Nucleophilic C–H Etherification of Heteroarenes Enabled by Base-Catalyzed Halogen Transfer
作者:Thomas R. Puleo、Danielle R. Klaus、Jeffrey S. Bandar
DOI:10.1021/jacs.1c06481
日期:2021.8.18
for the direct C–H etherification of N-heteroarenes. Potassium tert-butoxide catalyzes halogen transfer from 2-halothiophenes to N-heteroarenes to form N-heteroaryl halide intermediates that undergo tandem base-promoted alcohol substitution. Thus, the simple inclusion of inexpensive 2-halothiophenes enables regioselective oxidative coupling of alcohols with 1,3-azoles, pyridines, diazines, and polyazines
A highly efficient and regioselectivedirectC–H trifluoromethylation of pyridine based on an N-methylpyridine quaternary ammonium activation strategy has been developed. A variety of trifluoromethylpyridines can be obtained in good yield and excellent regioselectivity by treating the pyridinium iodide salts with trifluoroacetic acid in the presence of silver carbonate in N,N-dimethylformamide. The
A Modular Synthesis of Functionalized Pyridines through Lewis-Acid-Mediated and Microwave-Assisted Cycloadditions between Azapyrylium Intermediates and Alkynes
conditions to furnish the expected pyridine derivatives 3k and 3l in respectable yields. The 3-bromo-substituted pyridines 11 were further functionalized through palladium-catalyzed couplings such as Suzuki or Sonogashira reactions, which led smoothly to tri- or tetrasubstituted pyridine derivatives such as 19–21 and 23. Reductive debromination of 11e afforded the pyridine 17 in excellent yield, whereas
Towards environmentally friendlier Suzuki–Miyaura reactions with precursors of Pd-NHC (NHC = N-heterocyclic carbene) complexes
作者:Caroline M. Zinser、Katie G. Warren、Rebecca E. Meadows、Fady Nahra、Abdullah M. Al-Majid、Assem Barakat、Mohammad S. Islam、Steven P. Nolan、Catherine S. J. Cazin
DOI:10.1039/c8gc00860d
日期:——
preparation of [NHC·H][Pd(η3-R-allyl)Cl2] complexes is disclosed and represents a facile, atom-economical, environmentally friendly and rapid synthesis. These palladates are immediate synthetic precursors to the well-known [Pd(NHC)(η3-R-allyl)Cl] complexes. Their activation leading to catalytically relevant species has been studied in the Suzuki–Miyaura reaction. The need for an activation step prior
A simple synthetic entryway into palladium cross-coupling catalysis
作者:Caroline M. Zinser、Fady Nahra、Marcel Brill、Rebecca E. Meadows、David B. Cordes、Alexandra M. Z. Slawin、Steven P. Nolan、Catherine S. J. Cazin
DOI:10.1039/c7cc02487h
日期:——
The simple synthesis of a family of palladates containing an imidazolium counterion is presented. These “ate” complexes can be easily converted into well-defined palladium–N-heterocyclic carbene (NHC) complexes. The synthetic protocols leading to the “ate” and to the Pd–NHC neutral complexes have been exemplified with various NHC ligands. The palladates prove efficient pre-catalysts enabling Suzuki–Miyaura