Condensation of cyanothioacetamide (4) with ethyl alpha-(ethoxymethylene)acetoacetate (5b), ethyl 4-ethoxy-2-(ethoxymethylene)-3-oxobutanoate (5c), ethyl 2-(ethoxymethylene)-3-oxo-4-phenylpropanoate (5d) afforded exclusively the corresponding 6-substituted pyridines (6b-d). Cyclization of 4 with 3-carbethoxybutane-2,4-dione (5e) gave 3-cyano-5-(ethoxycarbonyl)-4,6-dimethylpyridine-2(1H)-thione (6e)
氰基
硫代乙酰胺(4)与α-(乙氧基亚甲基)
乙酰乙酸乙酯(5b),4-乙氧基-2-(乙氧基亚甲基)-
3-氧代丁酸乙酯(5c),2-(乙氧基亚甲基)-3-氧代-4-苯基
丙酸乙酯的缩合(5d)仅提供相应的6-取代的
吡啶(6b-d)。用3-乙氧基
丁烷-2,4-二酮(5e)环化4,得到3-
氰基-5-(乙氧基羰基)-4,6-二
甲基吡啶-2(1H)-
硫酮(6e),而4与3-的反应carbethoxy-1-phenylpropane-1,3-dione(5f)产生两种产物,3-cyano-5-(ethoxy羰基)-4-methyl-6-phenylpyridine-2(1H)-thione(6f)和6-methyl -4-苯基异构体6g。6f和6g的结构分配是基于对6f和6g通过MeI / K2CO3处理制备的2-(甲
硫基)
烟酸酯(7f,g)的1H和13C NMR光谱分析得出的。
烟酸酯7b,dg转化为其相应的2,4-二
氨基吡啶并[2