A study of the cyclotrimerisation and polymerisation of aryl cyanates using 13C and 15N nuclear magnetic resonance spectroscopy,fourier transform infra-red spectroscopy and differential scanning calorimetry

Summary Three aryl cyanates, together with the products of the cyclotrimerisation of the cyanates to form aryloxy-s-triazines, have been characterised by ¹³C and ¹⁵N nmr spectroscopy. A quantitative nmr technique is proposed which allows the monitoring of the conversion of both monofunctional and difunctional cyanates to the corresponding triazines. The results compare favourably with those obtained using Fourier transform infra-red spectroscopy (FTIR) and differential scanning calorimetry (DSC) techniques.     

Struktur und Reaktivität heterosubstituierter Nitrile. XIX [1]. Kinetik und Mechanismus der Addition sekundärer aliphatischer Amine an Arylcyanate

Structure and Reactivity of Heterosubstituted Nitriles. XIX. Kinetics and Mechanism of the Addition of Secondary Aliphatic Amines to Aryl Cyanates The N,N-dialkyl-O-aryl isourea formation by the addition of secondary aliphatic amines to aryl cyanates was studied by kinetic methods in dioxane and dioxane water mixtures. Linear relationships between the rate constants and the water concentrations, the basicity of the amines and the electrophilicity of the aryl cyanates have been found. These data and the activation parameters support two concurrent reactions, a direct nucleophilic attack of the amine to aryl cyanate and one involving a six membered transition state between a molecule of cyanate, amine and water.     

Struktur und Reaktivität heterosubstituierter Nitrile. XVII [1]. Kinetik und Mechanismus der Phenol-Addition an Arylcyanate in Gegenwart tertiärer Amine

Structure and Reactivity of Heterosubstituted Nitriles. XVII. Kinetics and Mechanism of the Addition of Phenols to Aryl Cyanates in Presence of Tertiary Amines The rate of carbonic acid diaryl ester imides formation by the addition of phenols to aryl cyanates in the presence of tertiary amines was determined by IR-spektroscopy. The rate constants are first order in aryl cyanates and correlate linear with [ArOH] [ArO⁻ ∥ R₃NH⁺]. The third order rate constants depend linear on the (σ + σ⁻)-values of the phenol substituents, the σ⁰-values of the aryl cyanate substituents, and the pK_a of the tertiary ammonium salts. These results support a transition state formed by the nucleophilic attack of a phenoxide trialkyl ammonium ion pair to an aryl cyanate phenol associate.     

Acylierung von Heterocyclen mit Kohlensäurederivaten. I. Kinetik und Mechanismus der Reaktion von 2-Aminobenzimidazolen mit Arylcyanaten

Acylation of Heterocycles with Carbonic Acid Derivatives. I. Kinetics and Mechanism of the Reaction of 2-Aminobenzimidazoles with Aryl Cyanates The second order rate constants for the reaction of 2-amino-benzimidazoles (2-ABI) with aryl cyanates forming 2-amino-benzimidazole aryl ester imide 3 have been determined in dependence on substituent effects by u. v. measurements. The results are interpreted by a six-membered cyclic transition state in which the electrophilic attack of the cyanate on the endocyclic N atom is catalyzed by an H bridge interaction of the exocyclic amino group of 2-ABI with the OCN group.     

Cyansäureester. 29. Benzoxazolin-thion-N-imidsäureester und ihre Folgereaktionen

Cyanic Acid Esters. 29. Benzoxazoline-thione-N-imid Esters and Their Consecutive Reactions Oxazoline-thiones-(2) and aryl cyanates react to form the corresponding isoureas 4 . These compounds are remarkably stable against electrophilic reagents. The aminolysis of 4 proceeds two pathways: a transformation of the imid ester residue to the amin and a ring opening reaction by attack of the amin to the CS-bond. The hydrazinolysis causes a ring-transformation of the oxazoline- to the 1,3,4-triazole system.     

Struktur und Reaktivität heterosubstituierter Nitrile. XX [1]. Kinetik und Mechanismus der Addition primärer aliphatischer Amine an Arylcyanate

Structure and Reactivity of Heterosubstituted Nitriles. XX. Kinetics and Mechanism of the Addition of Primary Aliphatic Amines to Aryl Cyanates The addition rate of primary aliphatic amines to aryl cyanates in water/dioxane mixtures was measured by u.v.-spectroscopy. The second order rate constants give a linear correlation with the concentration of water. The rate of the addition is increased by growing electrophilicity of the aryl cyanates and decreased by steric hindrance of the amine substituents. The nucleophilicity of the amine has no influence on the reaction rate. The results are explained by a six-membered cyclic transition state, in which the nucleophilic attack and the proton transfer proceed with equal rate.     

Struktur und Reaktivität heterosubstituierter Nitrile. 24 Kinetik und Mechanismus der Reaktion von o-Phenylendiamin mit Arylcyanaten

Structure and Reactivity of Heterosubstituted Nitriles. 24. Kinetics and Mechanism of the Reaction of o-Phenylen diamine with Aryl Cyanates The second and third order rate constants for the reaction of o-phenylene diamine with aryl cyanates to 2-amino benzimidazole phenylester imide in water/dioxane have been determined by i.r. measurements. The reaction proceeds through a bimolecular and a trimolecular mechanism simultaneously. In the slow step of the bimolecular process an electrophilic attack of the aryl cyanate on o-phenylene diamine takes place in a seven membered cyclic transition state. The slow step of the trimolecular mechanism consists of a nucleophilic attack of the diamine on a phenole aryl cyanate associate by a six membered cyclic transition state. The final products of both reactions are formed by successive fast reactions.     

Struktur und Reaktivität heterosubstituierter Nitrile. XVIII [1]. Kinetik und Mechanismus der Alkohol-Addition an Arylcyanate in Gegenwart tertiärer Amine

Structure and Reactivity of Heterosubstituted Nitriles. XVIII. Kinetics and Mechanism of the Addition of Alcohols to Aryl Cyanates in Presence of Tertiary Amines The mechanism of the carbonic acid arylester imide or carbamic acid arylester formation by the addition of alcohols or water to aryl cyanates in the presence of tertiary amines has been studied. After a slow formation of an autocatalyst, an intermediate is formed in a fast equilibrium between this one and a molecule of aryl cyanate and tertiary amine. This intermediate is slowly alcoholyzed to carbonimidic acid diester which in part is fragmented by the base to phenole and alkyl cyanate. The alkyl cyanate undergoes further reaction with the alcohol and the amine to dialkyl ether and trialkyl ammonium cyanate in the reaction mixture.     

Über die Reaktionen von Benzimidazol-2-carbonsäurehydrazid mit Elektrophilen

About the Reactions of Benzimidazole-2-carbohydrazide with Electrophilic Compounds Benzimidazole-2-carbohydrazide ( 1 ) reacts with aldehydes and ketones to form N-alkylidene-benzimidazole-2-carbohydrazides( 2a–j ). With carbon disulfide, diphenyl carbonate and cyanates, ring closure takes place to afford 1,2,4-triazines and 1,3,4-oxadiazoles. Attempts to synthezise 2-isocyanato-benzimidazole failed. ¹H-n.m.r. and ¹³C-n.m.r. spectroscopic data of the compounds are given.     

异氰酸酯的合成与应用

介绍了烷基单异氰酸酯、（取代）苯基单异氰酸酯、α－取代苄基异氰酸酯、多异氰酸酯等几个重要的异氰酸酯化合物。评述了其在农药及医药合成、聚氨酯涂料和胶粘剂上的应用。建议结合下游产品重点开发正丁基异氰酸酯、苯基异氰酸酯、ｍ－（或ｐ－）ＴＭＸＤＩ、ｍ－ＴＭＩ、ＩＰＤＩ、ＨＤＩ等化合物。     

Acylwanderungen am 3(5)-Amino-pyrazol

Acyl Migrations on 3(5)-Amino-pyrazole 3(5)-Amino-pyrazole 1 form 3 isomeric monoacylation products, 4 diacylation products and 3 triacylation products by reaction with electrophiles like cyanates, isocyanates or carboxylic and chlorides, respectively. Acyl migrations are observed depending on the reaction temperature and the structure of the acyl residue. The structures of the acyl derivatives of 3(5)-amino-pyrazole were characterized by nmr-spectroscopy.     

Cyclisierungsreaktionen von 1-[2-Amino-1-cyan-2-thio-]ethylen-pyridiniumbetainen

Cyclization Reactions of 1-[2-amino-1-cyano-2-thio-]ethenepyridinium Ylides 1-[2-Amino-1-cyano-2-thio-]ethene-pyridinium ylides 1 can be alkylated with methyliodide or α-haloesters and α-haloketones, respectively, to form 1-[2-alkyl(aryl)amino-1-cyano-2-methylthio-ethene-1]pyridinium iodides 2a-–e or 1-[2-alkyl(aryl)-amino-1-cyano-2-alkoxy(aryl)-carbonylmethylthio-ethene-1] pyridinium salts 3a–f . With the exception of 3a–b the compounds 3 or 1 react with haloketones to yield 1-[4-amino-2-alkyl-(aryl)amino-5-benzoyl-thiene-3]pyridinium salts 4a–m or 3-alkyl-4-aryl-2-(1-cyano-1-pyridinium)methylene-Δ⁴-thiazoline salts 5a–f .     

Inter- und intramolekulare Acylwanderungen an 1(9)H-2,3-Dihydro-imidazo[1,2-a]benzimidazolen

Inter- and Intramolecular Acyl Transfer on 1(9)H-Imidazo[1,2-a]benzimidazoles The new imidazo[1,2-a]benzimidazoles ( 3 ) react with electrophiles like aroyl chlorides, isocyanates, cyanates, chloroformates and chlorothioformates to give the 9-acyl derivatives ( 4a – 1 ). At higher temperatures intermolecular acyl transfer takes place to give the l-acyl compounds ( 5a – m ). In the case of 1-carbamoyl imidazo[1,2-a]benzimidazoles ( 5 ) was observed intramolecular acyl transfer in the presence of strong bases and 1-benzimidazol-2-yl-hydantoins ( 6 ) were isolated. The structures of the prepared compounds could be inferred from their ¹H and ¹³C n.m.r., mass spectra and were corroborated by the comparison with the data of similar derivatives as well as by chemical means.     

Spaltung von 1,2,4-Thiadiazol-3-onen mit Triphenylphosphan: Triphenylphosphonio-thioimidazolate und ihre Folgereaktionen

Fission of 1,2,4-Thiadiazol-3-ones by Triphenylphosphane: gewidinet Triphenylphosphonio Thioimidazolates and Their Consecutive Reactions Treatment of benzimidazo[1,2-d][1,2,4]thiadiazol-3(2H)-ones ( 1 ) and imidazo[1,2-d]-[1,2,4]thiadiazol-3(2H)-ones ( 17 ) with triphenylphosphan leads to the liberation of isocyanate and the formation of triphenylphosphonio-thiobenzimidazolat ( 4 ) and triphenylphosphonio-thioimidazolat ( 18 ), respectively. 2,4-Diphenyl-5-phenylimino-1,2,4-thiadiazol-3-one ( 23 ) is desulfurized with Ph₃P and decomposed into phenyl isocyanate and diphenylcarbodiimide whereas the N-unsubstituted imino-thiadiazol-3-one ( 25 ) is attacked at the exocyclic imino group by Ph₃P to give the N-phosphoranylidene thiourea ( 26 ). The structure of 4 can be rationalized as a dynamic system between polar and apolar valence isomeres. Reactions of 1 and 17 with cyanates, isocyanates, carbon disulfide, acetic anhydride, amines, benzyl chloride, grignard compounds, and CH acidic compounds are described.     

Silicone as an organosilicon reagent for the palladium-catalyzed cross-coupling reaction

Silicone, poly(diorganosiloxane), serves as an organosilicon reagent for palladium-catalyzed cross-coupling reactions. Treatment of poly[(aryl)methylsiloxane], poly[(alkenyl)methylsiloxane], or cyclic oligosiloxanes with various aryl iodides in the presence of silver(I) oxide (Ag₂O) or tetrabutylammonium fluoride (TBAF) and a catalytic amount of palladium affords the corresponding cross-coupling product in a good to excellent yield. The reaction of silicone with aryl chlorides in the presence of K₂CO₃/H₂O as an activator proceeded to afford biaryl derivatives in moderate to excellent yields. A wide range of aryl chlorides bearing an electron-donating or electron-withdrawing substituent on the aromatic ring are tolerated.     

Hydrophosphorylation of vinyl sulfides with elemental phosphorus in the KOH/DMSO(H2O) system: synthesis of 2-alkyl(aryl)thioethylphosphinic acids

Elemental phosphorus (red or white) reacts with alkyl and aryl vinyl sulfides in the superbase system KOH/DMSO(H₂O) at 75–120°C for 2–3?h to afford 2-alkyl(aryl)thioethylphosphinic acids in a yield of up to 31%.     

叔丁醇钾促进的对甲苯磺酰基氮杂环丙烷与取代炔丙醇反应研究

以叔丁醇钾作为促进剂,采用正丁基、氢基、芳基取代的炔丙醇(2),与(S)-型或消旋对甲苯磺酰基氮杂环丙烷(1)分别发生开环、开环/异构化、开环/异构化/关环,从而得到不同的产物(2-炔-1-基氧代-2-基-4-甲基苯磺酰胺衍生物3、丙-1,2-二烯氧-2-基-4-甲基苯磺酰胺衍生物4或4-对甲苯磺酰基-1,4-噁嗪衍生...     

A Synergic Blend of Newly Isolated <Emphasis Type="Italic">Pseudomonas mandelii</Emphasis> KJLPB5 and [hmim]Br for Chemoselective 2° Aryl Alcohol Oxidation in H<Subscript>2</Subscript>O<Subscript>2</Subscript>: Synthesis of Aryl Ketone or Aldehydes via Sequential Dehydration-Oxidative C=C Cleavage

Abstract  

Pseudomonas mandelii KJLPB5 is reported for the oxidation of aryl alcohols in ionic liquid [hmim]Br (1-hexyl-3-methyl imidazolium bromide) with H₂O₂. With a slight alteration of reaction conditions, the developed protocol leads either to (i) chemoselective oxidation of 2° aryl alcohols over 1° and aliphatic counterparts or (ii) direct one pot-two step sequential conversion of 2° aryl alcohols into corresponding one or two carbons shorter aryl aldehydes through oxidative cleavage pathway, thus providing a new facet to metal-free oxidations. The key operational parameters such as substrate concentration, incubation temperature, incubation time, ionic liquid type and ionic liquid concentration are also optimized.     

Hybrid Organic‐Inorganic Materials from Di‐(2‐pyridyl)methylamine‐Palladium Dichloride Complex as Recoverable Catalysts for Suzuki,Heck and Sonogashira Reactions

Hybrid silica materials containing the di‐(2‐pyridyl)methylamine‐palladium dichloride complex, prepared by sol‐gel cogelification, are efficient recyclable catalysts for Suzuki (aryl bromides and chlorides), Heck (aryl bromides) and Sonogashira reactions (aryl iodides and bromides). Formation of palladium(0) nanoparticles is observed in the Suzuki and Heck reactions but not in the Sonogashira coupling.     

Palladium‐Catalyzed Efficient and One‐Pot Synthesis of Diarylacetylenes from the Reaction of Aryl Chlorides with 2‐Methyl‐3‐butyn‐2‐ol

An efficient and practical synthetic method has been developed for the preparation of symmetrical diarylacetylenes from the direct reaction of aryl chlorides with 2‐methyl‐3‐butyn‐2‐ol catalyzed by palladium(II) chloride‐bis(tricyclohexylphosphine) [PdCl₂(PCy₃)₂] under mild reaction conditions. Unsymmetrical diarylated acetylenes could be also obtained by using two different aryl chlorides simultaneously. The catalytic procedure includes a novel one‐pot palladium‐catalyzed, double Sonogashira coupling of inactivated aryl chlorides without use of copper(I) as co‐catalyst.