Ammonium iodide-promoted cyclization of ketones with DMSO and ammonium acetate for synthesis of substituted pyridines
作者:Xiaojun Pan、Qiao Liu、Liming Chang、Gaoqing Yuan
DOI:10.1039/c5ra07584j
日期:——
A simple and efficient method has been developed for the synthesis of symmetrical and unsymmetrical pyridines via NH4I-promoted cyclization of ketones with DMSO and NH4OAc. It was found that methyl ketones always gave selective formation of the unsymmetrical pyridine, while non-methyl ketones gave unpredictable results (symmetrical or non-symmetrical product only, or a mixture of the two). In addition
Fe-catalyzed N–O bond cleavage of ketoxime carboxylates in the presence of tertiary anilines. The methylene carbon on N,N-dialkylanilines functioned as a source of one-carbon synthon in the reaction. The reaction used readily available starting materials, tolerated various functional groups, and afforded 2,4-disubstituted and 2,4,6-trisubstituted pyridines in good to high yields under mild conditions.
A simple and selective one-pot synthesis of 2,4- and 2,6-diarylpyridines through the cyclocondensation reaction of aromatic ketones with ammonium acetate has been developed. The procedure is metal-free, convenient, and efficient, and the substrates are readily available.