Functionalization of the pyridazin-3(2H)-one ring via palladium-catalysed aminocarbonylation
作者:Attila Takács、Andrea Czompa、Gábor Krajsovszky、Péter Mátyus、László Kollár
DOI:10.1016/j.tet.2012.07.030
日期:2012.9
5-Iodo- and 4,5-dibromo-2-methylpyridazin-3(2H)-ones were aminocarbonylated in the presence of various amines including amino acid methyl esters in a palladium-catalysed reaction. The iodo derivative afforded the corresponding amides with complete conversion and high isolated yields. The dibromo derivative has shown unexpectedly high reactivity in this reaction, resulting in 4,5-dicarboxamides using primary amines as N-nucleophiles. Monoaminocarbonylation has not been observed, i.e., neither 4-bromo-5-carboxamide nor 4-carboxamido-5-bromo derivatives have been formed. However, the use of secondary amines such as piperidine and morpholine resulted in the formations of mixtures of amino-substituted bromopyridazinones. That is, no carbon monoxide insertion took place in these cases. Some mechanistic details of the formation of aminocarbonylation and amination products are also discussed. (C) 2012 Elsevier Ltd. All rights reserved.