Allyl Isocyanate Research Articles

Regioselective tungsten-catalyzed decarboxylative amination of allylic alcohols with isocyanates.

Highly regioselective tungsten (W)-catalyzed decarboxylative allylic amination of allylic carbamates has been developed. Allylic carbamates can be generated in situ from readily available allylic alcohols and commercially available isocyanates. In the presence of a tungsten catalyst, branched allylic amines could be obtained in moderate to good yields with excellent regioselectivities (b/l > 20 : 1), and CO2 is the only byproduct. This reaction features mild conditions and a broad substrate scope, and aryl- and aliphatic-substituted allylic alcohols and isocyanates are suitable substrates.

Effects of Transmitted Light on Growth and Allyl isocyanate Content of Wasabi Rhizome Grown under Shading Nets Capable of Cutting Near-infrared Rays

Effects of Transmitted Light on Growth and Allyl isocyanate Content of Wasabi Rhizome Grown under Shading Nets Capable of Cutting Near-infrared Rays

Antiviral activity of amides and carboxamides of quinolizidine alkaloid (−)-cytisine against human influenza virus A (H1N1) and parainfluenza virus type 3

Novel derivatives of quinolizidine alkaloid (−)-cytisine were synthesised. ADME properties, cytotoxicity against HEK293 cells and activity against viruses of influenza A/California/07/09(H1N1)pdm09 virus (IAV) and human parainfluenza virus type 3 (HPIV3) were evaluated. It was shown, that 9-carboxamides of methylcytisine (with phenyl and allyl urea’s fragments) are most active compounds against IAV probably due to predicted in silico peculiarity of their interactions with the 4R7B active site of IAV neuraminidase. Indexes of selectivity (SI) calculated as ratio of CC50/IC50 of these ureas are 47 and 59 correspondingly. It was also found, that derivatives obtained from allyl isocyanate and (−)-cytisine or 9,11-dibromocytisine are able to inhibit a reproduction of HPIV3 with SI = 58 and 95. Moreover, last compound - (1 R,5R)-N-allyl-9,11-dibromo-8-oxo-1,5,6,8-tetrahydro-2H-1,5-methanopyrido[1,2-a][1,5]diazocine-3(4H)-carboxamide with two bromine atom in 2-pyridone core of starting (−)-cytisine molecule, demonstrated high activity against HPIV3 (SI = 95) and moderate activity against IAV (SI = 16).

Dispersion-driven conformational preference in the gas phase: Microwave spectroscopic and theoretical study of allyl isocyanate.

The conformations of allyl isocyanate (CH2=CHCH2N=C=O) were explored in the gas phase by combining theoretical calculations and Fourier transform microwave spectroscopy, including the chirped pulse and Balle-Flygare types. Three conformers (I, II, and III) were predicted using D3(BJ) dispersion-corrected B3LYP and MP2 methods; however, the lowest energy conformer (conf. I) was absent at the standard B3LYP level. The observed microwave spectra are consistent with the presence of both conf. I and III in the supersonic jet, and surprisingly, this is the first report of the global minimum conf. I both experimentally and theoretically. Rotational transitions from the parent species of both conformers as well as their minor isotopologues (13C, 15N, and 18O) in natural abundance were assigned allowing experimental geometries to be derived. For conf. I, in addition to the typical splitting pattern due to the 14N quadrupole nucleus, the transitions show a tunneling splitting which arises from the interconversion motion between its two mirror images. The experimental observation of conf. I and the absence of conf. II in the jet are rationalized using quantum-chemical calculations to explore the importance of electron correlation and in particular, demonstrate the necessity of including dispersion effects in density functional theory calculations even for seemingly small molecules.

Incorporating statistical strategy into image analysis to estimate effects of steam and allyl isocyanate on weed control.

Weeds are the major limitation to efficient crop production, and effective weed management is necessary to prevent yield losses due to crop-weed competition. Assessments of the relative efficacy of weed control treatments by traditional counting methods is labor intensive and expensive. More efficient methods are needed for weed control assessments. There is extensive literature on advanced techniques of image analysis for weed recognition, identification, classification, and leaf area, but there is limited information on statistical methods for hypothesis testing when data are obtained by image analysis (RGB decimal code). A traditional multiple comparison test, such as the Dunnett-Tukey-Kramer (DTK) test, is not an optimal statistical strategy for the image analysis because it does not fully utilize information contained in RGB decimal code. In this article, a bootstrap method and a Poisson model are considered to incorporate RGB decimal codes and pixels for comparing multiple treatments on weed control. These statistical methods can also estimate interpretable parameters such as the relative proportion of weed coverage and weed densities. The simulation studies showed that the bootstrap method and the Poisson model are more powerful than the DTK test for a fixed significance level. Using these statistical methods, three soil disinfestation treatments, steam, allyl-isothiocyanate (AITC), and control, were compared. Steam was found to be significantly more effective than AITC, a difference which could not be detected by the DTK test. Our study demonstrates that an appropriate statistical method can leverage statistical power even with a simple RGB index.

Gallium "Shears" for C=N and C=O Bonds of Isocyanates.

Digallane [L1 Ga-GaL1 ] (1, L1 =dpp-bian=1,2-[(2,6-iPr2 C6 H3 )NC]2 C12 H6 ) reacts with RN=C=O (R=Ph or Tos) by [2+4] cycloaddition of the isocyanate C=N bonds across both of its C=C-N-Ga fragments to afford [L1 (O=C-NR)Ga-Ga(RN-C=O)L1 ] (R=Ph, 3; R=Tos, 4). The reactions with both isocyanates result in new C-C and N-Ga single bonds. In the case of allyl isocyanate, the [2+4] cycloaddition across one C=C-N-Ga fragment of 1 is accompanied by insertion of a second allyl isocyanate molecule into the Ga-N bond of the same fragment to afford compound [L1 Ga-Ga(AllN- C=O)2 L1 ] (5) (All=allyl). In the presence of Na metal, the related digallane [L2 Ga-GaL2 ] (2; L2 =dpp-dad=[(2,6-iPr2 C6 H3 )NC(CH3 )]2 ) is converted into the gallium(I) carbene analogue [L2 Ga:]- (2 A), which undergoes a variety of reactions with isocyanate substrates. These include the cycloaddition of ethyl isocyanate to 2 A affording [Na2 (THF)5 ]{L2 Ga[EtN-C(O)]2 GaL2 } (6), cleavage of the N=C bond with release of 1 equiv. of CO to give [Na(THF)2 ]2 [L2 Ga(p-MeC6 H4 )(N-C(O))2 -N(p-MeC6 H4 )]2 (7), cleavage of the C=O bond to yield the di-O-bridged digallium compound [Na(THF)3 ]2 [L2 Ga-(μ-O)2 -GaL2 ] (8), and generation of the further addition product [Na2 (THF)5 ][L2 Ga(CyNCO2 )]2 (9). Complexes 3-9 have been characterized by NMR (1 H, 13 C), IR spectroscopy, elemental analysis, and X-ray diffraction analysis. Their electronic structures have been examined by DFT calculations.

Utilization of a Kinetic Principle of the Sequence-Controlled Anionic Copolymerization of Isocyanates toward Polyisocyanate Copolymers Encoded with Multiple Monomer Sequences

Furfuryl isocyanate (FIC), allyl isocyanate (AIC), and n-hexyl isocyanate (HIC) that have different β-carbon substituents were employed as monomers in living anionic homo- and copolymerization. The rate constants of the self- and cross-propagation reactions were determined, and their comparison showed the electrophilicity order of isocyanate as FIC > AIC > HIC. The kinetic analysis revealed that the anionic copolymerization of FIC:HIC, AIC:HIC, and FIC:AIC generated three different sequence-controlled polyisocyanate copolymers, poly(furfuryl isocyanate-block-n-hexyl isocyanate) (P(FIC-b-HIC)), poly(allyl isocyanate-tapered block-n-hexyl isocyanate) (P(AIC-tb-HIC)), and poly(furfuryl isocyanate-gradient-allyl isocyanate) (P(FIC-grad-HIC)), respectively. The homogeneous sequential anionic copolymerization of the binary isocyanate mixtures generated the polyisocyanate copolymers having repeated monomer sequences. A series connection of P(FIC-b-HIC), P(AIC-tb-HIC), and P(FIC-grad-HIC) segments in the copolyme...

Fabrication of hydrophilic medical catheter with hydrogel grafting and the in vivo evaluation of its histo-compatibility

The biocompatible hydrogel was fabricated under suitable conditions with natural dextran and polyethylene glycol (PEG) as the reaction materials. The oligomer (Dex-AI) was firstly synthesized with dextran and allylisocyanate (AI). This Dex-AI was then reacted with poly (ethyleneglycoldiacrylate) (PEGDA) under the mass ratio of 4∶6 to get hydrogel (DP) with the maximum water absorption of 810%. This hydrogel was grafted onto the surface of medical catheter via diphenyl ketone treatment under ultraviolet (UV) initiator. The surface contact angle became lower from (97 ± 6.1)° to (25 ± 4.2)° after the catheter surface was grafted with hydrogel DP, which suggests that the catheter possesses super hydrophilicity with hydrogel grafting. The in vivo evaluation after they were implanted into ICR rats subcutaneously verified that this catheter had less serious inflammation and possessed better histocompatibility comparing with the untreated medical catheter. Therefore, it could be concluded that hydrogel grafting is a good technology for patients to reduce inflammation due to catheter implantation, esp. for the case of retention in body for a relative long time.

Aluminium-catalysed isocyanate trimerization, enhanced by exploiting a dynamic coordination sphere.

Main-group metals are inherently labile, hindering their use in catalysis. We exploit this lability in the synthesis of isocyanurates. For the first time we report a highly active catalyst that trimerizes alkyl, allyl and aryl isocyanates, and di-isocyanates, with low catalyst loadings under mild conditions, using a hemi-labile aluminium-pyridyl-bis(iminophenolate) complex.

Preparation of Rearranged Allylic Isocyanates from the Reaction of Allylic Alcohols with 1-Cyano-4-dimethylaminopyridinium Bromide

A shorter and less costly alternative to Ichikawa’s [1,3]-transposition protocol for cyanates to isocyanates is described.

Fundamental Kinetics of Living Anionic Polymerization of Isocyanates Emerging by the Sodium Diphenylmethane-Mediated Initiation

Anionic polymerization of n-hexyl isocyanate (HIC) in THF at −98 °C under 10–6 Torr for the kinetic study was performed by the initiation of sodium diphenylmethane (NaDPM) in either the absence or presence of sodium tetraphenylborate (NaBPh4; [NaBPh4]0/[NaDPM]0 = 0 or 5). The common-ion effect of NaBPh4 to suppress the formation of unstable free amidate anions led to termination-free propagation by amidate ion pairs. In [HIC]0/[NaDPM]0 = 50.8/101/201, the initiation of NaDPM early reached ∼100% efficiencies during propagation, which led to the yield of poly(n-hexyl isocyanate)s (PHICs) with predictable molecular weights (Mn,theo = 6.50/12.7/24.7 kDa; Mn = 6.50/12.7/26.1 kDa) and low dispersities (Đ = 1.06/1.07/1.15). Within the conditions, the rate of propagation accorded with a first-order dependence on [NaDPM]0, indicating that the propagating amidate ion pairs are intrinsically unimeric (nonassociated). Kinetics of anionic copolymerization of HIC and allyl isocyanate (AIC) exhibited a monomer distribut...

Zwitterionic codeine-derived methacrylate monoliths for enantioselective capillary electrochromatography of chiral acids and chiral bases.

Thiol-ene click reaction of N-acetyl-L-cysteine methyl ester to codeine, followed by reaction with allyl isocyanate and hydrolysis to the corresponding zwitterionic chiral selector and its subsequent bonding to the surface of a methacrylate monolith provided a new chiral capillary column for enantiomer separation of chiral acids and chiral bases. First, the epoxy groups of a poly(glycidyl methacrylate-co-ethylene dimethacrylate) monolith were converted into amine residues, followed by reaction with allylglycidyl ether. In this way, a spacer arm was bonded to the surface before coating and cross-linking poly(3-mercaptopropyl methylsiloxane) (PMPMS) via radical addition (thiol-ene click reaction) to the surface. In order to improve the performance of the monolithic chiral stationary phase, thio ether and residual thiol groups were oxidized to sulfonyl and sulphonate groups, respectively. This novel chiral stationary phase (CSP) was evaluated by capillary electrochromatography (CEC) using two chiral model compounds, namely N-3,5-dinitrobenzoyl-R,S-leucine (retained by anion-exchange mechanism) and mefloquine (by cation-exchange process). The ion-exchange retention mechanism on the CSP was characterized for these two counterionic model solutes by varying the mobile phase composition, including the nature of solvents, the concentration of counter-ions and co-ions, and the acid-to-base ratio. A series of chiral β-blockers and amino acid derivatives was used to further check the performance of the modified monolith under the optimal conditions. Several enantiomers were baseline resolved with reasonable peak efficiencies (up to 60,000 theoretical plates per meter for the second eluted enantiomer).

Synthesis of Amphiphilic Helix–Coil–Helix Poly(3-(glycerylthio)propyl isocyanate)-block-polystyrene-block-poly(3-(glycerylthio)propyl isocyanate)

To achieve molecular packing of protic-functionalized helical polymers in aqueous solution, we synthesized an amphiphilic helix–coil–helix triblock copolymer (triBCP) composed of polystyrene and dihydroxyl-functionalized polyisocyanates. Poly(3-(glycerylthio)propyl isocyanate)-block-polystyrene-block-poly(3-(glycerylthio)propyl isocyanate), P3GPIC-b-PSt-b-P3GPIC, was synthesized by postpolymerization modification. The bidirectional anionic block copolymerization of styrene (St) and allyl isocyanate (AIC) yielded triBCPs, poly(allyl isocyanate)-block-polystyrene-block-poly(allyl isocyanate)s (PAIC-b-PSt-b-PAICs), with well-controlled molecular weights (Mn = 5.60–99.9 kDa) and narrow dispersities (Đ = 1.14–1.18). Of them, one with the lowest MW (Mn = 5.60 kDa, Đ = 1.14), which was highly organic-soluble, was utilized in the thiol–ene click reaction between allyl group and 1-thioglycerol, producing P3GPIC-b-PSt-b-P3GPIC. The amphiphilic P3GPIC-b-PSt-b-P3GPIC self-aggregated to form spherical vesicles with an...

Regioselectivity of aryl radical attack onto isocyanates and isothiocyanates.

The combination of multistage mass spectrometry experiments employing the distonic radical approach together with DFT calculations are used to examine addition of the N-methyl-pyridinium-4-yl radical cation (γ-NMP) to iso(thio)cyanates in the gas-phase. The type of products formed depend on the nature of the iso(thio)cyanate: (1) hydrogen atom abstraction occurs for alkyl isocyanates; (2) aryl isocyanates undergo radical-ipso substitution; (3) radical attack occurs at the C[double bond, length as m-dash]C bond of allyl isocyanate; (4) radical attack occurs at the C[double bond, length as m-dash]S bond of isothiocyanates to generate S adducts of γ-NMP and isonitriles. DFT calculations provide insight into the reactivity differences of these heterocumulenes towards the electrophilic C-centered γ-distonic radical cations. Translation of these gas phase results to the solution phase were hampered by dominating radical recombination reactions which appear to be favoured over the radical-iso(thio)cyanate reactions.

Palladium‐Catalyzed Synthesis of Allylic Ureas via an Isocyanate Intermediate

AbstractA palladium‐catalyzed coupling of allylic carbonates with trimethylsilylisocyanate to provide allylic isocyanates is reported. Amines are added in a second step to yield allylic ureas in this one‐pot procedure. Use of a bidentate phosphine ligand with a large bite angle was found to be important in this transformation. The scope of allylic carbonates has been examined, as well as amines compatible with these reaction conditions.

The Synthesis of α,α-Disubstituted α-Amino Acids via Ichikawa Rearrangement.

An approach to α,α-disubstituted α-amino acids is reported. The key step is allyl cyanate-to-isocyanate rearrangement. As demonstrated, the resultant allyl isocyanates can be directly trapped with various nucleophiles, for instance, alcohols, amines, and organometallic reagents, to provide a broad range of N-functionalized allylamines. The developed method has been successfully applied in the synthesis of two bioactive peptides: 2-aminoadamantane-2-carboxylic acid derived P2X7-evoked glutamate release inhibitor and 4-amino-tetrahydropyranyl-4-carboxylic acid derived dipeptide GSK-2793660, which is currently in clinical trials as cathepsin C inhibitor for the treatment of cystic fibrosis, noncystic fibrosis bronchiectasis, ANCA-associated vasculitis and bronchiectasis.

Renewable epoxy networks by photoinitiated copolymerization of poly(3-hydroxyalkanoate)s and isosorbide derivatives

New biodegradable epoxy networks derived from poly(3-hydroxyalkanoate)s and isosorbide were synthesized by photoinitiated cationic ring opening polymerization in the presence of diaryl iodonium salt (I 250). Bis-epoxidized terminated PHA oligomers, PHA-diepoxy, were first prepared in three steps, microwave assisted alcoholysis in the presence of ethylene glycol, condensation with allyl isocyanate and epoxidation of alkene terminal groups. Moreover, isosorbide diglycidyl ether (DGEDAS) was prepared by epoxidation of allylic derivative. The photoinitiated polymerization is a straightforward way applied at room temperature in a very short reaction time (i.e. 300s) to obtain renewable crosslinked networks that remain partially biodegradable by lipase. Higher degradability was observed by increasing the content of PHA.

Multifunctional Poly[N-(2-hydroxypropyl)methacrylamide] Copolymers via Postpolymerization Modification and Sequential Thiol–Ene Chemistry

Poly[N-(2-hydroxypropyl)methacrylamide] is a promising candidate material for biomedical applications. However, synthesis of functional pHPMA via compolymerization results can lead to variations in monomer composition, molar mass, and dispersity making comparison difficult. Postpolymerization modification routes, most commonly aminolysis of poly[active ester methacrylates], have alleviated some of these problems, but ester hydrolysis can lead to other problems. Here we report the synthesis of multifunctional pHPMA via a simple two-step derivatization of pHPMA homopolymer using readily available standard reagents and atom-efficient procedures. First, treatment with allyl isocyanate yields the corresponding carbamate with predictable incorporation of side-chain functionality. Allyl-pHPMA can then be derivatized further via radical thiol–ene reactions to generate pHPMA with multiple diverse functionalities but without adverse effects on the molecular weight and dispersity of the polymer. The applicability of...

ChemInform Abstract: Metal‐Free Metathesis Reaction of C‐Chiral Allylic Sulfilimines with Aryl Isocyanates: Construction of Chiral Nonracemic Allylic Isocyanates.

AbstractC‐chiral allylic sulfilimines primarily react with aryl isocyanates and the intermediary formed allylic isocyanates are trapped with nucleophiles giving unsymmetrical ureas, carbamates, thiocarbamates, and amides.

Electroactive shape memory performance of polyurethane/graphene nanocomposites

A series of electroactive shape memory polyurethane (SMPU) nanocomposites were synthesized from poly(tetramethylene ether) glycol (PTMG), 4,4-methylenebis(phenyl isocyanate) (MDI) and 1,3-butandiol (1,3-BD) with the addition of various amounts of thermally reduced graphenes (TRG) which were chemically modified with allyl isocyanate (iTRG). The effects of iTRG on electroactive shape recovery behaviors as well as the conventional direct heat actuated SMPU material have been studied in terms of morphological, thermal, mechanical, electrical properties and thermomechanical cyclic behavior. It was found that significant increases in electrical conductivity and temperature were obtained high iTRG contents (>2%) to electrically actuate the nanocomposite, along with large increases in glass transition temperature (Tg) and initial modulus with a dramatic drop in elongation at break.