Palladium-catalyzed Suzuki Cross-coupling Reaction Research Articles

Ultrasound promoted Suzuki cross-coupling reactions in ionic liquid at ambient conditions.

Palladium catalyzed Suzuki cross-coupling reactions of halobenzenes including chlorobenzenes with phenylboronic acid have been achieved at ambient temperature (30 degrees C) in the absence of a phosphine ligand using the ionic liquid 1,3-di-n-butylimidazolium tetrafluoroborate [bbim][BF4] with methanol as co-solvent under ultrasonic irradiation.

Sterically Encumbered Porphyrins by Suzuki Reactions of a 5,15-Bis(4,6-dichloropyrimidin-5-yl) Derivative

The high yielding synthesis of novel four picket fence porphyrins via palladium catalyzed Suzuki cross-coupling reactions of 5,15-bis(pyrimidinyl)porphyrin 1 and commercially available arylboronic acids is described.

Biaryl synthesis via Suzuki coupling promoted by catalytic amounts of quaternary ammonium salts

Palladium-catalyzed Suzuki cross-coupling reaction (between phenylboronic acid and 4-bromobenzonitrile) in presence of catalytic quaternary ammonium salts is described. With Aliquat 336 (tricaprilylmethylammonium chloride), the rates of the reaction were increased in DME and toluene allowing to work with lower stirring and at lower temperatures in some cases.

Total Synthesis of the Marine Alkaloids (−)-Lepadins A, B, and C Based on Stereocontrolled Intramolecular Acylnitroso-Diels−Alder Reaction

The first syntheses of (-)-lepadins A and C, as well as a new synthesis of (-)-lepadin B, have been achieved from commercially available (S)-malic acid. The methodology is based on an intramolecular hetero-Diels--Alder reaction of the acylnitroso compound, affording the bicyclic oxazino lactam with trans selectivity, which was converted to the cis-decahydroquinoline via asymmetric enolate hydroxylation followed by intramolecular aldol cyclization. The total syntheses proceed by employing cis-decahydroquinoline bearing the (E)-iodoalkenyl group as the common key intermediate, which underwent a convergent coupling with the (E)-hexenyl unit via a palladium-catalyzed Suzuki cross-coupling reaction for the elaboration of the octadienyl side chain at the C5 position.

Synthesis of 6-aryl-2,4-diamino-pyrimidines and triazines using palladium catalysed Suzuki cross-coupling reactions

The high yielding synthesis of 6-aryl-2,4-diaminopyrimidines and triazines via palladium catalysed Suzuki cross-coupling reactions of commercially available 6-chloro-2,4-diaminopyrimidine 1 or 6-chloro-2,4-diaminotriazine 8 and aryl boronic acids are described.

Structural studies on bioactive compounds. Part 29: Palladium catalysed arylations and alkynylations of sterically hindered immunomodulatory 2-amino-5-halo-4,6-(disubstituted)pyrimidines

The immunological agent bropirimine 5 is a tetra-substituted pyrimidine with anticancer and interferon-inducing properties. Synthetic routes to novel 5-aryl analogues of bropirimine have been developed and their potential molecular recognition properties analysed by molecular modelling methods. Sterically challenged 2-amino-5-halo-6-phenylpyrimidin-4-ones (halo=Br or I) are poor substrates for palladium catalysed Suzuki cross-coupling reactions with benzeneboronic acid because the basic conditions of the reaction converts the amphoteric pyrimidinones to their unreactive enolic forms. Palladium-mediated reductive dehalogenation of the pyrimidinone substrates effectively competes with cross-coupling. 2-Amino-5-halo-4-methoxy-6-phenylpyrimidines can be converted to a range of 5-aryl derivatives with the 5-iodopyrimidines being the most efficient substrates. Hydrolysis of the 2-amino-5-aryl-4-methoxy-6-phenylpyrimidines affords the required pyrimidin-4-ones in high yields. Semi-empirical quantum mechanical calculations show how the nature of the 5-substituent influences the equilibrium between the 1H- and 3H-tautomeric forms, and the rotational freedom about the bond connecting the 6-phenyl group and the pyrimidine ring. Both of these factors may influence the biological properties of these compounds.

Convergent synthesis of an HIJK ring model of ciguatoxin via Suzuki cross-coupling reaction

Convergent synthesis of HIJK ring model compound 1 of ciguatoxin is described. The present synthesis relied on a palladium-catalyzed Suzuki cross-coupling reaction between eight-membered ketene acetal phosphate 2 and seven-membered alkylborane 6.

Palladium catalysed Suzuki cross-coupling reactions in ambient temperature ionic liquids

Palladium catalysed Suzuki cross-coupling reactions have been conducted in the ambient temperature ionic liquid,1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]), exhibiting unprecedented reactivities in addition to easy product isolation and catalyst recycling.

Palladium-bisimidazol-2-ylidene complexes as catalysts for general and efficient Suzuki cross-coupling reactions of aryl chlorides with arylboronic acids

A series of bisimidazolium salts 1– 6 were synthesized and evaluated as precursors to bisimidazol-2-ylidene ligands in palladium-catalyzed Suzuki cross-coupling reactions with aryl chlorides and arylboronic acids. The bisimidazolium salt 6 was found to be superior over imidazolium and other bisimidazolium salts affording high yields of biaryl products employing a wide variety of substrates.

Total Synthesis and Structural Refinement of the Cyclic Tripyrrole Pigment Nonylprodigiosin.

The first total synthesis of the cyclic prodigiosin derivative 4 is described, which constitutes a potential lead compound for the development of immunosuppressive agents. The key steps of this approach comprise a palladium-catalyzed Suzuki cross coupling reaction of the rather unstable pyrrole boronic acid derivative 17 with the electron rich pyrrolyl triflate 15 followed by a ring-closing metathesis reaction (RCM) of the resulting diene to form the macrocyclic ring of the target molecule. This transformation is best achieved by using the ruthenium indenylidene complex 21 as precatalyst. X-ray data of product 18.HCl thus formed suggest that the tautomeric form B properly describes the electron distribution within the heteroaromatic segment of this alkaloid, in which the central ring constitutes the azafulvene unit of the pyrrolylpyrromethene chromophore.

Two syntheses of the 16- and 17-membered DEF ring systems of chloropeptin and complestatin.

[formula: see text] Two syntheses of a model system of the DEF ring system of complestatin and chloropeptin are described. The key step in both of these syntheses involves the formation of the biaryl linkage using a palladium-catalyzed Suzuki cross-coupling reaction and a catalytic enantioselective ene reaction to form the 6-bromo-D-tryptophan. Additionally, ring contraction of the 17-membered DEF ring system of complestatin generates the 16-membered DEF ring system of chloropeptin in a biomimetic fashion.

Palladium catalyzed cross-coupling reaction of organoboronic acids with β-(perfluoroalkyl)ethyl iodides

Palladium catalyzed Suzuki cross-coupling reaction of β-(perfluoroalkyl)ethyl iodides with organoboronic acids proceeds smoothly to provide the corresponding cross-coupling products in the presence of the weak base NaHCO 3 in aqueous ethylene glycol dimethyl ether (DME) in moderate to good yields.

Preparation of new functionalized hydrocarbon linkers via Suzuki cross coupling reaction

Treatment of a vinyl resin with 9-BBN affords a polymer bound alkylborane that undergoes palladium-catalyzed Suzuki cross coupling reactions with a variety of aromatic, vinylic and aliphatic halides. The mild reaction conditions are compatible with several functional groups and allow carboncarbon bond formation at non-activated positions.

New strategy for convergent synthesis of trans-fused polyether frameworks based on palladium-catalyzed suzuki cross-coupling reaction

A new strategy for convergent synthesis of trans-fused polyethers based on palladium(0)-catalyzed Suzuki cross-coupling reaction of alkylboranes with cyclic enol triflates has been developed. The present method allows to construct polyether frameworks rapidly and efficiently.

Total Synthesis of Caloporoside

The first total synthesis of the fungal metabolite caloporoside 1, a strong and selective inhibitor of phospholipase C, is described. Both sugar units of its complex disaccharidic segment were obtained from 3,4,6-tri-O-benzyl-d-glucopyranose 14 as a common building block, with d-gluco → d-manno inversions as the key strategic elements. This particular substitution reaction occurred readily on the acyclic segment (27 → 28), whereas ultrasonication was required to override adverse stereoelectronic effects upon formation of β-d-mannopyranoside unit 34. The (16R)-hydroxyheptadecylsalicylic acid part of 1 was efficiently prepared by a palladium-catalyzed Suzuki cross coupling reaction of aryltriflate 7 with the 9-alkyl-9-BBN derivative formed from alkene 6 and 9-H-9-BBN.

Shortcut Syntheses of Naturally Occurring 5-Alkylresorcinols with DNA-Cleaving Properties.

Resorcinols such as 1-5 bearing long alkyl- or alkenyl substituents at the C-5 position, including bola-formed bis-resorcinol derivatives, have recently been isolated from natural sources and were shown to exhibit exceptional DNA-cleaving properties under oxidative conditions. Previous synthetic approaches to such compounds seem inappropriately lengthy with regard to their structural simplicity. Disclosed is a very flexible synthesis which assembles these targets from triflate 7 and well accessible alkenes, dienes, enynes, or dienynes, respectively, by means of a boron-mediated reaction manifold. As a typical example, hexadeca-1,15-dien-8-yne 11 is hydroborated with 9-H-9-BBN at all possible sites, the alkenyl borane entity of the resulting tris-borane 12 is selectively cleaved off to afford the desired (Z)-alkene group in a stereoselective manner, the remaining two terminal alkylboranes are treated with NaOMe, and the bis-borate complex 13 thus formed is finally used as the nucleophile for a palladium-catalyzed Suzuki cross-coupling reaction with triflate 7. This sequence is carried out in one pot and provides product 14 in 62% overall yield. Demethylation of 14 (and analogues) can be conveniently achieved by means of 9-iodo-9-BBN to afford the natural product 5. The efficiency and flexibility of this unprecedented approach which combines different features of classical and modern boron chemistry is further demonstrated by the synthesis of anacardic and ginkgolic acid derivatives.

Synthesis of beta-aryl substituted porphyrins by palladium catalyzed Suzuki cross-coupling reactions

β-Bromoporphyrins undergo Suzuki cross coupling reactions with aryl boronic acids to give β-arylporpyrins in high yields.