Water works: an efficient palladium-catalyzed cross-coupling reaction between boronic acids and bromoacetate with aminophosphine ligand

Water greatly restrained the formation of self-coupling of boronic acids in a palladium-catalyzed cross-coupling reaction between boronic acids and ethyl bromoacetate with an aminophosphine ligand; good to excellent yields of cross-coupling product were obtained.     

SYNTHESIS AND PHOTOPHYSICAL PROPERTIES OF POLY(ARYL IMINO) CONTAINING ACRIDINE UNITS(PAIA)

1,4-Bis-(4-bromobenzoyl)benzene and proflavine,3,6-diaminoacridine free base were synthesized first.Using 1,4- bis-(4-bromobenzoyl)benzene and proflavine,3,6-diaminoacridine free base as the monomers,poly(aryl imino) containing acridine units(PAIA) was synthesized via palladium-catalyzed amination.The structure of PAIA was characterized by means of FTIR,~1H-NMR spectroscopy and elemental analysis,the results show an agreement with the proposed structure.The UV absorption and photoluminescence spectra wer...     

Synthesis of 2,6-dimethyl-9-aryl-9-phosphabicyclo[3.3.1]nonanes: their application to asymmetric synthesis of chiral tetrahydroquinolines and relatives

Synthesis of 2,6-dimethyl-9-aryl-9-phosphabicyclo[3.3.1]nonanes from 1,5-cyclooctadiene and their application to asymmetric cyclization leading to chiral tetrahydroquinolines and relatives through palladium-catalyzed allylic alkylation are described.     

Selective palladium-catalyzed amination of β-chloroacroleins by substituted anilines

β-Chloroacroleins can undergo a selective amination on their chloro position under palladium catalysis; in those conditions, no imine formation was observed. Their coupling with anilines carrying electron-donating or electron-withdrawing substituents proceeds in moderate to good yields and steric hindrance does not seem to be a limitation as o-substituted anilines react readily.     

Palladium-catalyzed homocoupling of arenediazonium salts: an operationally simple synthesis of symmetrical biaryls

A simple procedure for the intermolecular homocoupling of arenediazonium salts in air using a catalytic amount of palladium acetate is described. The optimum conditions were found to be 15 mol % palladium acetate in refluxing methanol, with no additional terminal reducing agent required. These optimized conditions were used to prepare biaryls from several arenediazonium tetrafluoroborate salts, and most examples proceeded in moderate to high yields.     

Synthesis of the first pentaethynylferrocene derivatives

Starting from a bisprotected ferrocene-1,2,3-triscarbaldehyde, Ohira-alkynylation and Pd-catalyzed protection of the free alkyne with 4-iodotoluene leads to a ferrocene in which one Cp-ring is 1,2,3-substituted by two acetal rings (1,2-position) and an internal alkyne. Metalation of the ferrocene nucleus with sec-BuLi, workup with DMF and reduction with LiAlH₄ leads to a 1,2,3,4-tetrasubstituted ferrocene carrying a hydroxymethyl group. The acetal groups are removed by para-toluenesulfonic acid and the aldehyde groups are converted into arylalkynes. A second metalation followed by workup with DMF furnishes a 1,2,3,4,5-pentasubstituted ferrocenecarbaldehyde. The aldehyde is transformed into an alkyne by the Ohira method and converted to an internal alkyne by Pd-catalyzed reaction with 4-iodotoluene. The sequence gives a 1,2,3,4,5-pentasubstituted ferrocene derivative with four alkyne groups and one hydroxymethyl group. Airless Marko oxidation of the alcohol is followed by another Ohira alkynylation. Pd-catalyzed arylation finishes the reaction sequence to give the symmetrical 1,2,3,4,5-pentakis(4′-tolylethynyl)ferrocene, the first pentaethynylferrocene derivative. A second, similar route was explored that furnished 1,2,3,4,5-pentakis(4′-butylphenylethynyl)ferrocene and its butadiyne-bridged dimer.     

Synthesis of 4-Oxo-1,2,3,4-tetrahydro-β-carbolines via Palladium-Catalyzed Intramolecular Cyclization of Bromoenaminones

The synthesis of 4-oxo-1,2,3,4-tetrahydro-β-carbolines from bromoenaminones derived from 1-substituted piperidine-3,5-dione is described. The reaction proceeds by the intramolecular cyclization of bromoenaminones involving arylpalladium complexes.     

Polycondensation of haloarylketones catalyzed by palladium compounds bearing N-heterocyclic carbene (NHC) ligands

Palladium-catalyzed α-arylation of ketones, which can efficiently give coupling products by using appropriate ligands and bases, could be applied to a polycondensation reaction. Stable N-heterocyclic carbenes (NHC) were used as favorable ligands coordinating the Pd catalysts, which were generated in situ from commercially available palladium compounds such as Pd(OAc)₂ and Pd₂(dba)₃ as suitable catalyst precursors in this polymerization. Using small amounts of binary catalysts, poly(aryl alkyl ketone)s were afforded in high yields from haloarylketones in the presence of a base. A primarily prepared palladium catalyst having an NHC ligand, [Pd(OAc)₂(NHC)], also efficiently catalyzed the polycondensation, whereas a palladium compound bearing two carbene ligands, [PdX₂(NHC)₂], did not.     

Stereospecific preparation of symmetrical (1Z, 3Z)- and (1E, 3E)-2,3-difluoro-1,4-disubstituted-buta-1,3-dienes from 1-bromo-1-fluoroalkenes

A straightforward method to prepare symmetrical (1Z, 3Z)- and (1E, 3E)-2,3-difluoro-1,4-disubstituted-buta-1,3-dienes is described. High E/Z ratio 1-bromo-1-fluoroalkenes, prepared by isomerization from the E/Z ≈ 1:1 isomeric mixtures, reacted with Bu₃SnSnBu₃ and Pd(PPh₃)₄ to afford (1Z, 3Z)-2,3-difluoro-1,4-disubstituted-buta-1,3-dienes in good yield. (Z)-1-Bromo-1-fluoroalkenes, which were prepared by kinetic reduction from 1-bromo-1-fluoroalkenes (E/Z ≈ 1:1), can undergo similar reaction with Bu₃SnSnBu₃ and Pd(PPh₃)₄/CuI to prepare (1E, 3E)-2,3-difluoro-1,4-disubstituted-buta-1,3-dienes.     

Palladium-catalyzed tandem carbonylation and intramolecular diels-alder reaction of 4-alken-2-ynyl carbonates: a new synthetic method for polycyclic compounds

A new synthetic method for polycyclic compounds via the palladium-catalyzed tandem carbonylation and intramolecular Diels-Alder reaction is described.