Allyl Bromide Research Articles

Enhancement of mechanical properties of natural rubber latex sheets by incorporating allyl-modified microcrystalline cellulose (AMCC)

Microcrystalline cellulose (MCC) was chemically modified with allyl bromide through the hydroxyl groups of cellulose to obtain allyl-modified microcrystalline cellulose (AMCC). To enhance the curing and mechanical properties of natural rubber latex, this AMCC was then compounded with a natural rubber latex formulation to produce rubber sheets. Unmodified MCC was also compounded and prepared into rubber sheets, which served as a reference. The formation of AMCC was confirmed using Fourier Transform Spectroscopy (FTIR). Furthermore, the thermal behavior of AMCC was examined by thermogravimetric analysis (TGA), and the degree of crystallinity before and after modification was evaluated by X-ray diffraction (XRD). The results of the rubber sheets showed that overall, maximum torque (MH), degree of crosslinking density, vulcanization rate (cure rate index), and tensile strength increased in AMCC-loaded rubber compared to MCC-loaded sheets. On the other hand, optimum cure time (t90) and elongation at break were lower in the AMCC-loaded rubber than in the MCC-loaded sheets. In overall, this method outlines a successful incorporation of modified cellulose into natural rubber-based products to obtain enhanced mechanical properties.

Asymmetric Synthesis of Dialkyl Carbinols by Ni-Catalyzed Reductive-Oxidative Relay of Distinct Alkenes.

Enantioenriched unsymmetric dialkyl carbinol derivatives are of importance in natural products, bioactive molecules, and functional organic materials. However, the catalytic asymmetric synthesis of dialkyl carbinol derivatives remains challenging due to the similar steric and electronic properties of two alkyl substituents. Herein, an unprecedented synthesis of chiral dialkyl carbinol ester derivatives from Ni-catalyzed reductive-oxidative relay cross-coupling of two alkenes is developed for the first time. The reaction features the use of enol esters and unactivated alkenes as two different alkyl equivalents to undergo head-to-tail and enantioselective alkyl-alkyl cross-coupling. The reaction undergoes two-electron reduction and single electron oxidation in the presence of both reductants and oxidants. The use of an allyl bromide as single electron acceptor is crucial for the success of this non-trivial asymmetric cross-coupling, providing a new reaction mode for asymmetric alkyl-alkyl bond-forming event in the absence of stoichiometric alkyl electrophiles.

Optimization of Palladium-Catalyzed One-Pot Synthesis of Functionalized Furans for High-Yield Production: A Study of Catalytic and Reaction Parameters

This study investigates the palladium-catalyzed one-pot synthesis of functionalized furans from 1,3-Dicarbonyl compounds and alkenyl bromides, focusing on various catalysts and reaction parameters. Different catalysts, including PdCl₂(CH₃CN)₂, Pd(OAc)₂, and Pd(acac)2 as well as solvents, bases, and oxidants, were systematically evaluated. PdCl₂(CH₃CN)₂ emerged as the most effective catalyst, achieving a remarkable yield of 94%. Optimal reaction conditions were identified as PdCl₂(CH₃CN)₂ in dioxane at 80 °C with K₂CO₃ as the base and CuCl₂ as the oxidant. This study also explored various 1,3-diketones including Cyclohexane-1,3-dione, 5,5-Dimethylcyclohexane-1,3-dione, 2H-Pyran-3,5(4H,6H)-dione, Cyclopentane-1,3-dione, Pentane-2,4-dione, Ethyl 3-oxobutanoate, 1,3-Diphenylpropane-1,3-dione, 1,3-Dip-tolylpropane-1,3-dione, 1,3-Bis(4-chlorophenyl)propane-1,3-dione, and 1,3-Bis(4-bromo- phenyl)propane-1,3-dione, alongside different alkenyl bromides such as allyl bromide, (E)-1-Bromo-3,4-dimethylpent-2-ene, 1-Bromo-3-methylbut-2-ene, 3-Bromocyclohex-1-ene, and (E)-1-Bromohex-2-ene. These variations demonstrated the method’s versatility and the significant impact of substituents on reactivity and reaction yield. These findings highlight the importance of optimizing reaction conditions to maximize efficiency and provide insights into improving catalytic processes for enhanced product yields.

Substrate and Product Selective Supramolecular Catalysis by Pillar[5]arene in the Alkylation of Primary Linear Amines with Allyl Bromide

Substrate and Product Selective Supramolecular Catalysis by Pillar[5]arene in the Alkylation of Primary Linear Amines with Allyl Bromide

Stereoselective Approach to the Core Structure of (+)-Phainanoid A via Strategically Engineered Cascade Polyene Cyclization.

Stereoselective synthesis of 3b and its cascade polyene cyclization to 18b have been described. Acyclic polyene 3b was prepared from allyl bromide 4 and 1,3-dithiane 5, and intermediates 4 and 5 were synthesized from the commercially available geraniol (6) and cyclopenten-2-one (8), respectively, using enantioselective reduction of ketone, Johnson-Claisen rearrangement, and the Suzuki reaction as key steps. Au(I)-mediated diastereoselective polyene cyclization of 3b efficiently afforded tetracyclic compound 18b.

Amphiphilic diblock copolymers of polyisobutylene-b-poly(2-ethyl-2-oxazoline) via cationic polymerization

A series of amphiphilic polyisobutylene-b-poly (2-ethyl-2-oxazoline) (PIB-b-PEOX) diblock copolymer/Ag nanoparticle composites were successfully in-situ synthesized via cationic ring-opening polymerization of 2-ethyl-2-oxazoline (EOX) with high initiation efficiency by using allyl bromide end functionalized polyisobutylene (PIB-allylBr) as a macroinitiator and AgClO4 as a coinitiator. The microphase separation formed in the resulting PIB-b-PEOX diblock copolymers due to the thermodynamic imcompability of hydrophilic PEOX segments and hydrophobic PIB segments. The micromorphology of phase separation is dependent on the copolymer composition, in which sea-island micromorphology formed for PIB118-b-PEOX80 and bicontinuous phase micromorphology formed for PIB118-b-PEOX97. The micelles with nano-scale size in the range of 15–80 nm and having high drug loading rate of ca. 48.9 % can be formed by self-assembly of the amphiphilic diblock copolymers in n-hexane. The drug cumulative release rate can be increased with an increase in the proportion of PEOX segments, due to the strong interaction between ibuprofen and the PEOX segments. The hydrophilicity of the PIB-b-PEOX diblock copolymer surfaces can be improved after ethanol vapor induction. The PIB-b-PEOX diblock copolymers behave biocompatibility and good anti-protein adsorption property. The amphiphilic PIB-b-PEOX diblock copolymer/Ag nanoparticle composites exhibit high antibacterial efficiency for Gram-negative bacterium (E. coli) and Gram-positive bacterium (S. aureus). To the best of our knowledge, this is the first example of PIB-b-PEOX diblock copolymer/Ag nanoparticle (6.4 ± 2.6 nm) composites synthesized in-situ with good biocompatibility, anti-protein adsorption, and antibacterial properties, which would have potential applications for drug delivery and anti-protein coating in biomedical areas.

A Novel Family of Selenazolo[3,2-a]pyridinium Derivatives Based on Annulation Reactions and Comparative Analysis of Antimicrobial Activity of the Selenium and Sulfur Analogs of Chalcogenazolo[3,2-a]pyridiniums

The synthesis of a novel family selenazolo[3,2-a]pyridin-4-ium derivatives in high yields was developed based on the annulation reactions of 2-pyridineselenenyl chloride with unsaturated heteroatom and heterocyclic compounds. The analogous new thiazolo[3,2-a]pyridin-4-ium derivatives were obtained by the annulation reactions of 2-pyridinesulfenyl chloride. The reactions with vinylic ethers and N-vinylimidazole gave 3- substituted selenazolo[3,2-a]- and -[1,3]thiazolopyridin-4-ium derivatives, whereas reactions with allyl alcohol, allyl chloride, allyl bromide, 3-butenoic, 4-pentenoic and 5-hexenoic acids occurred with the opposite regiochemistry, affording 2-substituted [1,3]chalcogenazolo[3,2-a]pyridiniums. The antibacterial activity of the obtained products against gram-positive and gram-negative bacteria was evaluated, and compounds with high activity were discovered. A comparison of the antibacterial properties of [1,3]selenazolo[3,2-a]pyridin-4-ium derivatives with their sulfur analogs shows a higher activity of the selenium compounds.

Some Terminally Alkenyl-substituted Porphyrins: Synthesis and Attempts of Heck Reaction Leading to Porphyrin–Azulene Dyads

: The synthesis of meso-tetraphenylporphyrin derivatives, double functionalized in one of the phenyl rings (with a nitro group and carbon substituents), is described. 5-(4- Nitroaryl)-10,15,20-triarylporphyrinates react, in the presence of a base (t-BuOK), with carbanions containing a leaving group at the carbanionic center to give products of substitution of hydrogen at ortho-position to the nitro group via vicarious nucleophilic substitution scheme. Their alkylation with allyl bromide or 4-bromobut-1-en (t-BuOK/DMF, at 0-5°C) leads to porphyrins bearing side alkyl chain with a terminal double bond in yields of up to 82%. The above-mentioned double-substituted intermediates are very convenient substrates for Heck cross-coupling reaction. In this study, the synthesis of porphyrin–azulene dyads is reported. In some cases, the formation of highly conjugated systems is observed, with moderate yield. Their structures are interesting from both the porphyrin and azulene point of view.

Synthesis of cyclic sulfamides via one pot alkylation/aza-Michael cascade reaction

A straightforward and transition metal-free method for the synthesis of cyclic sulfamides via base-promoted bis-alkylation of tert-butyl (N-alkylsulfamoyl)carbamates with electron-deficient allyl bromides is described. All obtained cyclic sulfamides underwent successful removal of tert-butoxycarbonyl protecting group.

Electroreductive Cross‐Electrophile Coupling of Aromatic Carbonyl Compounds and Alkyl Bromides

AbstractClassical methods for the synthesis of tertiary alcohols mainly rely on the nucleophilic addition of organometallic reagents to carbonyl compounds. Here, we disclose a strategy for synthesizing tertiary alcohols via electroreductive cross‐electrophile coupling of aromatic carbonyl compounds and alkyl bromides (allyl, propargyl, benzyl and cyclohexyl bromides). This procedure features good substrate tolerance and friendly conditions (undivided cell, cheap and reusable carbon electrodes, reaction in open air, room temperature, without any external transition metal/activating reagent). Using this method, 32 desired products can be obtained with moderate to good yields, and gram‐scale synthesis is feasible, demonstrating the practicality of this approach.

Self-Assembly of a Hierarchical Metal-Organic Framework at the Liquid/Liquid Interface via π-π Stacking Manipulations in Organoplatinum(IV) Complexes for Methanol Fuel Cells.

This study focuses on the facile synthesis of the hierarchical architecture of zeolitic imidazolate framework-8 (ZIF-8) films containing an ultrasmall amount of Pt(0) by investigating the synthesis of different organoplatinum complexes and manipulating the π-π stacking effect in these complexes at the liquid/liquid interface. The organometallic Pt(IV) precursors were complexes with a formula of [PtXMe2(R)(bpy)] (bpy = 2,2'-bipyridine; for complex 2, R = CH2CH═CHC6H5 and X = Br; for complex 3, R = CH2CH═CH2 and X = Br; for complex 4, R = Me and X = I) prepared by oxidative addition of cinnamyl bromide, allyl bromide, or methyl iodide to [PtMe2(bpy)] (complex 1). Different thin films were synthesized starting from three organometallic Pt(IV) precursors (i) by reduction of the Pt complexes at the toluene/water interface (TF2-TF4), (ii) by encapsulation of the Pt precursors in a ZIF-8 (TF5-TF7), and (iii) by reduction of the Pt precursors onto a ZIF-8 (TF8-TF10). The self-assembly of ZIF-8 and different organoplatinum precursors at the interface of two immiscible liquids leads to the preparation of films with well-engineered structures such as rhombic dodecahedra, nanorods, hierarchical architectures, and nanowires, which are very difficult and complicated to synthesize under normal conditions. The ultralow loading of platinum complexes with different degrees of π-π stacking of dangling moieties has a great impact on the structure and morphology (directing agent), which in turn drastically changes the catalytic properties. The obtained films were applied as electrocatalysts for methanol oxidation in fuel cells. The electrocatalytic performance of organoplatinum containing a cinnamyl group in hierarchical architecture TF8 was found to be superior to those of nonhierarchical structures.

Metal-Free Decarboxylative Allylation of Oxime Esters under Light Irradiation.

Allylation reactions, often used as a key step for constructing complex molecules and drug candidates, typically rely on transition-metal (TM) catalysts. Even though TM-free radical allylations have been developed using allyl-stannanes, -sulfides, -silanes or -sulfones, much less procedures have been reported using simple and commercially available allyl halides, that are used for the preparation of the before-mentioned allyl derivatives. Here, we present a straightforward photocatalytic protocol for the decarboxylative allylation of oxime esters using allyl bromide derivatives under metal-free and mild conditions. This methodology yields a diverse variety of functionalized molecules including several pharmaceutically relevant molecules.

Regio- and Stereoselective α-Allylation with Enolates Prepared from N-C Axially Chiral Thiolactam and Lactam.

The reaction of allyl bromide derivatives with the enolate prepared from enantioenriched N-C axially chiral N-(2,5-di-tert-butylphenyl)-3,4-dihydroquinolin-2-one (lactam) and -thione (thiolactam) proceeded in a completely regio- and stereoselective manner to afford SN2 and SN2'-like products, respectively. Furthermore, through the conversion of thiolactam to lactam, the regiodivergent and stereoselective synthesis of N-C axially chiral lactams bearing a chiral tertiary α-carbon was achieved.

Visible-Light Induced Radical Addition-Elimination Reaction for Constructing Allylic Sulfones from Sulfonyl Chlorides and Allyl Bromides.

Allyl sulfones are commonly present in bioactive compounds and organic building blocks. This work introduces a photocatalytic radical addition-elimination reaction involving readily accessible sulfonyl chlorides and allyl bromides. It delivers structurally diverse allylic sulfones in moderate to excellent yields, showcasing a high tolerance to functional groups. Notably, this method operates under mild reaction conditions without the need for oxidants, stoichiometric reducing metals, or additives.

Stereocontrolled Synthesis of Phosphoproline Analogues Containing a trans-Fused Octahydroindole Bicyclic System.

Herein we report for the first time the diastereoselective synthesis of (2R,3aR,7aS)- and (2S,3aS,7aR)-octahydroindole-2-phosphonic acid (OicP trans-fused stereoisomers) from diethyl (R)- and (S)-phosphopyroglutamate derivative. The key steps of this procedure are the ruthenium tetroxide oxidation of enantiomerically pure diethyl (R)- and (S)-phosphoprolinate obtained through Katritzky's benzotriazole-oxazolidine methodology, a highly diastereoselective successive double 4,5-diallylation of diethyl (R)- and (S)-phosphopyroglutamate with allyl bromide and allyltrimethylsilane with a trans-addition mode, and a ring-closing metathesis with Grubbs' first-generation ruthenium catalyst.

Kaliendina S., Brynzei M., Kut M., Sukharev S.M., Ostapchuk Е., Onysko M. REGIOSELECTIVITY OF ALKYLATION OF 2-(THIOPHENE-2-IL)THIENO[2,3 d]PYRIMIDINE-4(3H)-ONE

Thieno[2,3-d]pyrimidines are an important class of heterocyclic compounds with a wide range of biological activities. The thieno[2,3-d]pyrimidin-4-one system is of the greatest interest to scientists, as it is one of a large number of possible thienopyrimidine derivatives. The presence of an amide fragment in these molecules allows for the introduction of various substituents via alkylation reactions. On the other hand, the presence of N- and O-nucleophilic centres makes it possible to form different types of alkylation products.
 In the present work, the alkylation reaction of 5,6-dimethyl-2-(thiophen-2-yl)thieno[2,3-d]pyrimidin-4(3H)-one, which contains N(3)- and O-nucleophilic centres for attacking alkylating reagents, was investigated. Allyl bromide was used as an alkylating reagent. It was found that the alkylation of 5,6-dimethyl-2-(thiophen-2-yl)thieno[2,3-d]pyrimidin-4(3H)-one with allyl bromide in DMF resulted in the regioselective preparation of 4-(allyloxy)-5,6-dimethyl-2-(thiophen-2-yl)thieno[2,3-d]pyrimidine, which can be used in the future to study the process of electrophilic intramolecular cyclisation. An increase in the reaction time of the starting reagents leads to an increase in the yield of the target ester.
 Keywords: 5,6-dimethyl-2-(thiophen-2-yl)thieno[2,3-d]pyrimidin-4(3H)-one; alkylation; regioselectivity; ether; 4-allyloxypyrimidine.

Синтез новых S-производных 4-амино-1,3,5-триазин-2-тиона и их исследование методами ЯМР 1Н, 13С и хромато-масс-спектрометрии

4-Amino-1,3,5-triazine-2-thione 1 interacts with allyl bromide, 2-methyl-3-chloro-1-propene, 2,3-dibromopropene-1, prenyl bromide in DMFA/K2CO3 and with cinnamyl chloride, butenyl bromide in DMFA/NaOH to form 4-allylsulfanyl- 2, 4-(2-methylpropene-2-yl)sulfanyl- 3, 4-(2-bromopropene-2-yl)sulfanyl- 4, 4-(2-methylbutene-2-yl)sulfanyl- 5, 4-cinnamylsulfanyl- 6 and 4-(butene-1-yl)sulfanyl-1,3,5-triazine-2-amines 7, respectively. The structure of compounds 2–7 was studied by 1H NMR, as well as of compounds 5 and 7, in their case including 13C NMR; allyl sulfide 2, prenyl sulfide 5 and butenyl sulfide 7 were also studied using chromatography mass spectrometry. In the 1H NMR spectra of compounds 2–7, the weakest field signal in the range of 8.22–8.30 p.p.m. is the signal of the aromatic proton of the triazine cycle, manifested as a singlet. The signals of protons of the S-CH2 group are observed in a strong field – at 3.10–4.19 p.p.m. – depending on the presence of electron donor or electron acceptor groups in the alkenyl fragment. The protons of the =CH2 group are present only in the structure of sulfides 2–4 and 7; they form two signals in the 1H NMR spectra: one signal at 4.85–5.58 p.p.m., the second at 5.03–6.10 p.p.m. In the 13C NMR spectra of prenyl sulfide 5 and butenyl sulfide 7, the carbon atoms of the S-alkenyl groups resonate in the region of strong fields. In the region of weak fields, the signals of aromatic carbon atoms of the 1,3,5-triazine cycle are observed: 182.32–157.95 p.p.m. In the mass spectra of compounds 2, 5 and 7, the characteristic peaks are [M 15]+ and [M-33]+ peaks, the formation of which is associated with the fragmentation of molecular ions undergoing cleavage of the methyl radical and the •SH radical, respectively. The haloalkyl derivative of the heterocyclic series – 2-chloro-1-(2,2,4-trimethyl-4-phenyl-3,4-dihydroquinoline-1(2H)-yl) ethanoate – in reaction with compound 1 has led to the introduction of a new pharmacophore fragment into the simm-triazine molecule, which contributes to the expansion of the spectrum of potential biological activity of its derivatives.

Reactivity Study of 4-Hydroxythiocoumarin: A Novel Synthetic Route to Fused Chromono-thiophene and -thiopyran Derivatives through Solvent-dependent Thio-Claisen Rearrangement

The alkylation of 4-hydroxythiocoumarins (1a-f) was carried out with various allyl bromides as well as propargyl bromides using K2CO3 (2 equiv.) in anhydrous acetone at room temperature, and the corresponding...

Synthesis and reactions of allylic azides of the adamantane series

A mixture of nucleophilic substitution product and isomeric azide resulting from [3,3]-sigmatropic rearrangement was obtained by interaction of allyl bromides of adamantane series with sodium azide. Epoxidation reactions of allylic azides of the adamantane series were investigated. The reduction of the obtained trans -2-(adamantan-1-yl)-3-(azidomethyl)oxirane with lithium alumohydride synthesized ( S *)-(adamantan-1-yl)[( S *)-aziridin-2-yl]methanol which, when heated with hydrochloric acid, gives the product of the aziridine ring opening is (1 S *,2 R *)-1-(adamantan-1-yl)-3-chloro-1-hydroxypropan-2-amino chloride.

Alkenylcopper Reagents Prepared from Stereodefined Alkenylboronate Esters. Reaction with Allylic Halides as a Convenient Route to Stereodefined 1,4-Dienes

The stereo-defined synthesis of 1,4-dienes based on in situ generated stereo-defined alkenylcopper reagents is presented. The hydroboration of alkynes with dibromoborane-methyl sulfide complex followed by treatment with trimethylene glycol provides stable (E)-1-alkenylboronate esters. These boronate esters readily undergo “ate” complexes with a hindered base such as potassium-tert.-butoxide. The transmetalation of the alkenyl group from boron to copper via the “ate” complexes retains the original stereochemistry defined from the starting alkenylboronate esters. The effect of representative bases on stereodefined alkenylboronate esters and subsequent reaction of these boronate esters in the transmetalation reaction with copper(I) bromidemethyl sulfide is investigated. The resulting stereo-defined alkenyl copper species generated in situ readily couple with allylic bromide to give the corresponding 1,4-dienes with retention of stereochemistry. Since (Z)-1-alkenylboronate esters are easily accessible, both cisand trans-isomeric 1,4-dienes are synthesized.