Microwave Assisted Rapid Preparation of N-Alkyl-2-pyridones under Neutral Conditions by Hilbert-Johnson Reaction
摘要:
The reactions of 2-methoxypyridine with haloalkanes without solvent and catalyst under microwave irradiation (100-200 degrees C, 5 min) yielded the corresponding N-alkyl-2(1H)-pyridones in good to moderate yields. However, the reactions were sensitive to length of haloalkanes. In contrast, the reactions of 2-alkoxypyridines with corresponding iodoalkanes under microwave irradiation (150 degrees C) proceeded rapidly without catalyst and solvent, and were complete within 5 min to afford N-alkyl-2(1H)-pyridones in good to excellent yields.
Excellent correlation between substituent constants and pyridinium N-methyl chemical shifts
作者:Sha Huang、Jesse C.S. Wong、Adam K.C. Leung、Yee Man Chan、Lili Wong、Myrien R. Fernendez、Amanda K. Miller、Weiming Wu
DOI:10.1016/j.tetlet.2009.06.081
日期:2009.9
Substituents on the pyridinium ring of N-methylpyridinium derivatives, especially those on the 2- or 4-position, have a large effect on the 1H and 13C NMR chemical shifts of the N-methyl group. Reasonable correlations between the chemical shift changes and the resonance substituentconstants are observed. The dual substituent parameter approach provides an excellent correlation when a combination of