Organylthiochloroacetylenes: V. Dimerization of Alkylthiochloroacetylenes in the Presence of Sodium Sulfite

Alkylthiochloroacetylenes dimerize at room temperature in the system sodium sulfite-polar nonhydroxyl solvent (DMSO, DMF, HMPA) to form in 40-63% yields (Z)-1,4-bis(alkylthio)-1,2-dichloro-1- buten-3-ynes which are promising polyfunctional monomers and building blocks for fine organic synthesis. The structure of the resulting dimers was established by means of IR and ¹H and ¹³C NMR spectroscopy, X-ray fluorescent analysis, and dielcometry and confirmed by mass spectrometry and elemental analysis.     

Organylthiochloroacetylenes: IV. Reaction with Thiourea

Alkylthiochloroacetylenes react with thiourea in acetone to form S-(alkylthioethynyl)isothiuronium chlorides and N-[1-(alkylthio)ethylidene]thioureas; phenylthiochloroacetylene reacts with thiourea to give 4-(phenylthio)-2-imino-1,3(3H)-thiazole hydrochloride.     

Organylthiochloroacetylenes: III. Nucleophilic Addition of Di(2-phenylethyl)phosphine Oxide to Alkylthiochloroacetylenes: Configuration and Conformation of Adducts

Alkylthiochloroacetylenes regio- and stereospecifically react with di(2-phenylethyl)phosphine oxide in dioxane at 20-22°C in the presence of potassium hydroxide to form 1-chloro-2-(alkylthio)vinyl[di(2-phenylethyl)]phosphine oxides in a 78-85% yield. According to IR and ¹H and ^{3 1}P NMR data, dielectrometric measurements, and quantum-chemical calculations, the obtained adducts have the Z configuration and exist mainly in the sp,sp conformation.     

过渡金属催化有机腈和叠氮酸钠反应机理的研究

过渡金属催化有机腈和叠氮酸钠反应机理的研究一直是一个具有挑战性的课题.本工作组合理论和实验方法,对其反应机理作了深入的探讨.基于对两种类型中间体(H₂O)3M…N₃^–和(H₂O)₃M…NCCH₃稳定性的理论分析和中间体Cd₂(μ₃-N₃)(μ₃-OH)(μ₅-CHDA)(1)和Cd(μ₂-N₃)(μ₃-IBA)(2)(H₂CHDA为1,3-环己二酸, HIBA为4’-(咪唑-1-基)苯甲酸)的成功捕获,首次从实验和理论上揭示了过渡金属离子在反应中起活化叠氮酸根的作用.此外,基于中间体(H₂O)₃M…N₃^-和乙腈分子的静电势盆分析的结果,揭示了叠氮酸根未配位的端基N原子可以进攻...     

Organylthiochloroacetylenes: IX. Reactions with geminal and vicinal dithiols

Alkylthiochloroacetylenes react with geminal (in ether) and vicinal (in THF) dithiols to form, respectively, functional 1,3-dithiolenes (yield 43%) or 1,3-dithiolanes (yield 34%).     

Perfluoroaryl Azide Staudinger Reaction: A Fast and Bioorthogonal Reaction

We report a fast Staudinger reaction between perfluoroaryl azides (PFAAs) and aryl phosphines, which occurs readily under ambient conditions. A rate constant as high as 18 m ⁻¹ s⁻¹ was obtained between methyl 4‐azido‐2,3,5,6‐tetrafluorobenzoate and methyl 2‐(diphenylphosphanyl)benzoate in CD₃CN/D₂O. Furthermore, the iminophosphorane product was stable toward hydrolysis and aza‐phosphonium ylide reactions. This PFAA Staudinger reaction proved to be an excellent bioothorgonal reaction. PFAA‐derivatized mannosamine and galactosamine were successfully transformed into cell‐surface glycans and efficiently labeled with phosphine‐derivatized fluorophore‐conjugated bovine serum albumin.     

Spectrophotometric Determination of Azide Ion Through Carbon Disulphide - Azide Reaction

Abstract

The azide ion can be converted quantitatively into 1,2,3,4, - thiatriazol - 5 - thiolate ion by treatment with carbon disulphide in aqueous ethanolic medium. The CS₂N₃ ^? concentration is measured spectrophotometrically at 321nm, where ?= 7. 8 × 10³ l mol^?1 cm^?1. The conditions outlined below provide a rapid, simple and precise method to determine the azide ion at the 8 μg/ml level.The influence of several foreign ions on the proposed method is also studied.     

N-haloamidines. VI. Reaction of n-chloro-n'-benzenesulfonylbenzamidines with enamines

The reaction between N-chloro-N'-benzenesulfonylbenzamidines and ß,ß-disubstituted enamines affords N-(benzenesulfonyl)-N'- [(2-chloro-2-substituted-l-amino)-propyl]-benzamidines. When both ß-substi tuents are methyl groups the open chain adducts have been isolated and characterized; whereas, when one of the two substituents is a phenyl group, they have been characterized only by PMR because of the easy cyclization to 1-benzenesulfonyl-4, 5-dihydroimidazoles.     

叠氮二乙基铝合成及其相关反应的研究

在芳烃溶剂中用氯化二乙基铝和叠氮化钠反应合成了叠氮化二乙基铝(DEAA),其产率高达87%,比文献值高出17%。在正己烷中没有合成出DEAA,在含30%四氢呋喃(THF)的正己烷中合成出DEAA·THF配合物。在芳烃溶剂中,随着苯环上甲基数目的增加,DEAA的收率增加。测定了氯化二乙基铝、氯化二乙基铝的正己烷溶液、氯化二乙基铝的甲苯溶液的 ²⁷Al NMR谱。由 ²⁷Al NMR谱数 据确定了氯化二乙基铝在甲苯中解离平衡式,计算了氯化二乙基铝在甲苯中解离平衡的热力学数据。用DEAA与苯甲酸甲酯直接合成了苯甲酰叠氮,并表征了其结构。这是一个新反应,至今无文献报导。用实验证明了在正己烷溶液中,用氯化二乙基铝、叠氮化钠与苯甲酸甲酯合成苯甲酰叠氮,没有经过氯化二乙基铝和叠氮化钠反应生成中间体DEAA的这一步。依据实验事实建立了上述三种反应的反应机理。     

A DFT Study on the Reaction Mechanism Involved in the Synthesis of Sodium Azide via Hydrazine Hydrate Method

Sodium azide is a widely used inorganic compound. Besides the commonly used method of "Wislicenus process" which uses ammonia, nitrous and sodium as materials, the hydrazine hydrate route is also employed for the preparation of sodium azide particularly in laboratory. However, because many species are involved in the reaction system, the reaction details for the hydrazine hydrate route are still unclear. A comprehensive understanding of the reaction mechanism may provide meaningful help for optimizing the production process. In this work, the reaction mechanism for the synthesis of sodium azide by hydrazine hydrate route has been studied using density function theory(DFT) method. On the basis of our calculations, the reaction details, including the energetics of ten elementary steps, the structures of intermediates and transition states as well as the influence of inorganic acids and alcohols, were illuminated at the atomistic level. Both the two steps, the generation of key intermediate(NH_2-NH-NO) and the trans-cistransformation of NH_2-NH-NO, are suggested to be the possible rate-limiting step, corresponding to the energy barriers of 20.3 and 22.7 kcal/mol, respectively. In the early reaction steps to generate NH_2-NH-NO, the main role of sulphuric acid is to donate proton, which can be replaced by nitric acid or hydrochloric acid. From the energy point of view, isopropanol has similar reactivity as methanol and ethanol.     

Acetylenic ketones. Part VI. Reaction of aroylphenylacetylenes with hydrazine derivatives

The reaction of aroylphenylacetylenes (I) with acyl- or aroylhydrazines (II) gave ω-aroyl-acetophenone-N-acyl or N-aroylhydrazones (IV). The latter gave upon treatment with methanolic potassium hydroxide and with acetic anhydride in the presence of sodium acetate, the corresponding pyrazoles (V) and the N-acetylpyrazoles (VII and VIII), respectively. The acetylenic ketones ( 1 ) also reacted with methylhydrazine and 1,1-dimethylhydrazine to give 5-aryl-1-methyl-3-phenylpyrazoles (XII), and 1,1-dimethylhydrazine derivatives (XIII), respectively. When the latter compounds were heated with acetic anhydride, they gave the N-methylpyrazoles (XII).     

硝普钠与苯肼的反应

有氧存在下 ,硝普钠 (Na2 [Fe(CN) 5NO] )与苯肼类化合物在N ,N 二甲基甲酰胺中作用 ,发生脱肼反应 ,生成叠氮苯、苯衍生物、微量的苯胺及偶氮化合物 .对可能的反应机理进行了讨论     

Phase-Transfer Catalyzed Additions. VI. Reaction of N-Diphenylmethyleneaminoacetonitrile with Aromatic Aldehydes

The phase-transfer catalyzed reaction of N-diphenylmethyleneaminoacetonitrile with aromatic aldehydes affords 4-aryl-3-cyano-1,1-diphenyl-2-aza-1,3-butadienes (3) in good yields.     

Reaction of Hexachlorocyclotriphosphazene with Sodium p-Cresoxide

The reaction of hexachlorocyclotriphosphazene (N₃P₃Cl₆) with sodium p-cresoxide proceeds by a predominantly nongeminal pathway. The presence of geminal isomers at the bis- and tris-stages of substitution in tiny quantities (< 5%) has also been observed. All the chloro(p-cresoxy)cyclotriphosphazenes and their dimethylamino derivatives have been characterized by ¹H-, ¹³C{¹H}-, and ³¹P{¹H}-NMR spectroscopy. The reaction of N₃P₃Cl₆ with sodium phenoxide has been reinvestigated. The relative yields of the products at various stages of substitution and their isomeric compositions are almost the same for both phenoxy and p-cresoxy systems. Possible mechanisms to explain the observed isomeric compositions are discussed. A “through-space” interaction involving oxygen-2p and phosphorus-3d orbitals is invoked to explain the greater yield of the cis isomer of N₃P₃Cl₄(OAr)₂ than that of its trans isomer.     

The Reaction of Organoboranes with Trimethylsilyl Azide in a Neutral Medium: Synthesis of Primary Amines

A facile method for the preparation of primary amines using trimethylsilyl azide and trialXyl-boranes in a neutral protic solvent is described.     

Preparation of Vicinal Azidohydrins by Reaction of Oxiranes with Triethylaluminium/Hydrogen Azide

A novel, mild, and highly stereoselective transformation of epoxides to azidohydrins by treatment with Et₃Al/HN₃ in toluene is described. As an example for the versatility of the reaction, a polyfunctional compound, 14,15-epoxy-14,15-dihydromilbemycin D ( 1 ), was transformed to 14-azido-14,15-dihydro-15-hydroxymilbemycin D ( 2 ) in 61% yield.