ABSTRACT
An efficient and inexpensive LiI-promoted O- to N-alkyl migration of 2-benzyloxy-, 2-allyloxy-, and 2-propargyloxypyridines and heterocycles is reported. The reaction produces the corresponding N-alkyl 2-pyridones and analogues under green, solvent-free conditions in good to excellent yields (30 examples, 20-97% yield). This method has been shown to be intermolecular and requires heat and lithium cation to occur.
Subject(s)
Iodides/chemistry , Lithium/chemistry , Pyridones/chemical synthesis , Alkylation , Molecular Structure , Pyridones/chemistryABSTRACT
The mechanisms for Ni(dppe)Cl(2)-catalyzed chain-growth polymerization of 4-bromo-2,5-bis(hexyloxy)phenylmagnesium chloride and 5-bromo-4-hexylthiophen-2-ylmagnesium chloride were investigated. Rate studies utilizing IR spectroscopy and gas chromatography revealed that both polymerizations exhibit a first-order dependence on the catalyst concentration but a zeroth-order dependence on the monomer concentration. (31)P NMR spectroscopic studies of the reactive organometallic intermediates suggest that the resting states are unsymmetrical Ni(II)-biaryl and Ni(II)-bithiophene complexes. In combination, the data implicate reductive elimination as the rate-determining step for both monomers. Additionally, LiCl was found to have no effect on the rate-determining step or molecular weight distribution in the arene polymerization.
Subject(s)
Coordination Complexes/chemistry , Coordination Complexes/chemical synthesis , Organometallic Compounds/chemical synthesis , Phenyl Ethers/chemical synthesis , Thiophenes/chemical synthesis , Catalysis , Molecular Structure , Organometallic Compounds/chemistry , Phenyl Ethers/chemistry , Stereoisomerism , Thiophenes/chemistryABSTRACT
A new LiI-promoted O- to N-alkyl migration has been developed for the conversion of O-alkylated 2-hydroxy pyridines, quinolines, and pyrimidines to the corresponding N-alkylated heterocycles in good to excellent yields (57-99%). This method serves as an efficient means for the preparation of N-benzyl pyridones, quinolones, and pyrimidones.
Subject(s)
Benzyl Compounds/chemical synthesis , Pyridones/chemical synthesis , Alcohols/chemistry , Alkylation , Iodides/chemistry , Lithium Compounds/chemistry , Pyridines/chemical synthesis , Pyridines/chemistry , Pyrimidines/chemistry , Pyrimidinones/chemical synthesis , Quinolines/chemistry , Quinolones/chemical synthesisABSTRACT
A highly efficient and regioselective Pd-catalyzed method for the oxidative coupling of arylpyridine derivatives is reported. Remarkably, the reactions proceed at room temperature and are compatible with diverse functionalities, including aryl halides and thiophenes. Mechanistic studies suggest that these transformations proceed via a previously unprecedented mechanism involving two different pyridine-directed C-H activation reactions-one at a PdII center and one at PdIV.