An extraordinarily efficient hybrid acids‐assisted, palladium‐catalyzed and chelating‐group‐assisted C H bond activation of N‐sulfonyl‐2‐aminobiaryls and their annulations with [60]fullerene via sequential C C and C N bond formation at room temperature to afford [60]fulleroazepines is demonstrated. The formation of [60]fulleroazepines is highly regioselective and tolerant to both electron‐withdrawing and electron‐donating groups on the aryl moiety and the reaction gives monofunctionalized fullerenes in good yields (up to 54% isolated yield and 92% based on converted C60). 相似文献
The last decades have seen a tremendous expanse in the application of C H activation of many different substrate classes, including the invaluable indole scaffold. Following the exciting emergence of C H activation as a multi‐faceted platform for functionalization, a versatile tool box has been developed for the preparation of structurally diverse indoles. This review article discusses recent advances and strategies for transition metal‐catalyzed C H activation of indoles.
Palladium‐catalyzed coupling reactions have become a central tool for the synthesis of biologically active compounds both in academia and industry. Most of these transformations make use of easily available substrates and allow for a shorter and more selective preparation of substituted arenes and heteroarenes compared to non‐catalytic pathways. Notably, molecular‐defined palladium catalysts offer high chemoselectivity and broad functional group tolerance. Considering these advantages, it is not surprising that several palladium‐catalyzed coupling reactions have been implemented in the last decade into the industrial manufacture of pharmaceuticals and fine chemicals. In this review different examples from 2001–2008 are highlighted, which have been performed at least on a kilogram scale in the chemical and pharmaceutical industries. 相似文献
A novel approach for C N bond formation was developed by iron‐catalyzed C C bond cleavage. Anilines and sulfonamides reacted smoothly with 2‐substituted 1,3‐diphenylpropane‐1,3‐diones to afford N‐alkylation products, in which the 1,3‐dicarbonyl group acts as a leaving group in the presence of an iron catalyst. The reversible C C bond cleavage plays a driving force to give the thermodynamically stable products. The method is complementary to the previous methods for C N bond formation. 相似文献
The implementation of selective, energy efficient, direct alkane oxidation chemistry could lead to a new paradigm in materials and energy technologies for the 21st century that is environmentally and economically superior to current processes. Such processes would allow the vast reserves of natural gas to be directly employed as feedstocks for fuels and chemicals. Molecular catalysts that activate and functionalize the C H bonds of unactivated hydrocarbons are of particular interest, from both a scientific and economic viewpoint. This results from the unique properties of these engineered materials, which allow them to carry out oxidative hydrocarbon functionalization, with high atom and energy efficiency, under relatively mild conditions. Despite the large body of work on the activation of C H bonds over the last three decades, relatively few catalyst systems based on this approach present a viable route to functionalize hydrocarbons. This dilemma is largely due to the large gaps in our fundamental knowledge to allow rational design of such catalysts. Addressed in this paper are some of the key challenges and approaches to the de novo design of alkane functionalization molecular catalysts based on the C H activation reaction, with an emphasis on our own research. 相似文献
The molecular iodine‐catalyzed three‐component reaction of amides or amide derivatives, paraformaldehyde and styrenes allows for the clean generation of allylamine derivatives in good yields and high regioselectivities. The reaction, forming water as the sole co‐product, is an experimentally easy to conduct transformation in the absence of transition metals under mild conditions. 相似文献
The allylation of 1,3‐dicarbonyl compounds and malononitrile with aliphatic allylic substrates is achieved under mild conditions in the presence of new ruthenium catalysts. The ruthenium complex [Ru(C5Me5)(2‐quinolinecarboxylato)(CH2CHCH‐n‐Pr)] [BF4] as a precatalyst, allows the synthesis of mono‐allylated branched derivatives. On the other hand, the parent complex [Ru(C5Me5)(MeCN)3] [PF6] as a precatalyst, straightforwardly favours the bis‐allylation of the procarbonucleophiles leading to bis‐allylated bis‐linear products. The involvement of the two precatalysts provides a sequential synthesis of unsymmetrical mixed linear‐branched bis‐allylated derivatives. 相似文献
A catalytic synthesis of selectively substituted phenanthridines is achieved through a reaction sequence involving palladium/norbornene‐catalyzed unsymmetrical aryl‐aryl and Heck couplings followed by aza‐Michael and retro‐Mannich reactions. In spite of the many steps involved the method is very simple and allows the formation of selectively substituted phenanthridines under mild conditions in a straightforward one‐pot reaction starting from readily available aryl iodides and bromides. 相似文献
New chiral phosphoramidites with an amide moiety were used for iridium‐catalyzed asymmetric allylic alkylation reactions. The best results were obtained with a ligand bearing an oxazolidinone moiety. The reaction of cinnamyl acetate with diethyl sodiomalonate without the use of lithium chloride gave the branched product with 94% ee. 相似文献
The cross‐couplings of alcohols to alkenes with the palladium/Lewis acid system are reported. This reaction occurs in a successive alkene dimerization, direct C H activation of alcohol and sp3 sp3 bond forming sequence via an interesting domino process. 相似文献
N‐tert‐Butoxycarbonyl azide (BocN3) was shown to be an efficient and economic source for the directed introduction of N‐Boc protected amino groups into the thiophene and benzene nucleus. Yields for the amination of 2‐pyridin‐2‐ylthiophenes (10 examples) were 52–88%. For the amination of the respective benzenes (10 examples) yields between 54% and 99% were recorded with an improved reactivity observed for substrates that bear an electron‐withdrawing group. The reaction was applied to short total syntheses of the indoloquinoline alkaloids quindoline and cryptolepine. The facile removal of the Boc protecting group was the key to the success of the syntheses. The scope of the reaction was extended to a C(sp3) H bond amination and to the amination of 2‐phenyloxazoline. For the amination of 2‐pyridin‐2‐ylbenzene a kinetic deuterium isotope effect of 2.0 was determined.
An in‐depth mechanistic study on the palladium‐catalyzed direct arylation of imidazoles at the C‐5 position is presented. The interactions of triphenylphosphine (PPh3)‐ligated aryl‐Pd species with 1,2‐dimethyl‐1H‐imidazole (dmim) have been studied in detail. In contrast with previous suggestions, phosphine‐ligated organo‐Pd species are not active and the reaction proceeds through imidazole‐ligated organo‐Pd intermediates. The kinetics of the oxidative addition of aryl halides with dmim‐ligated Pd(0) species have been characterized in a Pd(dba)2/dmim model system. A thorough study of the equilibria involving novel [ArPd(dmim)2X] complexes (X=I, OAc) and the unexpected cationic [ArPd(dmim)3]+ is also reported. The ability of these species to effect the C H arylation of dmim at room temperature in the presence of acetate is also demonstrated.
It appears that transition metal catalysts are not necessary to perform the direct arylation of electron‐rich heterocycles with aryl iodides and bromides. Lithium tert‐butoxide in DMF promotes this reaction for a variety of N‐alkyl‐ and N‐arylpyrroles as well as for benzofuran and some other electron‐rich aromatic compounds and provides the desired products in moderate to high yields. In contrast to all previous reports on the Pd‐catalyzed direct arylation of indolizine, the reaction mediated by lithium tert‐butoxide proceeds selectively at position 5. 相似文献
Pyrroles, ubiquitous bioactive heterocycles in nature, are readily prepared via a palladium‐catalyzed oxidative annulation of cyclic trans‐enamines to various internal alkynes in the absence of a directing group.
Zinc is the 24th most abundant element in the Earth’s crust. Since the discovery of pure zinc metal in the 18th century, the main application of zinc metal is as materials. Because zinc salts are abundant, cheap, non‐toxic, and exhibit environmentally benign properties, organic chemists have been interested in using zinc salts as catalysts in organic synthesis during the last three decades. Within this review, we have summarized the progress on applications of zinc salts in organic reactions. Our the target is to emphasize the special properties of zinc catalysts, and further promote the interest of organic chemists. 相似文献
An organocatalytic, enantioselective conjugate addition reaction of nitroalkanes with nitroolefins has been developed under neat conditions without using an organic solvent. The process, catalyzed by a modified Cinchona alkaloid, affords synthetically useful 1,3‐dinitro compounds in good yields (70–82 %) with good degrees of enantioselectivity (67–88 % ee). 相似文献
Nine types of diversely fused heterocyclic quaternary ammonium salts were constructed through an oxidative C H annulation reaction. Both high‐valent pentamethylcyclopentadienylcobalt(III) and pentamethylcyclopentadienyliridium(III) were found to be effective as catalyst for this reaction. Broad substrate scope and good functional group tolerance were observed.
An efficient oxidative cross‐coupling reaction between 1,3‐diarylpropenes and indoles in the presence of palladium chloride was achieved with 2,3‐dichloro‐5,6‐dicyanoquinone (DDQ) as oxidant. The reaction afforded 1,3‐diphenylallylindoles in moderate to high yields under mild conditions, thus providing a novel methodology to synthesize the respective products. 相似文献
