Iron-catalyzed oxidative coupling of arylboronic acids with benzene derivatives through homolytic aromatic substitution

Fe(OTf)(3)-1,10-phenanthroline catalyzes oxidative coupling of arylboronic acids with benzene derivatives using t-BuOOt-Bu as an oxidant. The reaction proceeds through homolytic aromatic substitution with aryl radicals generated from arylboronic acids and t-BuO˙.     

Iodine-catalyzed Friedel-Crafts alkylation of electron-rich arenes with aldehydes: efficient synthesis of triarylmethanes and diarylalkanes

Iodine is shown to be an efficient catalyst for the Friedel-Crafts alkylation of arenes with a wide variety of aldehydes in toluene under ‘open-flask’ and mild conditions. In the presence of 10 mol % of iodine, the reaction of arenes with aromatic aldehydes gives the corresponding triarylmethane derivatives (TRAMs), regioselectively, in good to excellent yields. On the other hand, a series of diarylalkane derivatives is synthesized smoothly by the reaction with aliphatic aldehydes.     

Iridium-catalyzed carbonyl group-directed oxidative coupling of arenes with alkenes

The iridium complex [Cp¹IrCl₂]₂ is a good catalyst for the directed oxidative coupling of arenes with alkenes; a wide range of carbonyl functionalities (NHCOR, CONH₂ and COR) can be employed as the directing group.     

Ru-catalyzed aerobic oxidative coupling of arylboronic acids with arenes

A Ru-catalyzed oxidative coupling of arenes with boronic acids using molecular oxygen via direct C-H activation is reported. Both the scope and the mechanism of the process are discussed.     

Visible light induced oxidative coupling of purines with arenes

The photocatalyzed synthesis of 9-arylpurines has been developed using 9H-purines and non-activated arenes. This method is highly atom economical using an acridinium photocatalyst induced by visible light under air atmosphere at room temperature. It employs no metal or external oxidant for the synthesis of 9-arylpurine derivatives.     

Friedel-Crafts alkylation of indoles with trichloroacetimidates

Substituted indole scaffolds are often utilized in medicinal chemistry as they regularly possess significant pharmacological activity. Therefore the development of simple, inexpensive and efficient methods for alkylating the indole heterocycle continues to be an active research area. Reported are reactions of trichloroacetimidate electrophiles and indoles to address the challenges of accessing alkyl decorated indole structures. These alkylations perform best when either the indole or the imidate is functionalized with electron withdrawing groups to avoid polyalkylation.     

Friedel-Crafts alkylation of indoles

The alkylation of indole and 2-methylindole with alkyl halides in the presence of a complex catalyst — dipyridinezinc chloride — was investigated. Nitromethane was used as the solvent. 3-Alkylindoles were obtained in 30–80% yields in all cases. The reaction mechanism is discussed. Data from the PMR and mass spectra are presented.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 921–924, July, 1978.     

Concise synthesis of aryl-C-nucleosides by Friedel-Crafts alkylation

A fast and simplified synthesis of 1',2'-dideoxy-1'-pyrenyl-riboside and several other C-nucleosides is shown. Shelf-stable 1-O-methyl-3,5-di-O-toluoyl-2-deoxyribose is demonstrated to serve as a versatile glycosyl donor in Lewis acid promoted Friedel-Crafts alkylations of unsubstituted pyrene and other inexpensive arenes such as fluorene and methylnaphthalene. The reaction conditions favour the formation of beta-configurated C-nucleosides which renders additional epimerisation steps unnecessary. As a result, protected beta-aryl-C-nucleosides are available directly from non-substituted arenes in three steps overall.     

Gold-catalyzed direct oxidative coupling reactions of non-activated arenes

A general gold-catalyzed oxidative homo- and hetero-coupling of arenes in mild conditions is described. This reaction gives moderate to excellent yield using PhI(OAc)₂ as an oxidant. The effects of temperature, solvent, oxidant and concentration of substrate in this process have also been studied in detail. The product identity and distribution as well as the substrate limitation give us insights into this type of gold catalysts. Depending upon the reaction conditions, the gold catalyst behaves as a simple Lewis acid, which produces amines from arenes using DIAD as an aminating reagent.     

Iron-catalyzed alkylation of alkenyl Grignard reagents

The first iron-catalyzed cross-coupling reaction between alkenyl Grignard reagents and n- or s-alkyl bromides is described. The reaction is stereoselective and takes place in the presence of 5 mol % of [Fe(acac)3/TMEDA/HMTA] (1:2:1) under very mild conditions (THF, 0 degrees C, 45 min).     

Samarium triflate-catalyzed halogen-promoted Friedel-Crafts alkylation with alkenes

A versatile and efficient halogen-promoted highly regio- and stereoselective Friedel-Crafts (F-C) alkylation with alkenes has been developed with use of easily available and inexpensive NBS or I2 as the efficient halogen sources. Lewis acids, in particular metal triflates, are found to be effective catalysts for this halogen-promoted F-C alkylation. Among these, Sm(OTf)3 was the best catalyst. Electron-rich arenes smoothly underwent F-C alkylation with a variety of alkenes including alpha,beta-unsaturated carbonyl compounds.     

Diastereoselective Friedel-Crafts alkylation of hydronaphthalenes

An efficient and versatile synthesis of chiral tetralins has been developed using both inter- and intramolecular Friedel-Crafts alkylation as a key step. The readily available hydronaphthalene substrates were prepared via a highly enantioselective metal-catalyzed ring opening of meso-oxabicyclic alkenes followed by hydrogenation. A wide variety of complex tetracyclic compounds have been isolated with high levels of regio-, diastereo-, and enantioselectivity.     

A general gold-catalyzed direct oxidative coupling of non-activated arenes

A gold-catalyzed mild and general oxidative homo-coupling of arenes using PhI(OAc)2 as the oxidant is described (13 examples, 31-81% yield).     

阴离子相转移催化的Friedel-Crafts烷基化反应

提出三种阴离子表面活性剂十二烷基苯磺酸钠、十二烷基磺酸钠、十二烷基硫酸钠作为阴离子相转移催化剂特性。研究了它们在Friedel-Crafts反应中的催化性能,结果表明它们都有良好的催化特性合成了七个化合物, 其中五个为未见文献报导的新化合物, 它们是二苯甲基萘酚和二苯甲基酚类化合物。     

Diastereoselective intramolecular Friedel-Crafts alkylation of tetralins

An efficient and versatile synthesis of cis-hexahydrobenzophenanthridines starting from readily available tetralins has been developed using an intramolecular Friedel-Crafts alkylation as a key step. The substrates were prepared via a highly stereocontrolled rhodium-catalyzed ring-opening reaction of meso-oxabicyclic alkenes and a hydrogenation sequence. Thus, a wide variety of complex tetracyclic compounds have been isolated with a high level of regio-, diastereo-, and enantioselectivity.     

Organocatalytic enantioselective Friedel-Crafts alkylation of simple phenols with trifluoropyruvate

Enantioselective Friedel-Crafts alkylation of simple phenols (4a-j) with 3,3,3-trifluoropyruvate (3) was accomplished by using chiral cinchona alkaloid catalyst 2h (10 mol %). High yields and enantioselectivities (71-94% ee) of the Friedel-Crafts alkylation products were obtained.     

One-pot access to indolylchromeno[2,3-b]indoles via iodine-mediated Friedel-Crafts alkylation/oxidative coupling reaction of indoles and salicylaldehydes

An I₂-mediated Friedel-Crafts alkylation/oxidative coupling reaction of indoles and salicylaldehydes was developed. With the developed protocol, a series of indolylchromeno[2,3-b]indoles were obtained in good yields (up to 88%) under mild reaction conditions. Two possible reaction mechanisms were tentatively brought forward to account for the formation of the products in light of some control experiments.     

Uncatalyzed Friedel-Crafts alkylation of aromatic compounds through reactive benzyl cations generated from N-sulfamoylcarbamates

[reaction: see text] A new method for the generation of highly reactive benzyl cations by thermal decomposition of aryl-benzyl-sulfamoylcarbamates, obtained in a one-pot reaction from chlorosulfonyl isocyanate, is described. The generated cations alkylate aromatic compounds efficiently in the absence of catalysts.