Synthetic applications of N–N linked heterocycles. Part 12. The preparation of 4-alkylthio- and 4-arylthio-pyridines by regiospecific attack of thioalkoxide lons on N-(4-oxopyridin-1-yl)pyridinium salts
作者:Michael P. Sammes、Christopher W. F. Leung、Chi Keung Mak、Alan R. Katritzky
DOI:10.1039/p19810001585
日期:——
Thiolate ions add regiospecifically to N-(4-oxopyridin-1-yl)pyridinium salts (2)–(7) to give in good to excellent yields only the 1,4-dihydropyridine adducts (8)–(13), regardless of whether or not the pyridone moiety carries substituents for sterically shielding the 2- and 6-positions of the pyridinium ring. The addition is believed to be thermodynamically controlled. Decomposition of the dihydro-adducts
硫醇离子对N-(4-氧代吡啶-1-基)吡啶鎓盐(2)-(7)呈区域特异性添加,仅产生1,4-二氢吡啶加合物(8)-(13)即可获得优异的优良收率吡啶酮部分是否带有取代基以立体屏蔽吡啶鎓环的2位和6位。据信该添加是热力学控制的。在自由基条件下或通过热解分解二氢加合物,尽管2-甲基加合物(9)反应失败,但吡啶4-基硫醚(14)和(16)的收率很高。还描述了6-甲基-4-氧杂吡喃-2-羧酸的改进的合成。