Evolution of carbonylation catalysis: no need for carbon monoxide

Progress in organometallic catalysis began with the discovery of the Roelen reaction (hydroformylation with carbon monoxide and hydrogen) in 1938 and the Reppe reaction (hydrocarboxylation with carbon monoxide and water) in 1939. Since then, carbonylation chemistry by using carbon monoxide has occupied a central position in organometallic chemistry, as it relates to organic synthesis. There is, however, the problem of using gaseous carbon monoxide (a toxic greenhouse gas) in this chemistry. Recently, some strategies that address this issue have appeared. This minireview describes carbonylation reactions that can be conducted without the direct use of carbon monoxide. These carbonylation reactions provide reliable and accessible tools for synthetic organic chemists.     

Dimethylformamide as a carbon monoxide source in fast palladium-catalyzed aminocarbonylations of aryl bromides

Dimethylformamide (DMF) acts as an efficient source of carbon monoxide and dimethylamine in the palladium-catalyzed aminocarbonylation (Heck carbonylation) of p-tolyl bromide to provide the dimethylamide. Addition of amines to the reaction mixture in excess delivers the corresponding aryl amides in good yields. The amines employed, benzylamine, morpholine, and aniline, all constitute good reaction partners. The reaction proceeds smoothly with bromobenzene and more electron-rich aryl bromides, but electron-deficient aryl bromides fail to undergo aminocarbonylation. The reactions are conducted at 180-190 degrees C for 15-20 min with microwave heating in a reaction mixture containing imidazole and potassium tert-butoxide: the latter is required to promote decomposition of the DMF solvent at a suitable rate. The beneficial effects of controlled microwave irradiation as an energy source for the rapid heating of the carbonylation reaction mixture are demonstrated. The carbonylation procedure reported herein, which relies on the in situ generation of carbon monoxide, serves as a convenient alternative to other carbonylation methods and is particularly applicable to small-scale reactions where short reaction times are desired and the direct use of carbon monoxide gas is impractical.     

Syngas reactions XII. The selective preparation of acetaldehyde,alkanols, esters and acetic acid from synthesis gas

Several classes of commercially important oxygenates, including acetaldehyde, ethanol, methyl acetate, ethyl acetate and acetic acid as well as C₁–C₃ alcohol/acetate ester mixtures, may each be selectivelygenerated from synthesis gas through the application of novel classes of ruthenium-containing bimetallic catalysts particularly those of ruthenium and cobalt (Ru? Co). A particular feature of these versatile catalysts is that all precursors are iodidefree. Products are formed through a combination of carbon monoxide hydrogenation, methanol homologation, methyl acetate homologation and methanol carbonylation reaction sequences.     

Carbonylations of Alkenes with CO Surrogates

Alkene carbonylation reactions are important for the production of value‐added bulk and fine chemicals. Nowadays, all industrial carbonylation processes make use of highly toxic and flammable carbon monoxide. In fact, these properties impede the wider use of carbonylation reactions in industry and academia. Hence, performing carbonylations without the use of CO is highly desired and will contribute to the further advancement of sustainable chemistry. Although the use of carbon monoxide surrogates in alkene carbonylation reactions has been reported intermittently in the last 30 years, only recently has this area attracted significant interest. This Minireview summarizes carbonylation reactions of alkenes using different carbon monoxide surrogates.     

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.     

一氧化碳参与不饱和烃类化合物羰基化反应的研究进展

不饱和烃类化合物的羰基化反应是指在过渡金属催化剂存在条件下, 将一氧化碳(CO)分子以羰基的形式插入到烯烃(或者炔烃)与不同的亲核试剂中, 合成更高附加值化学品的转化过程. 本文综合评述了羰基化反应合成高附加值化学品的重要性, 介绍了几种不同类型的羰基化反应(氢甲酰化反应、 氢酯化反应、 氢酰胺化反应和氢羧基化反应)在发展新型催化剂体系及高效合成目标产物方面的研究进展, 并对羰基化反应存在的问题及未来发展方向和趋势进行了展望.     

Palladium-Catalyzed Low Pressure Carbonylation of Allylic Alcohols by Catalytic Anhydride Activation

A direct carbonylation of allylic alcohols has been realized for the first time with high catalyst activity at low pressure of CO (10 bar). The procedure is described in detail for the carbonylation of E-nerolidol, an important step in a new BASF-route to (−)-ambrox. Key to high activities in the allylic alcohol carbonylation is the finding that catalytic amounts of carboxylic anhydride activate the substrate and are constantly regenerated with carbon monoxide under the reaction conditions. The identified reaction conditions are transferrable to other substrates as well.     

Synthesis of Acylphosphonates by a Palladium‐Catalyzed Phosphonocarbonylation Reaction of Aryl Iodides with Phosphites

Acylphosphonates are conveniently synthesized from aryl iodides by a palladium‐catalyzed reaction with dialkyl phosphites under an atmospheric pressure of carbon monoxide. The reaction demonstrates the first example of the use of phosphorus nucleophiles in related metal‐catalyzed carbonylation reactions.     

New approaches in radical carbonylation chemistry: fluorous applications and designed tandem processes by species-hybridization with anions and transition metal species

New approaches in radical carbonylation chemistry are described. We have successfully integrated tin mediated radical carbonylation chemistry into modern fluorous applications and separation techniques. We revealed that radical carbonylation reactions can be performed using fluorous tin mediators, such as fluorous tin hydride and fluorous allyltin reagents. Fine tuning of the reaction conditions resulted in a good efficiency equivalent to conventional tin mediators. The tedious procedure of removing organotin byproducts can be circumvented through the use of fluorous/organic liquid-liquid extraction or fluorous liquid-solid phase extraction with fluorous reverse phase silica (FRPS). Also described are newly developed tandem carbonylation reactions that are based on species hybridization approaches. Using a radical/anionic hybrid system based on zinc-induced one-electron reduction, we achieved a three-component coupling reaction consisting of 4-alkenyl iodides, carbon monoxide, and electron-deficient alkenes. We observed two types of annulations processes, namely [4 + 1](radical)/[3 + 2](anionic) and [5 + 1](radical)/[3 + 2](anionic), which lead to the production of bicyclo[3.3.0]octanols and bicyclo[3.2.1]octanols, respectively. We found a radical/palladium hybrid system to be useful in the construction of new cyclic systems that incorporate two or three molecules of carbon monoxide.     

Ruthenium- and rhodium-catalyzed direct carbonylation of the ortho C-H bond in the benzene ring of N-arylpyrazoles

The direct carbonylation of C-H bonds in the benzene ring of N-phenylpyrazoles via catalysis by ruthenium or rhodium complexes is described. The reaction of N-phenylpyrazoles with carbon monoxide and ethylene in the presence of Ru(3)(CO)(12) or Rh(4)(CO)(12) resulted in the site-selective carbonylation of the ortho C-H bonds in the benzene ring to give the corresponding ethyl ketones. A variety of functional groups on the benzene ring can be tolerated. N-Phenylpyrazoles have higher reactivities than would be expected, based on the pK(a) values of the conjugate acid of pyrazole. The choice of solvent for this reaction is significant, and N, N-dimethylacetamide (DMA) gives the best result.     

Photoinitiated free radical carbonylation enhanced by photosensitizers

[reaction: see text] The enhancing effect of several photosensitizers in photoinitiated radical carbonylation is demonstrated and applied to accelerate the synthesis of compounds labeled with short-lived 11C. With the sensitizers, the synthesis of [carbonyl-11C]esters and acids from alkyl iodides, [11C]carbon monoxide, alcohols, and water provided up to 75-85% decay-corrected radiochemical yields in 6-min reactions under mild conditions. Acetone was used as a sensitizer in preparing 13C-substituted 1,10-decanedicarboxylic acid from (13C)carbon monoxide.     

On the reactivity of surface methoxy species in acidic zeolites

The in situ preparation and isolation of surface methoxy species on acidic zeolites are followed by further investigations of their reactivity in heterogeneously catalyzed reactions. For the first time, the following solid-state NMR evidence for the high reactivity of surface methoxy species has been obtained: (i) Surface methoxy species react readily with ammonia on acidic zeolites at room temperature, by which methylamines and methylammonium cations are formed. (ii) The transformation of surface methoxy species to other alkoxy species can be achieved by the reaction of surface methoxy species and corresponding alkyl halides on acidic zeolites. (iii) Surface methoxy species react readily with hydrochloride, giving methyl chloride as the sole product. (iv) The classic Koch carbonylation reaction and Ritter reaction in solution can be performed with surface methoxy species on acidic zeolites. (v) Carbon monoxide and carbon dioxide are produced by the oxidation of surface methoxy species in the presence of oxygen. The stability and reactivity of surface methoxy species are discussed in comparison with other surface alkoxy species (> C(1) species).     

Carbon monoxide as a reagent: A report on the role of N-heterocyclic carbene (NHC) ligands in metal-catalyzed carbonylation reactions

This report is a focused and critical essay on the effectiveness of M–NHC catalysts in reactions that specifically utilize carbon monoxide as a C1-carbon source. NHC ligands are touted as excellent trialkylphosphine (PR₃) mimics and are purported to improve existing phosphine based catalysts. One premise for using NHCs is that the need for excess ligand could be obviated in certain reactions. If true, then reactions involving CO as a reagent should be improved when a M–NHC complex is employed. Herein is a compilation of results that feature CO as a reagent in reactions such as: hydroformylation, hydroaminomethylation, carbonylation of aryl halides, oxidative carbonylation of amino and phenolic compounds, and the copolymerization of alkenes and CO. The aim of the report is to highlight reactions in which the ancillary NHC ligand is beneficial, detrimental, ineffective, or inconclusive in promoting the desired chemistry.     

Investigation of the effect of carbon monoxide on the oxidative carbonylation of methanol to dimethyl carbonate over CuX and CuZSM-5 zeolites

Direct synthesis of dimethyl carbonate offers prospects for a “green chemistry” replacement to eliminate use of phosgene for polymer production and other processes. The carbonylation of methanol to produce dimethyl carbonate over Cu⁺X and Cu⁺ZSM-5 zeolites prepared by solid-state ion exchange has been investigated, focusing on the interaction of carbon monoxide with the Cu⁺ zeolites. The methanol carbonylation mechanism reported previously has been extended to account for carbon monoxide adsorption at high pressure. The comparison of the results obtained from Cu⁺X and Cu⁺ZSM-5 show that strong CO adsorption on the catalyst is not related to increased rate of dimethyl carbonate production. The rate limiting step for DMC production is best described as the Eley-Rideal reaction of gas-phase CO with surface methoxide.     

硒催化的乙二胺、乙醇胺和环胺的氧化羰基化反应

研究了以硒粉作催化剂,一氧化碳为羰基化试剂的乙二胺、乙醇胺和一些环胺的羰基化反应,考察了氧化剂对反应的影响。发现氧气是该反应较好的氧化剂,而没有氧化剂存在时,几乎没有羰基化反应发生。在硒／氧化剂体系存在下,乙二胺和乙醇胺这样一些分子内具有相邻两个亲基团物质的羰基化反应易趋向于分子内羰基化形成较为稳定的五元环产物,产率和选择性较高;而环胺如哌啶和吗啡啉的羰基化可生成相应的四取代脲产物。对反应机理进行     

Metal-mediate reactions based formal synthesis of triptonide and triptolide

A formal synthesis of triptolide and triptonide has been achieved based on metal-mediate reactions. Specially, Noyori’s ruthenium catalyzed enantioselective transfer hydrogenation, indium(III) catalyzed cationic polyene cyclization, palladium catalyzed carbonylation, rhodium catalyzed double bond migration, and palladium catalyzed ortho sp² C–H bond oxygenation reactions served as convenient entry points for the preparation of the tetracyclic building blocks and the C14 hydroxyl group.     

Synthesis of tetrahydrophthalazine and phthalamide (phthalimide) derivatives via palladium-catalysed carbonylation of iodoarenes

1,2,3,4-Tetrahydrophthalazin-1-one and 1,2,3,4-tetrahydrophthalazin-1,4-dione derivatives were synthesised in high (up to 85%) and low yields using 2-iodobenzyl bromide and 1,2-diiodobenzene as bifunctional substrates, respectively. Iodoarenes, carbon monoxide and various hydrazine derivatives as N-nucleophiles were used in a three-component palladium-catalysed cascade hydrazinocarbonylation. A similar palladium-catalysed reaction, the aminocarbonylation of 1,2-diiodobenzene, resulted mainly in the formation of two types of major products depending on the amine N-nucleophiles: the use of primary amines yielded N-substituted phthalimides in double carbonylation, while secondary amines react with one of the iodoarene functionalities affording the corresponding 2-iodobenzamides. Due to double carbon monoxide insertion at one or both iodoarene functionalities, ketocarboxamide-carboxamide or bis-ketocarboxamide derivatives could be isolated by the modification of the reaction conditions. Some mechanistic details of the ring-closure reactions and the conditions leading to side-products are also discussed.     

硒催化反应最新研究进展

价廉易得的非金属硒作催化剂不但具有良好的催化活化CO的性能及反应过程相转移催化特性, 而且能循环使用. 用Se/CO催化体系替代贵金属催化羰基化法及剧毒的光气法进行羰基化反应及用Se/CO/H2O催化体系进行高选择性的还原反应, 具有反应条件温和、原子经济性高、成本低、环境友好、路线简短、后处理方便等优点, 因而引起人们的广泛关注. 概述了近几年来硒催化羰基化反应和硒催化选择性还原反应的最新研究进展, 并对硒催化反应的发展趋势进行了展望.     

Transition metal-catalyzed cyclocarbonylation in organic synthesis

Cyclocarbonylation reactions proceed mainly by the coupling reactions of carbonylation components with cyclization components having an unsaturated π-electron bond, in the presence of transition metal compounds. The representative reactions are cyclocarbonylation of alkynes by carbon monoxide such as Pauson–Khand reactions, hetero Pauson–Khand reactions, cyclocarbonylation of alkynyl alcohols, cyclocarbonylation of alkynyl amines, cyclocarbonylative alkyne–alkyne coupling reactions, and reductive cyclocarbonylation of alkynes. The other reactions are cyclocarbonylation of alkenes by carbon monoxide such as alkene–alkene coupling reactions, cyclocarbonylation with aldehydes, ketones, amines or imines, cyclocarbonylation of alkenyl alcohols. Carbonylation via cyclometalation, carbonylative ring expansion reactions, cyclocarbonylation by aldehydes, carboxylic acids or carboxylic acid esters are also cyclocarbonylation reactions. These reactions are conveniently used for organic syntheses, especially, for the syntheses of pharmaceutical intermediates.     

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。