic Ketimines: Synthesis of Multifunctional Chiral α,α-Disubstituted Allylic Amine Derivatives.

By employing a simple open-chain chiral phosphite-olefin ligand, a highly enantioselective rhodium-catalyzed alkenylation of 1,2,5-thiadiazole 1,1-dioxide-type cyclic ketimines with diverse vinylboronic acids was achieved under mild conditions at room temperature. This protocol provides an efficient and practical access to multifunctional α,α-disubstituted chiral allylic amines bearing quaternary stereocenters in high yields (up to 99%) with good to excellent ee's (up to 99%).

α-Substituted Benzylic Complexes of Palladium(II) as Precursors of Palladium Hydrides

The adoption of a pseudoallylic (η3) form makes palladium benzylic derivatives a class of stabilized palladium alkyls that can undergo β-H elimination reactions in a more controlled way. α-(Pentafluorophenylmethyl)benzyl palladium complexes have been studied, and they decompose by β-H elimination to give palladium hydrides that, depending on the auxiliary ligands, can: (a) transmetalate to another palladium atom and, by reductive elimination, give hydrogenated products; this process is favored for a combination of bridging ligands (i.e., halogens) and low coordinating ligands. (b) Be used as a hydride source and get trapped by a diene to give palladium allylic derivatives. The presence of carbon monoxide does not induce a β-H elimination reaction, and only CO insertion into the Pd–benzyl bond to give acyl derivatives is observed.

Determination of Inhibition Properties of Caffeine, Theophylline and Their Allylic and Propargylic Derivatives on API 5L X70 Steel Immerse in 1M HCl

The determination of the inhibitory properties of caffeine and theophylline and their allylic and propargylic derivatives as inhibitors of corrosion was developed for API 5L X70 steel immerse in 1M HCl by means of the electrochemical impedance technique. It was found that caffeine and its derivative propargylic show good inhibition efficiency 91% at 5 and 20 ppm respectively. Furthermore, it is also shown that while caffeine and propargyl-theophylline were adsorbed on the steel surface trough a chemisorption process, theophylline and allyl-theophylline follow a combined adsorption process.

Silane coupling and mordanting as attachment techniques for pyridylazo and thiazolylazo ligands in the synthesis of adsorbents for uranium in seawater

Activated carbon adsorbents modified with azo compounds (4-(2-pyridylazo)resorcinol, 1-(2-pyridylazo)-2-naphthol, 4-(2-thiazolylazo)resorcinol), or with allyl and vinylbenzyl derivatives of 4-(2-thiazolylazo)resorcinol, were observed to be highly effective in removing uranium from seawater and providing high loadings. Adsorbents consisting of azo compounds attached to fiber fabrics were prepared using silane coupling to attach azo reagents to silica fibers or mordanting agents such as tannic acid or aluminum acetate to attach them to cellulose fibers. Loadings of 15–45 mg U g−1 adsorbent were obtained. Scanning electron microscopy/energy dispersive X-ray spectroscopy measurements confirmed the presence of high concentrations of uranium on the surface of the silica-based and cellulose-based fibers.

SYNTHESIS OF ORGANOSILICON COMPOUNDS FOR DRESSING OF NANOCOMPOSITES ON BASIS OF QUARTZ AND HIGH DENSITY POLYETHYLENE

The method of synthesis of epoxy compounds containing silicon on basis of hydrosilylation reaction of allyl derivatives of glycidyl ethers with methyl diethyl silane in the presence of platinum-hydrochloric acid was developed. It was determined that these silanes enter into the reaction with various agents bound with oxirane ring by forming corresponding derivatives of organosilicon compounds. Twelve synthesized organosilicon compounds were used as coupling agents for quartz nanoparticles. It was determined that synthesized organosilicon compounds have good coupling agents promoting improvement of compatibility of mineral filler with polymeric matrix. Quartz nanoparticles (up to 100 nanometers) were used as mineral filler. Nanoparticles quartz received on analytical mill А-11 at speed of rotation of a rotor of 28000 turn/min. The dimension of nanoparticles was defined on the device of model STA PT1600 Linseiz Germany and compounded 20-100 nm. For research of physical-mechanical properties of the polymerous nano composites they subjected to pressing at temperature of 190-200 °С. From the pressed plates samples for definition of breaking stress, specific elongation, flexural strength of the filled composites cut down. Research results of influence of type and concentration of coupling agent and filler upon main physical-mechanical properties of nanocomposites are given. Dressing nanoparticles carried out in 0.5 - 2.0 % water solution of the silicoorganic compound acidified by acetic acid to рН = 3.5, at temperature of 55 °С in flow during 60 min. Optimal concentrations of coupling agents and filler, which provide maximal values of composites physical-mechanical properties, were determined. Main reasons providing improvement of strength properties of finished nanocomposites were revealed. The comparative analysis of the data obtained shows that rather high physical-mechanical properties possess nanocomposites in which as dressing 2-metil-5-metildietylsilil-2- (methylenoxy-1,3-dioxosolano) – pentane was used.Forcitation:Gurbanova R.V., Kakhramanov N.T., Shatirova М.I., Мuzafarov А.М., Kahramanly Yu.N., Mammadli U.M. Synthesis of organosilicon compounds for dressing of nanocomposites on basis of quartz and high density polyethylene. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 2. P. 65-72

Cationic R‐Substituted‐Indenyl Nickel(II) Complexes of Arsine and Stibine Ligands: Synthesis, Characterization, and Catalytic Behavior in the Oligomerization of Styrene

A series of new cationic Rn‐substituted‐indenyl nickel(II) complexes containing arsine or stibine ligands were synthesized in moderate to very high yields by the protonation of the corresponding bis(indenyl) nickel derivatives [Ni(η‐Rn‐Ind)2] with HBF4, in the presence of 2 equiv. of AsPh3 or SbPh3 donor ligands. These complexes, with the general formula [Ni(η‐Rn‐Ind)(EPh3)2]BF4 (E = As, Sb), were structurally characterized by NMR spectroscopy and X‐ray diffraction, and subsequently tested as single‐component catalysts for the oligomerization of styrene, leading to the formation of very low molecular weight head‐to‐tail oligomers (typically consisting of dimers, trimers and tetramers). The new 1‐ or 2‐monosubstituted‐indenyl NiII catalyst precursors exhibit extremely high catalytic activities, considerably higher than those observed for the symmetrical unsubstituted‐ and the 1,3‐disubstituted‐indenyl nickel analogues (i.e. monosubstituted >> non‐substituted > 1,3‐disubstituted), their reactivity pattern showing similarities with that of the corresponding allyl derivatives. A simpler and more straightforward experimental procedure for the high yield preparation of [NiBr2(DME)], an important nickel starting material, which was used in the preparation of the bis(indenyl) nickel precursors of this work, is also described.

Thorium(iv) alkyl and allyl complexes of a rigid NON-donor pincer ligand with flanking 1-adamantyl substituents.

Palladium-catalyzed coupling of 1-adamantylamine (2 equiv.) with 4,5-dibromo-2,7-di-tert-butyl-9,9-dimethylxanthene afforded the proligand 4,5-bis(1-adamantylamino)-2,7-di-tert-butyl-9,9-dimethylxanthene, H2[XAd] (1), which upon deprotonation with excess KH or KCH2Ph in THF or dme generated [{K(THF)3}2(XAd)] (2a) and [K2(XAd)(dme)] (2b). Subsequent reaction of in situ generated 2a or 2b with [ThCl4(dme)2] yielded [(XAd)ThCl4K2]·x(dme) (3; x = 0.5-2), which reacted with 2 equiv. of LiCH2SiMe3 or K[allylTMS] to afford the bis(hydrocarbyl) complexes [(XAd)Th(CH2SiMe3)2(THF)] (4) and [(XAd)Th(η3-allylTMS)2] {5; allylTMS = 1-(SiMe3)C3H4}. Dialkyl complex 4 was stable at 80 °C for at least 2.5 hours, but decomposed over 4.5 hours at 110 °C. Diallyl complex 5 was stable for hours at 85 °C, and suffered less than 5% decomposition after 10 minutes at 155 °C. At room temperature, averaging of the syn and anti protons of the allyl CH2 groups of 5 occurred on the NMR timescale, as a consequence of rapid π-σ-π hapticity changes. Additionally, low temperature 1H and 13C NMR spectroscopy indicates that 5 exists as a rapidly exchanging mixture of two isomers with C1 and C2 symmetry. Compounds 2a, 4 and 5 were crystallographically characterized.

Palladium-catalyzed regioselective hydroboration of aryl alkenes with B2pin2.

A palladium(ii)-catalyzed hydroboration of aryl alkenes with stable and easy-to-handle (pinacolato)diboron (B2pin2) under mild conditions has been developed. Acetic acid acted as the solvent and the hydrogen source, which has been identified by deuterium experiments. Notably, isomerization-hydroboration of allyl benzene derivatives was observed. As a result, a series of benzyl boronic esters were obtained in moderate to excellent yields with exclusive regioselectivity.

Asymmetric synthesis via stereospecific C-N and C-O bond activation of alkyl amine and alcohol derivatives.

This perspective showcases our development of benzylic and allylic amine and alcohol derivatives as electrophiles for stereospecific, nickel-catalyzed cross-coupling reactions, as well as the prior art that inspired our efforts. The success of our effort has relied on the use of benzyl ammonium triflates as electrophiles for cross-couplings via C-N bond activation and benzylic and allylic carboxylates for cross-couplings via C-O bond activation. Our work, along with others' exciting discoveries, has demonstrated the potential of stereospecific, nickel-catalyzed cross-couplings of alkyl electrophiles in asymmetric synthesis, and enables efficient generation of both tertiary and quaternary stereocenters.

Synthesis and crystal structure of copper (I) sulfamate π-complex with 5-methyl-N-(Allyl)-1,3,4-thiadiazol-2-amine of [Cu2(C6H10N3S2)2(NH2SO3)2] composition

[Cu 2 ( Mepeta ) 2 (NH 2 SO 3 ) 2 ] compound has been obtained by means of alternating current electrochemical technique starting from the mixture of propanolic solution of 5-methyl- N -(allyl)-1,3,4-thiadiazol-2-amine ( Mepeta ) and water solution of Cu(NH 2 SO 3 ) 2 ·xH 2 Oand later X-ray structurally characterized by single crystal method. High-quality crystals of the compound appeared in three days. The compound crystallizes in the triclinic system: Sp. gr. – P -1, a = 7.799(2), b = 8.054(3), c = 10.165(2) Å, α = 96.003(7), β = 109.17 (3), γ = 112.95(3)°, V = 535.2 (3) Å 3 ,Z = 1, D х = 1.954(3) g/sm 3 , R ( F ) = 0.056 for 2052 independent reflections with F ≥ 4 σ ( F ). In the structure 1 , organic molecule Mepeta acts as chelate-bridging tridentate ligand being connected to copper (I) by two N atoms of thiadiazo leringand (C=C)-bond fromallyl-group, resulting in a formation of stable cationic dimers [Cu 2 ( Mepeta ) 2 ] 2+ . In the structure 1 , N atom from sulfamate-anion occupies an apical position of the metal coordination polyhedron. The efficiency of Cu(I)-(C=C) interaction is confirmed by the fact that allylic C=C bond is slightly elongated to 1.355(7) Å. Selected bond length (in Å) and angle (in deg) values: Cu1–N3 2.092(3), Cu1–N4 i 1.998(4), Cu1–N1 2.267(4), Cu–m 1.965(4) (m –middle point of C7=C8 bond), C8–C9 1.355(7), N4 i –Cu1–N3 112.8(3), N4 i –Cu1–N1 95.5(4), N4 i –Cu1– m 130.5(2), N3–Cu1–N1 86.5(3), N3–Cu1– m 109.6(3). Despite the presence of sulfamate anion NH 2 SO 3 – N-atom, thiadiazole ligand participates in the formation of stable tectone [Cu 2 ( L ) 2 ] 2+ previously found in the structures of other Сu(I) π-complexes with allyl derivatives of 1,3,4-thiadiazole. Hydrogen bonds N-H···O play an additional stabilizing role in the formation of hydrogen-bonded chains. Keywords : copper (I), sulfamate anion, π-complex, 1,3,4-thiadiazole, crystal structure.

Palladium triggered diene formation from nitro allylic compounds: a versatile entry into naphthalene derivatives.

Nitro allylic derivatives were converted into dienes through the elimination of the nitro group under basic treatment, in the presence of a palladium catalyst. This reaction probably involves the formation of a palladium π-allyl complex followed by a base-promoted β-hydride elimination. This reaction, combined with the condensation of ketones with nitromethane and the functionalization of the resulting nitrocycloalkenes, constitutes a very powerful synthetic tool for the formation of dienes. Particular attention has been brought to the application of this methodology to the formation of 1-substituted naphthalenes from 1-tetralone.