非对称取代脲的合成与应用

总结了合成非对称取代脲的几种方法，分析了各种方法的利弊，介绍了非对称 取代脲的主要应用，指出直接利用一氧化碳进行硒催化的胺与硝基化合物的氧化还 原羰基化反应来合成非对称取代脲的方法是比较有发展前景的方法，并对硒催化的 氧化还原羰基化反应作了较为详细的介绍。     

尿素羰基化作用研究进展

综述了尿素作为羰基化试剂合成氨基酸酯或碳酸酯类化合物及脲类化合物的研究进展,详细讨论了合成反应中所涉及的催化剂、反应机理和工艺条件,指出通过尿素醇解或胺解反应合成相应化合物是一条绿色工艺路线,具有广阔应用前景.     

硒催化的邻硝基苯胺类化合物的羰基化反应

用硒作催化剂，三乙胺为助催化剂，CO为羰基化试剂，通过氧化还原羰基化的方法，将邻硝基苯胺类化合物在分子内羰基化成环，反应生成相应的一系列环脲类物质，此催化合成方法的反应选择性近秋100％，收率较高，操作简单，并提出了可能的反应机理。     

氨基甲酸酯类化合物的合成进展

作为一类重要的精细化学品,氨基甲酸酯类化合物在农药、医药及有机合成等领域有着广泛的应用。本文介绍了氨基甲酸酯类化合物的主要合成方法,重点阐述了光气及其衍生物法、羰基化法、二氧化碳法、脲类化合物醇解法、霍夫曼重排法等一系列合成途径,并对各合成方法进行了分析评价。指出硒催化硝基化合物及胺等含氮化合物与醇在一氧化碳存在下经羰基化反应来合成氨基甲酸酯类化合物的方法具有较好的发展前景。     

钯催化烯烃的不对称马氏氢胺羰基化反应

一氧化碳参与的羰基化反应是有机合成中最重要的反应之一.烯烃的氢羰基化反应已经被广泛应用于药物、材料及精细化学品的工业生产中[1].例如,乙烯的甲氧羰基化反应被用于甲基丙烯酸甲酯的工业合成,然而,该领域仍有许多挑战性难题尚未得到有效解决.烯烃的氢胺羰基化反应能以原子经济性的方式合成酰胺,且已经实现该类反应的区域选择性控制,但是,如何同时控制该类反应的区域选择性和对映选择性,以简单易得的烯烃和一氧化碳为底物直接合成手性酰胺类化合物,仍是一个悬而未决的重要难题.     

硒催化4-氨基吡啶与硝基芳烃羰基化合成4-吡啶基脲

以非金属硒为催化剂,三乙胺为助催化剂,用CO替代剧毒光气作为羰基化试剂,通过鼓泡方式经硒催化"一锅煮"的4-氨基吡啶与硝基芳烃的氧化还原羰基化反应合成4-吡啶基脲.通过探究反应温度、反应时间、溶剂及碱的种类等因素的影响,获得了反应的优化条件.在优化条件的基础上,以中等到良好的收率制得4-吡啶基脲类化合物,反应底物硝基芳烃的普遍适用性较好;还提出了该反应的可能机理.     

催化选择氧化还原羰基化合成脲*

本文概述了胺硝基物选择氧化还原羰基化生成脲的新工艺路线。对催化剂体系、羰基化反应机理和反应的选择性作了比较全面的评述,着重介绍了金属钯和非金属硒催化的选择氧化还原羰基化反应合成对称脲、非对称脲和环脲,讨论了该方法的应用前景。     

高分子负载钯基双金属催化苯胺氧化羰基化反应

芳香族氨基甲酸酯(ArNHCO₂R)是制备芳基异氰酸酯(ArNCO)的重要中间体,其合成通常需用光气与芳胺反应,且生成大量HCl.因此,人们致力于发展一些无需光气参与的反应过程,如催化芳胺氧化羰基化生成芳氨基甲酸酯.     

钯催化芳基偶氮的氧化羰基化反应

采用TBHP作为氧化剂,发展了钯催化芳基偶氮化合物N＝N双键断裂的氧化羰基化反应.芳基偶氮的羰基化反应在Pd(OAc)2(5％),MeO-BIPHEP (5％),芳基偶氮(0.2 mmol),TBHP(2 equiv),H2O(1 equiv),DCE(1 mL),CO (3.0 MPa)的条件下110℃反应12h后,经柱层析纯化分离得到31％-91％的芳基脲.初步的机理研究表明,芳基偶氮化合物的N＝N双键断裂原位产生芳基胺,再进一步氧化羰基化生成芳基脲.     

钯催化芳基偶氮的氧化羰基化反应（英文）

采用TBHP作为氧化剂,发展了钯催化芳基偶氮化合物N=N双键断裂的氧化羰基化反应.芳基偶氮的羰基化反应在Pd(OAc)2(5%),MeO-BIPHEP(5%),芳基偶氮(0.2 mmol),TBHP(2 equiv),H2O(1 equiv),DCE(1 mL),CO(3.0 MPa)的条件下110℃反应12 h后,经柱层析纯化分离得到31%-91%的芳基脲.初步的机理研究表明,芳基偶氮化合物的N=N双键断裂原位产生芳基胺,再进一步氧化羰基化生成芳基脲.     

Efficient synthesis of ureas by direct palladium-catalyzed oxidative carbonylation of amines

A general synthesis of symmetrically disubstituted ureas and trisubstituted ureas by direct Pd-catalyzed oxidative carbonylation of primary amines or of a mixture of a primary and a secondary amine, respectively, with unprecedented catalytic efficiencies for this kind of process, is reported. Reactions are carried out at 90-100 degrees C in DME as the solvent in the presence of PdI(2) in conjunction with an excess of KI as the catalytic system and under 20 atm of a 4:1 mixture of CO and air. In some cases, working in the presence of an excess of CO(2) (40 atm) in addition to CO and air (60 atm total) had a beneficial effect on substrate reactivity and product yield. Cyclic five-membered and six-membered ureas were easily formed from primary diamines. The methodology has been successfully applied to the synthesis of pharmacologically active ureas, such as those deriving from alpha-amino esters or urea NPY5RA-972, a potent antagonist of the neuropeptide Y5 receptor.     

非光气含氮化合物催化羰化研究进展

本文对近几年来非光气含氮化合物羰化合成氨基甲酸酯及二取代脲的方法进行了概述,主要包括使用钯、钌、铑、硒、金等催化体系以一氧化碳为羰化剂进行的催化氧化羰化和催化还原羰化反应过程,以及使用碱催化体系以二氧化碳和碳酸二甲酯等为羰化剂的反应过程和机理.     

Oxidative carbonylation reactions: organometallic compounds (R-M) or hydrocarbons (R-H) as nucleophiles

Oxidative carbonylation reactions have attracted broad interest from both academia and industry in recent years. Enormous efforts have gone into the syntheses of carbonate and urea derivatives through the oxidative carbonylation of alcohols and amines. Very recently, organometallic reagents (R-M) and hydrocarbons(R-H) were directly employed as nucleophiles to construct a C-C bond in oxidative carbonylation reactions. This Minireview summarizes this novel type of oxidative carbonylation reaction.     

Active control of methanol carbonylation selectivity over Au/carbon anode by electrochemical potential

Electrochemical oxidative carbonylation of methanol was studied over Au supported carbon anode in CO. The major carbonylation products were dimethyl oxalate (DMO) and dimethyl carbonate (DMC). The minor oxidation products were dimethoxy methane (DMM) and methyl formate (MF) from methanol and CO(2). Influences of various reaction conditions were studied on carbonylation activities and selectivities. The selectivities to DMO and DMC can be controlled by the electrochemical potential. Electrocatalysis of Au/carbon anode was studied by cyclic voltammetry (CV), stoichiometric reactions among Au(3+), methanol, and CO, and UV-vis spectra. The Au/carbon anode was characterized by XRD, SEM, and BE images before and after the carbonylation. These experimental facts strongly suggest that transition of oxidation states of Au affects changing of the carbonylation selectivities to DMO and DMC. Au(0) is the active species for the selective DMO formation by direct electrochemical carbonylation at low potentials (<+1.2 V (Ag/AgCl)). On the other hand, Au(3+) is the active spices for the selective DMC formation by indirect electrochemical carbonylation through Au(3+)/Au(+) redox at high potentials (>+1.3 V).     

双齿氮配体钯配合物催化的羰化反应研究

研究了双齿氮配体钯（II）配合物催化剂（1-3）在对邻溴碘苯与胺的羰化合成酰胺反应以及炔烃的氧化羰化制备炔酸酯反应中的催化性能,考察了不同条件下催化剂的催化活性并对其反应产物进行了表征.研究结果表明该催化剂在酰胺化合成氮取代邻苯二甲酰亚胺的反应中表现出了较好的催化活性和选择性,分离收率和选择性高达88%和85%;在芳基...     

Catalytic oxidative carbonylation of primary and secondary diamines to cyclic ureas. Optimization and substituent studies

W(CO)(6)-catalyzed oxidative carbonylation of 1,3-propanediamine to the corresponding urea has been examined under a variety of conditions. Following optimization, the Thorpe-Ingold effect on ring closure was studied using 2,2-dialkyl-1,3-propanediamines. For the 2,2-dimethyl- and 2,2-dibutyl-1,3-propanediamines, the yields were increased significantly as compared to that of the unsubstituted case. The eight-membered cyclic urea 5-butyl-5-ethyl-1,3-diazepan-2-one (5f) was formed in 38% yield, while only trace amounts of the cyclic urea were produced from the parent 1,5-pentanediamine. In a study of secondary diamines, yields from the carbonylation of N,N'-dialkyl-2,2-dimethyl-1,3-propanediamines were lower than those obtained from the primary diamines. The main byproducts from secondary diamines were tetrahydropyrimidine derivatives formed from a competitive reaction of the substrate with the oxidant and base.     

DFT computational study of the mechanism of allyl halides carbonylation catalyzed by nickel tetracarbonyl

A theoretical investigation at the DFT(B3LYP) level on the carbonylation reaction of allyl bromide catalyzed by nickel tetra-carbonyl Ni(CO)(4) is discussed. The computational results show the following: (i) Three main steps characterize the catalytic cycle: (a) an oxidative addition step, (b) a carbonylation step, and (c) a reductive elimination step where the acyl product is obtained and the catalyst is regenerated. (ii) Both Ni(CO)(3) and Ni(CO)(4) complexes can behave as "active" catalytic species. (iii) The oxidative addition leads to the formation of either eta(3) or eta(1)-allyl nickel complexes, which are involved in a fast equilibrium. (iv) The carbonylation occurs much more easily on the eta(1) than on the eta(3) intermediates.     

Synthesis of 2‐Alkynoates by Palladium(II)‐Catalyzed Oxidative Carbonylation of Terminal Alkynes and Alcohols

A homogeneous Pd^II catalyst, utilizing a simple and inexpensive amine ligand (TMEDA), allows 2‐alkynoates to be prepared in high yields by an oxidative carbonylation of terminal alkynes and alcohols. The catalyst system overcomes many of the limitations of previous palladium carbonylation catalysts. It has an increased substrate scope, avoids large excesses of alcohol substrate and uses a desirable solvent. The catalyst employs oxygen as the terminal oxidant and can be operated under safer gas mixtures.     

Pd(OAc)2-catalyzed carbonylation of amines

A phosphine-free catalytic system [Pd(OAc)2-Cu(OAc)2-air] induced a substrate-specific carbonylation of amines in boiling toluene under CO gas (1 atm). Symmetrical N,N'-dialkylureas were obtained by the carbonylation of primary amines. N,N,N'-Trialkylureas were selectively formed by addition of a secondary amine to the above reaction vessel. Secondary amines did not give tetraalkylureas. However, dialkylamines with a phenyl group on their alkyl chains, such as N-monoalkylated benzylic amine or phenethylamine derivatives, underwent a direct aromatic carbonylation to afford five- or six-membered benzolactams. In the carbonylation, the chelation effect or steric repulsion between Pd(II) and the meta-substituent in the ortho-palladation and the ring sizes of cyclopalladation products that were formed prior to carbonylation were found to generate good site selectivity and increase the reaction rate. In contrast, carbonylation of omega-arylalkylamines with a hydroxyl group gave neither ureas nor benzolactams but instead produced 1,3-oxazolidinones smoothly. Hydrochlorides of amines also underwent carbonylation to afford the corresponding amides under the conditions used. This procedure made it possible to prepare ureas of amino acid esters and N-alkylcarbamates in practical yields.