Silica chloride: An efficient promoter for oxidation of arylboronic acids to phenols

This work reports simple, highly efficient protocol for the oxidation of arylboronic acids. Various arylboronic acids were selectively and completely converted into their corresponding oxidized phenols using H₂O₂ as an oxidant in presence of catalytic amount of silica chloride. The results show that silica chloride is a suitable and efficient promoter for the oxidation of arylboronic acids. Heterogeneous catalyst, mild reaction conditions, easy availability of the reagent, easy work-up, excellent yield of corresponding phenols, short reaction time and broad substrate scope makes this protocol attractive and a practical alternative to the existing methods.     

Suzuki-Miyaura coupling of diarylmethyl carbonates with arylboronic acids: a new access to triarylmethanes

Suzuki-Miyaura coupling of diarylmethyl carbonates with arylboronic acids proceeded in the presence of [Pd(eta3-C3H5)Cl]2-DPPPent (1,5-bis(diphenylphosphino)pentane) catalyst, yielding a variety of triarylmethanes.     

Micellar system in copper-catalysed hydroxylation of arylboronic acids: facile access to phenols

Copper-catalysed oxidative hydroxylation of arylboronic acids was accomplished in water containing an amphiphilic surfactant, providing facile access to phenol derivatives.     

Palladium-imidazolinium carbene-catalyzed arylation of aldehydes with arylboronic acids in water

The catalytic arylation of aldehydes with arylboronic acids in only water was found to be achieved using the palladium/thioether-imidazolinium chloride system in good to excellent yields. This catalytic process showed high tolerance for a broad range of substrates, giving a variety of carbinol derivatives with 2.0-3.0 mol % of the catalyst.     

Rhodium-catalyzed carbonylative arylation of alkynes with arylboronic acids: an efficient and straightforward method in the synthesis of 5-aryl-2(5H)-furanones

5-Aryl-2(5H)-furanones can be synthesized by the Rh-catalyzed reactions of arylboronic acids with internal alkynes under a CO atmosphere.     

水促进的三组分PBM反应合成三级胺

首次报道了甲醛衍生的胺缩醛和芳基硼酸在水的促进下,可以在没有催化剂的条件下高效的合成三级胺.在此基础上建立了一种利用多聚甲醛,二级胺和芳基或杂环硼酸合成三级胺的高效合成方法.此反应条件温和,操作简单,具有很好的底物适应性,目标产物的收率最高可达93%.     

Copper-mediated N- and O-arylations with arylboronic acids in a continuous flow microreactor: a new avenue for efficient scalability

A continuous flow procedure has been elaborated for the copper(II)-mediated N- and O-arylation of a range of compounds with arylboronic acids using a commercial microreactor setup. The compounds could be continuously generated in good yields paving the way for efficient scalability.     

An efficient base-free N-arylation of imidazoles and amines with arylboronic acids using copper-exchanged fluorapatite

N-Arylation of imidazoles and amines with arylboronic acids was accomplished with copper-exchanged fluorapatite (CuFAP) in methanol at room temperature. The products N-arylimidazoles and N-arylamines were isolated in good to excellent yields. A variety of arylboronic acids were converted to the corresponding N-arylimidazoles and N-arylamines, demonstrating the versatility of the reaction.     

Cerium chloride-promoted nucleophilic addition of grignard reagents to ketones an efficient method for the synthesis of tertiary alcohols

In the presence of anhydrous cerium(III) chloride, Grignard reagents react with Ketones to afford addition products in high yields, even though the substrates are susceptible to abnormal reactions with Grignard reagents alone.     

A nickel precatalyst for efficient cross-coupling reactions of aryl tosylates with arylboronic acids: vital role of dppf

An air-stable and easy-to-handle nickel precatalyst, (9-phenanthrenyl)Ni(II)(PPh₃)₂Cl, was examined for the cross-coupling reactions of aryl tosylates with arylboronic acids. Under the optimized reaction conditions, the catalytic system tolerates a wide range of activated, neutral and deactivated substrates. The selectivity of this cross-coupling reaction towards aryl tosylates and arylboronic acids has been investigated. It is proposed that ligand 1,1′-bis(diphenylphosphino)ferrocene (dppf) plays a key role in the coupling by enforcing a cis geometry in key intermediates and the active Ni(0) species.     

Simple and efficient protocol for the synthesis of functionalized styrenes from 1,2-dibromoethane and arylboronic acids

[reaction: see text] A simple and efficient protocol for the preparation of functionalized styrenes is disclosed that employs the palladium-catalyzed cross-coupling reaction of arylboronic acids with vinyl bromide, generated in situ from 1,2-dibromoethane. The reaction is carried out under mild reaction conditions. Compared with the cross-coupling reactions usually employed to obtain vinylarenes, this protocol is very simple, overcomes the inconvenience of using of ethylene under pressure, and uses air-stable and widely available arylboronic acids instead of vinyl organometallic reagents.     

Organic reactions in water: an efficient method for the synthesis of 1,2,4-oxadiazoles in water

A simple and efficient process has been developed for the synthesis of 1,2,4-oxadiazoles in good yields through the reaction of amidoximes with anhydrides under catalyst-free conditions in water.     

Tandem radical decarboxylation-oxidation of amino acids: A mild and efficient method for the generation of N-acyliminium ions and their nucleophilic trapping

A convenient methodology for the synthesis of 2-substituted pyrrolidines from alpha-amino acids is described. A number of cyclic and acyclic alpha-amino acid derivatives have been prepared in order to test the scope and diastereoselectivity of this method. These substrates were treated with iodosylbenzene or (diacetoxyiodo)benzene (DIB) and iodine in order to generate the corresponding carboxyl radical, which evolves by loss of carbon dioxide to produce a carbon radical which in turn undergoes oxidation to an N-acyliminium ion. This postulated intermediate could be trapped inter- or intramolecularly by oxygen, nitrogen and carbon nucleophiles. In the case of carbon nucleophiles, a Lewis acid is required for the concomitant carbon-carbon bond formation. High yields and modest diastereoselectivities were obtained. The present methodology was applied to the synthesis of omega-amino aldehydes or hemiaminals 8-14, 2-aminopyrrolidine derivative 15, aminolactone derivative 16, and azasugar analogues 17 and 18. When carbon nucleophiles were used, alkaloid precursors such as 2-allyl- or 2-alkylpyrrolidines 19-23 and 25 were obtained.     

Bipyridyl-based diphosphine as an efficient ligand in the rhodium-catalyzed asymmetric conjugate addition of arylboronic acids to α,β-unsaturated ketones

Reactions of α,β-unsaturated ketones with excess arylboronic acids in the presence of a rhodium catalyst generated in situ from Rh(acac)(C₂H₄) and (S)-P-Phos in dioxane/water at 100°C gave high yields of the corresponding products in up to 99% ee.     

Chiral norbornadienes as efficient ligands for the rhodium-catalyzed asymmetric 1,4-addition of arylboronic acids to fumaric and maleic compounds

[reaction: see text] A rhodium-catalyzed asymmetric 1,4-addition of arylboronic acids to fumaric and maleic compounds has been developed. While phosphorus-based chiral ligands fail to induce high stereoselectivity, chiral norbornadiene ligands have proved to be uniquely effective to achieve high enantioselectivity in these 1,4-addition reactions.     

Microwave-promoted cross-coupling of acid chlorides with arylboronic acids: a convenient method for preparing aromatic ketones

Simple catalytic systems for cross-coupling reactions of acyl chlorides with arylboronic acids under microwave conditions were tested. Microwave irradiation facilitated the reaction course. Mild reaction conditions afford the symmetrical and unsymmetrical aryl ketones in reasonable to high yields within a short time. A wide range of substrates bearing an electron-donating or an electron-withdrawing substituent on aryl ring of acid chloride as well as on boronic acid were examined and high yields of ketones were produced.     

Efficient use of a surfactant for copper-catalyzed coupling reaction of arylboronic acids with imidazoles in water

Copper-catalyzed oxidative coupling of arylboronic acids with imidazoles in water was realized by using an amphiphilic surfactant. By choosing an appropriate surfactant, reactions of a variety of arylboronic acids proceeded smoothly under mild and base-free conditions, providing an efficient, practical, and greener method for the synthesis of N-arylimidazoles.     

Design and synthesis of thioether-imidazolium chlorides as efficient ligands for palladium-catalyzed Suzuki-Miyaura coupling of aryl bromides with arylboronic acids

The catalyst composed of 0.25-0.025 mol % of [Pd(allyl)Cl]₂ and 0.5-0.05 mol % of the thioether-imidazolium chloride 3c was proven to be efficient in the Suzuki-Miyaura cross-coupling reactions of aryl bromides with arylboronic acids.     

Rhodium-catalyzed addition of arylboronic acids to isatins: an entry to diversity in 3-aryl-3-hydroxyoxindoles

[reaction: see text] A general method for the catalytic 1,2-addition of aryl and alkenyl boronic acids to isatins is described using a rhodium(I)/triphenylphosphite catalyst. The application of this transformation allows the synthesis of a variety of 3-aryl-3-hydroxyoxindole building blocks in high yields. An enantioselective version of this reaction using a rhodium(I)/phosphoramidite system is also presented.     

Complementary diastereoselective reduction of cyclic gamma-keto acids: efficient access to trisubsituted gamma-lactones

Complementary reduction conditions have been identified that provide ready access to each respective diastereomer of bi- and tricyclic, trisustituted gamma-lactones starting from the corresponding cyclic gamma-keto acids. Subjection of cyclic gamma-keto acids to silane reagents in the presence of trifluoroacetic acid provides all syn-gamma-lactones, while reduction with trialkylborohydrides furnishes the syn,anti-gamma-lactones. The conditions are mild and provide the product lactones in good yields and modest to excellent selectivity.