Ultrasound-promoted intramolecular direct arylation in a capillary flow microreactor

An intramolecular direct arylation of various aryl bromides was performed using ultrasonic irradiation and a continuous flow capillary microreactor. The present procedure provided a higher functional group tolerance, ligand-free, milder reaction conditions and a shorter reaction time for the direct arylation compared with the conventional methods. The ultrasonic irritation not only greatly promoted the conversion and selectivity of the direct arylation, but also solved the clogging problem of the microreactor for solid-forming reaction and made the reaction run smoothly.     

Palladium-catalyzed syntheses of tetrahydrocarbazolones as advanced intermediates to carbazole alkaloids

Two sequential palladium-catalyzed reactions, an intermolecular Stille cross-coupling followed by a recently developed palladium-catalyzed reductive N-heteroannulation, have been employed as the key synthetic steps toward six tetrahydrocarbazolones. The products are advanced intermediates toward a number of naturally occurring carbazole alkaloids.     

钯催化C-N偶联构筑吲哚衍生物反应研究

以炔基苯胺衍生物为底物,通过钯催化C-N偶联合成一类系列吲哚衍生物。优化实验表明,以2%醋酸钯为催化剂,4%三苯基磷为配体,在有机碱的DMF溶液中加热至130℃为优化实验条件。产物结构经IR、1H NMR、13C NMR、HRMS分析确证,其中化合物2e经X射线单晶衍射分析确证。     

Mild conditions for Pd-catalyzed conversion of aryl bromides to primary anilines using benzophenone imine

Mild (30 °C) and efficient (53-91%) conversion of aryl bromides to primary anilines using a Pd-catalyzed amination strategy is described. A detailed account of the ligand optimization, base and solvent selection, and general substrate scope of this methodology is described herein.     

Total Syntheses of the Alkaloids Ipalbidinium and Clathryimine B

Summary.  The indolizidinium alkaloid ipalbidinium and the quinolizidinium alkaloid clathryimine B were prepared starting from brominated 2-aminopyridines using two Pd-catalyzed cross-coupling reactions and a Sandmeyer-type diazotation/iodination protocol as the key steps. Corresponding author. E-mail: Franz.Bracher@cup.uni-muenchen.de Received August 2, 2002; accepted August 9, 2002     

Microwave promoted palladium-catalyzed Suzuki-Miyaura cross-coupling reactions of 6-chloropurines with sodium tetraarylborate in water

An efficient method for the synthesis of 6-arylpurines (nucleosides) was developed via Suzuki-Miyaura cross-coupling reactions of 6-chloropurines (nucleosides) and sodium tetraarylborate in neat water (ethanol). The process gave good to high isolated yields within a short reaction time under microwave irradiated conditions.     

Unexpected formation of (Z)-3-(halomethylene)isoindolinones from gem-dihalovinylbenzonitriles: efficient synthesis of enyne-containing isoindolinones

An efficient one-pot procedure for the regioselective synthesis of (Z)-3-(halomethylene)-isoindolin-1-ones was developed from easily accessible 2-(2,2-dihalovinyl)benzonitriles. From this key intermediate, a variety of isoindolinones containing an enyne moiety were synthesized in good to excellent yields via palladium-catalyzed Sonogashira reaction. The generated enyne-containing isoindolinones could be further manipulated by iodide induced cyclization reaction to afford a versatile synthetic intermediate 5H-pyrrolo[2,1-a]isoindolol-5-one in high yield and could be further elaborated.     

Synthesis of substituted benzimidazo[2,1-a]isoquinolines and its condensed analogues using Pd(0)-catalyzed cyclization/C-H activation

An efficient route for the synthesis of benzimidazo[2,1-a]isoquinolines and its condensed analogues has been developed via the palladium-catalyzed cyclization/C-H activation of N-allyl and N-methallyl derivatives of benzimidazoles.     

Palladium-catalyzed epimerization of γ-alkenyl-γ-butyrolactone derivatives

γ-Alkenyl-α,β,γ-trisubstituted-γ-butyrolactones (12-16) and γ-alkenyl-furofurandione derivatives (21-Z-24-Z; 21-E-24-E; 25-Z-28-Z; and 25-E-28-E) were successfully epimerized in high yield by a palladium catalyst.     

Direct C-H bond arylation of 2-hydroxybenzaldehydes with arylboronic acids via ligand-free palladium catalysis

A mild and efficient ligand-free palladium-catalyzed direct C-H bond arylation reaction was developed to afford 2-hydroxybenzophenones in good to excellent yields from easily available 2-hydroxybenzaldehydes and arylboronic acids. The given reaction provided one of the easiest pathways for accessing 2-hydroxybenzophenones, and a variety of functional groups could be tolerated in this process.