Synthesis of biindolyls via palladium-catalyzed reactions

An unprecedented synthesis of a range of high value homo- and heterobiindolyls is presented. The one-pot Miyaura borylation and subsequent Suzuki-Miyaura coupling sequence allows for the construction of the highly sterically congested C-C bond between two bromoindoles in modest to good overall yields.     

Synthesis of novel bicyclic pyridazine nucleosides

The synthesis of some [6:6]- or [6:5]-fused bicyclic pyridazin-6-one nucleosides, starting from 4,5-dichloro-3-nitro(or amino) and 3-hydrazinopyridazin-6-one nucleosides is described.     

Synthesis of bicyclic quinones via 1,4-diacetoxyanthracene

1,4-Diacetoxyanthracene is introduced as a convenient intermediate for the syntheses of bicyclic quinones and diquinones.     

Synthesis of novel steroid analogues containing nitrile and disulfide moieties via palladium-catalyzed cross-coupling reactions

Grundmann's ketone (3) was used as a common building block for introduction of the C+D ring motif of steroids to prepare series of novel secosteroids containing nitrile or disulfide functionalities. Key steps in synthesis of these novel steroid analogues are palladium-catalyzed cross-coupling reactions. All target compounds were characterized by comprehensive analysis; in particular the stereochemical assignments of dinitriles 12a and 12b could be carried out in detail by NMR experiments. The pharmacological potential of all compounds was initially verified by a cytotoxicity test.     

Synthesis of thiophene derivatives via palladium-catalyzed coupling reactions

Thiophene derivatives with multiple substitutions are prepared from vinylidene bromide, which is synthesized by the reaction of thiophene-2-carboxaldehyde with carbon tetrabromide in the presence of PPh₃, as a core molecule through several coupling reactions such as Suzuki-Miyaura coupling and palladium-catalyzed CH arylation. The reactions with a wide variety of organic halides lead to a series of substituted thiophene derivatives in moderate to good yields.     

Synthesis of the kappa-agonist CJ-15,161 via a palladium-catalyzed cross-coupling reaction

Syntheses of CJ-15,161 (1) involving intermolecular N-arylation of an appropriately functionalized diamine, obtained from the precursor alpha-amino acids or, more conveniently, from the corresponding 1,2-amino alcohols via 1,2,3-oxathiazolidine-2,2-dioxide 22, are reported.     

Synthesis of 9-alkylidene-9H-fluorenes by a novel palladium-catalyzed rearrangement

In the presence of a palladium catalyst and NaOAc, aryl iodides react with 1-aryl-1-alkynes to afford 9-alkylidene-9H-fluorenes in good yields. This process appears to involve (1) oxidative addition of the aryl iodide to Pd(0), (2) alkyne insertion, (3) rearrangement of the resulting vinylic palladium intermediate to an arylpalladium species, and (4) aryl-aryl coupling with simultaneous regeneration of the Pd(0) catalyst.     

Synthesis of isoindolinones via palladium-catalyzed C-H activation of N-methoxybenzamides

The synthesis of isoindolinones from N-methoxybenzamides and alkenes has been achieved by Pd-catalyzed ortho sp(2) C-H activation and intramolecular oxidative amidation, which involve the cleavage of four bonds and formation of two bonds.     

Synthesis of amides via palladium-catalyzed amidation of aryl halides

A new and efficient method for the synthesis of amides via palladium-catalyzed C-C coupling of aryl halides with isocyanides is reported, by which a series of amides were formed from readily available starting materials under mild conditions. This transformation could extend its use to the synthesis of natural products and significant pharmaceuticals.     

Synthesis of dihydrofuroflavonoids via palladium-catalyzed annulation of 1,3-dienes

The palladium-catalyzed annulation of 1,3-dienes by o-iodoacetoxyflavonoids provides an efficient approach to biologically interesting dihydrofuroflavonoids. This reaction is very general, regioselective, and a wide variety of terminal, cyclic, and internal 1,3-dienes can be utilized.     

Synthesis of sterically congested bicyclic tetrahydrofurans via Pd-catalyzed cyclization

Prins-type cyclization followed by palladium-catalyzed cyclization provided sterically congested bi- or tricyclic tetrahydrofurans, which are very stereoselective as well. cis-2,5-Disubstituted tetrahydrofurans obtained from Prins-type cyclization have an allenyl group and a functional group such as alcohol, carboxylic acid, and aryl halide. The tetrahydrofurans bearing an allene group underwent palladium-catalyzed cyclization to give sterically congested bi- or tricyclic tetrahydrofurans.     

A novel three-step synthesis of Celecoxib via palladium-catalyzed direct arylation

A novel three linear step synthesis of Celecoxib was achieved in 33% overall yield via a key regioselective direct C-H arylation reaction between a 1,3-disubstituted pyrazole and an aryl bromide.     

Synthesis of polysubstituted 5-azaindoles via palladium-catalyzed heteroannulation of diarylalkynes

A general and efficient procedure for the synthesis of functionalized 5-azaindoles through the catalyzed heteroannulation of 4-acetamido-3-iodopyridines and diarylalkynes is described. The reaction allows the preparation of a variety of substituted 2,3-diaryl-5-azaindoles in good to excellent yields.     

Synthesis of novel tryptamine and β-carboline derivatives via palladium-catalyzed reaction of bromotryptamine with organic boronic acids

New tryptamine 5, 7 and β-carboline derivatives 3 were preparated by palladium-catalyzed coupling reaction of 5-bromotryptamine 1 with aryl boronic acids. Dedicated to Professor András Lipták on his 70^th birthday.     

Synthesis of fluoren-9-ones via palladium-catalyzed cyclocarbonylation of o-halobiaryls

The synthesis of various substituted fluoren-9-ones has been accomplished by a novel palladium-catalyzed cyclocarbonylation of o-halobiaryls. The cyclocarbonylation of 4'-substituted-2-iodobiphenyls produces very high yields of 2-substituted fluoren-9-ones bearing either electron-donating or electron-withdrawing substituents. 3'-Substituted 2-iodobiphenyls afford in excellent yields with good regioselectivity 3-substituted fluoren-9-ones. This chemistry has been successfully extended to polycyclic and heterocyclic fluorenones.     

Synthesis of 2-anilinotropones via palladium-catalyzed amination of 2-triflatotropone

[reaction: see text] A series of 2-anilinotropones were synthesized via the palladium-catalyzed cross coupling of 2-triflatotropone and a wide variety of anilines, sterically hindered as well as electron-poor ones.     

Synthesis of novel tetrahydroindeno[1,2-b]pyrrolidines via Ugi multicomponent and palladium-catalyzed aerobic oxidative cyclization

Novel tetrahydroindeno[1,2-b]pyrrolidines were conveniently prepared in moderate to good yields via a sequential Ugi multicomponent reaction or Staudinger/aza-Wittig/Ugi combination, followed by the palladium-catalyzed aerobic oxidative cyclization of the resulting Ugi adducts.     

Synthesis of 2-substituted indoles via a palladium-catalyzed domino Heck reaction and dealkylation

A palladium-catalyzed domino Heck reaction and dealkylation for the preparation of 2-substituted indoles is described. This novel transformation is based on an intramolecular Heck reaction followed by dealkylation.     

Synthesis of a dicyclobutylideneethane derivative via sequential palladium-catalyzed Miyaura borylation and Suzuki coupling

An efficient synthesis of a dicyclobutylideneethane derivative was achieved using a palladium-catalyzed reaction of a substituted (bromomethylene)cyclobutane with bis(pinacolato)diboron. The reaction mechanism was investigated in detail. The Suzuki cross-coupling reaction of a (bromomethylene)cyclobutane with arylboronic acid was also achieved.