Reaction Of Boronic Acids Research Articles

ChemInform Abstract: Regioselective Cross‐Coupling Reactions of Boronic Acids with Dihalo Heterocycles.

AbstractIt is found that K2CO3/Pd2dba3‐mediated treatment of the dichloro acid (I) with boronic acids allows selective formation of 2‐arylated derivatives like (III).

An approach to enzyme inhibition employing reversible boronate ester formation

Dynamic combinatorial chemistry (DCC) is a potentially useful method for the identification of biomacromolecule ligands; however, the number of reactions applicable to DCC in aqueous solution is limited. We report studies that investigate the reversible reaction of boronic acids with alcohols as an approach to enzyme inhibition, employing α-chymotrypsin as a model system. NMR techniques (11B NMR and 1H waterLOGSY) were used to observe ternary complexes of boronic acids, sugars and α-chymotrypsin, and were useful for distinguishing preferentially binding combinations of boronic acids and sugars. The results reveal that both the propensity of boronate ester formation in solution and affinity of the boronate ester for the target enzyme determine whether ternary complex formation is observed. The results also provide proof of principle for the boronate ester approach to DCC versusprotein targets.

Boron-containing inhibitors of synthetases

The use of boron in small-molecule pharmaceuticals is increasing. Boron's ubiquitous occurrence in nature and the recent success of a boronic acid drug (Velcade®) in the clinic have alleviated many concerns over its use in pharmaceuticals. In addition, the unique physicochemical properties of boronic acids make them an attractive addition to the medicinal chemists toolbox. This tutorial review will discuss these properties and potential benefits for anyone interested in finding novel enzyme inhibitors. An exceptional class of boronic acids, the oxaboroles, will be highlighted and their properties and uses will be discussed in detail. Finally, the current paradigm for the reaction of boronic acids with enzyme nucleophiles will be summarized.

Palladium-Catalyzed Synthesis of Aryl Ketones from Carboxylic Acids and Arylboronic Acids Using EEDQ

with boronic acids or other organoboranes. These methods are mild, efficient, and regioselective. However, there are several limitations of these methods. The acid derivatives are not commercially available and anhydride is inefficient to use because the half part of car-boxylic anhydride is lost as a leaving group. Goosen and his coworkers reported a palladium-catalyzed synthesis of aryl ketones directly by the reaction of boronic acids with active ester or anhydride of carboxylic acid generated

Regioselective Cross-Coupling Reactions of Boronic Acids with Dihalo Heterocycles

The carboxylic acid anion moiety has been used as a tunable directing group in the cross-coupling reaction of 2,6-dichloronicotinic acid and 2,5-dibromo-1,2,4-triazole derivatives producing selectively the 2- or 6-substituted nicotinic acids, while only the 5-substituted triazoles were obtained under a variety of conditions.

ChemInform Abstract: Copper‐Promoted N‐Cyclopropylation of Anilines and Amines by Cyclopropylboronic Acid.

AbstractA series of N‐cyclopropyl derivatives is readily prepared by copper‐catalyzed reaction of boronic acid (II) with the corresponding amines.

Regiospecific synthesis of functionalised 1,3-diarylisobenzofurans via palladium- and rhodium-catalysed reaction of boronic acids with o-acylbenzaldehydes under thermal or microwave activation

Variously substituted 1,3-diarylisobenzofurans have been regiospecifically prepared via palladium- and rhodium-catalysed reaction of functionalised boronic acids onto o-acylbenzaldehydes. Rhodium catalysis has furthermore been improved using microwave activation. Thus, isobenzofurans containing aryl groups substituted by halogens, unprotected amine, alcohol and even aldehyde groups, have been obtained directly in good to satisfactory yields. Divergent results have been observed when palladium-, rhodium- and MW-activated rhodium-catalysis was applied to the reaction of phenylboronic acid with an iodinated o-acylbenzaldehyde, leading principally to Suzuki coupling product and/or to iodinated isobenzofuran.

ChemInform Abstract: Suzuki—Miyaura Coupling Reaction of Boronic Acids and Ethyl Glyoxylate: Synthetic Access to Mandelate Derivatives.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Novel Petasis Boronic Acid Reactions with Indoles: Synthesis of Indol‐3‐yl‐aryl‐acetic Acids.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Diastereoselective Synthesis of 1,2,3-Trisubstituted Indanes via Rhodium(I)-Catalyzed Tandem Conjugate Additions

1,2,3-Trisubstituted indanes are synthesized with high diastereoselectivity in favor of the all-trans products by the reaction of boronic acids with electron-deficient o-divinylbenzenes under rhodium(I) catalysis.

Suzuki–Miyaura Coupling Reaction of Boronic Acids and Ethyl Glyoxylate: Synthetic Access to Mandelate Derivatives

AbstractThe palladium‐catalyzed coupling reaction of arylboronicacids with ethyl glyoxylate provides a straightforward method for the synthesis of mandelic esters. Pd2(dba)3·CHCl3 in combination with 2‐di‐tert‐butylphosphanylbiphenyl as the catalytic system and Cs2CO3 as the base were used. The reaction tolerates a wide range of functionalized boronicacids. Mandelic esters were isolated in good‐to‐excellent yields with a variety of neutral, slightly electron‐rich, and slightly electron‐poor substituents.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Novel Petasis boronic acid reactions with indoles: synthesis of indol-3-yl-aryl-acetic acids

Indoles can serve as substrates for the Petasis boronic acid-Mannich reaction, providing a practical synthetic route for C–C bond formation in α-(N-substituted indole)carboxylic acids. The scope and limitations of this method have been examined.

Comparison of monomode and multimode microwave equipment in Suzuki–Miyaura reactions— en route to high throughput parallel synthesis under microwave conditions

The microwave heated Suzuki–Miyaura cross-coupling reaction of boronic acids, boronic esters and organotrifluoroborates served as a model reaction in a singlemode equipment. The reaction conditions were optimized with respect to temperature and reaction time and were transferred to multimode equipment which is well suited for multiparallel synthesis in a larger scale. The source of the Pd species chosen included immobilized Pd complexes and Pd particles. In fact the increased time to reach the required reaction time in multimode chambers suitable for 48 parallel reactions has to be taken into account. The nature of the boronic acid has no impact on the efficiency of the catalytic process. However, heterogenized Pd species perform less well in multimode chambers with larger vial volumes, which we ascribe to diffusion phenomena.

Formation of Boronate Ester Polymers with Efficient Intrastrand Charge‐Transfer Transitions by Three‐Component Reactions (Eur. J. Inorg. Chem. 33/2007)

AbstractThe cover picture shows the formation of deeply colored boronate ester polymers by three‐component reactions of boronic acids with 1,2,4,5‐tetrahydroxybenzene and dipyridyl compounds. The strong color of the polymers is due to efficient intrastrand charge transfer excitations from the tetraoxobenzene to the dipyridyl linker. Upon dissolution of the polymers in hot chloroform, most of the B–N connections are broken, which indicates that polymer formation is a reversible process. More details on these reactions are described in the article by K. Severin et al. on page 5177 ff.

Synthesis of 2′-deoxyadenosine nucleosides bearing bipyridine-type ligands and their Ru-complexes in position 8 through cross-coupling reactions

The synthesis of the title 2'-deoxyadenosine derivatives bearing bipyridine, phenanthroline or terpyridine ligands and their corresponding RuII-complexes in position 8 linked via acetylene or phenylene tethers was accomplished through cross-coupling reactions. The Suzuki-Miyaura reactions of boronic acids or the Sonogashira reactions of terminal acetylene derivatives of oligopyridine ligands were performed either on protected 8-bromoadenosines in organic solvents or, more efficiently, directly on unprotected nucleosides in aqueous acetonitrile or DMF. Direct cross-coupling reactions of unprotected nucleosides with RuII-complexes or the oligopyridine-boronic acids or -acetylenes gave the Ru-labelled nucleosides in one step in fair to good yields. This method was also proven to be applicable for direct Ru-labelling of dATP. Terpyridine-containing 2'-deoxyadenosine exerted significant antiviral and cytostatic effects.

A rapid, solvent-free, ligandless and mild method for preparing aromatic ketones from acyl chlorides and arylboronic acids via a Suzuki–Miyaura type of coupling reaction

Aromatic ketones were synthesized via a palladium catalyzed cross-coupling reaction of boronic acids with acyl chlorides in the presence of Na 2CO 3 at room temperature under solvent-free conditions. The ligand-free and mild reaction conditions, highly rapid reaction rate and good to excellent yields are important features of this method.

Palladium‐Catalyzed Reaction of Boronic Acids with Chiral and Racemic α‐Bromo Sulfoxides.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Palladium-Catalyzed Reaction of Boronic Acids with Chiral and Racemic α-Bromo Sulfoxides

Palladium-catalyzed cross-coupling reactions of racemic alpha-bromo sulfoxides with boronic acids are carried out in either aqueous or nonaqueous medium with formation of a new C sp(3)-C sp(2) bond. The arylation of chiral alpha-bromo sulfoxides occurs without racemization. The cross-coupling reaction is general and gives high yields with arylboronic acids substituted with either donor or acceptor groups but gives poor results with heteroarylboronic acids. The best yields are obtained using degassed solvents and CsF instead of aqueous base. The use of aqueous base and the presence of oxygen favor the homocoupling side reaction.

Novel Petasis Boronic Acid Reactions with 1,3,5‐Tri‐oxygenated Benzenes.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Novel Petasis boronic acid reactions with 1,3,5-tri-oxygenated benzenes

1,3,5-tri-Oxygenated benzenes can serve as substrates for the Petasis boronic acid reaction, providing a practical synthetic route for the two CC bond formation of α-(1,3,5-tri-oxygenated phenyl)carboxylic acids. The scope and limitations of this method have been examined.