Clay-Catalyzed Nitration of a Carbamate Fungicide Diethofencarb
摘要:
The unique nitration of the carbamate fungicide diethofencarb (Powmyl, isopropyl 3,4-diethoxycarbanilate) was examined in 14 Japanese soils and three types of clays under the aerobic conditions using the C-14-labeled compound. Nitration at the 6-position of the 3,4-diethoxyphenyl ring was a clay-catalyzed reaction and extremely enhanced under the dry conditions. Kinetic and product analysis on nitration of nine C-14-labeled carbamate analogues in the kaolinite thin layer showed the nitration proceeding electrophilically. Requirement of molecular oxygen and retardation of nitration by radical scavengers and spin-trap reagents together with semiempirical AM1 molecular orbital calculations strongly suggested contribution of a radical mechanism, and these different speculations on the reaction mechanism might originate from the heterogeneous reaction environment on clay.
developed methodology rendered the use of carboxylic acids as a direct surrogate of primary amines, for the synthesis of primary ureas, secondary/tertiaryureas, O/S-carbamates, benzoyl ureas, amides, and N-formyls, exploiting the Curtius reaction. This approach has a potential to provide a diversified library of N-containing compounds, starting from a single carboxylic acid, based on the selection of the
PdCl2 catalyzed efficient assembly of organic azides, CO, and alcohols under mild conditions: a direct approach to synthesize carbamates
作者:Long Ren、Ning Jiao
DOI:10.1039/c4cc00538d
日期:——
A simple and readily available PdCl2 catalyzed carbamate synthesis method via isocyanate generation and application in situ has been developed. This chemistry provides an efficient and practical approach to synthesize carbamates from simple organic azides, CO atmosphere and alcohols. The broad scope, mild and neutral conditions, and only N2 as the byproduct make this transformation very useful. Moreover, simple examples of modification of bioactive molecules and construction of macrocycles were achieved through this protocol.
Synthesis of Aryl Carbamates
<i>via</i>
Copper‐Catalyzed Coupling of Aryl Halides with Potassium Cyanate
作者:Xinye Yang、Yihua Zhang、Dawei Ma
DOI:10.1002/adsc.201200296
日期:2012.9.17
Coupling of aryl halides with potassiumcyanate takes place at 100–110 °C in alcohols under the catalysis of CuI (cuprous iodide) and 2‐(2,6‐dimethylphenylamino)‐2‐oxoacetic acid, affording the corresponding aryl carbamates with great diversity.
Reversible double insertion of aryl isocyanates into the Ti–O bond of titanium(IV) isopropoxide
作者:Rajshekhar Ghosh、Munirathinam Nethaji、Ashoka G. Samuelson
DOI:10.1016/j.jorganchem.2004.11.038
日期:2005.3
The insertion of phenyl isocyanate into titanium isopropoxide leads to the formation of a dimeric complex [Ti(OiPr)2(μ-OiPr)C6H5N(OiPr)CO}]2 (1) which has been structurally characterized. Reaction of titanium isopropoxide with two and more than 2 equiv. of phenyl isocyanate is complicated by competitive, reversible insertion between the titanium carbamate and titanium isopropoxide. The ligand formed
苯基异氰酸酯的插入异丙醇钛导致的形成的二聚复合物钛[Ti(O我PR)2(μ-O我PR)C 6 H ^ 5 N(0我PR)CO}] 2(1),其已经在结构上得到了表征。异丙醇钛与两个或大于2当量的反应 氨基甲酸钛和异丙醇钛之间竞争性,可逆的插入使异氰酸苯酯的合成变得复杂。通过将异氰酸苯基酯插入氨基甲酸钛中形成的配体已在结构上以其质子化形式C 6 H 5 N C(O i Pr)O} C(O)N(H)C进行了表征6 H 5(3aH)。动力学上有利于氨基甲酸酯的插入,而异丙醇中的热力学上有利的产物。
Copper-catalyzed carbonylation of anilines by diisopropyl azodicarboxylate for the synthesis of carbamates
been developed. The N–H bond cleavage and N–C bond formation were notably achieved under solvent-free conditions and a variety of carbamates were synthesized from readily available anilines using diisopropyl azodicarboxylate (DIAD) as the carbonylating source.