Multicomponent cyclocondensation of Meldrum's acid, 2-chlorobenzaldehyde, and N-(4-bromophenyl)-3-amino-3-thioxopropanamide in the presence of N-methylmorpholine afforded N-methylmorpholinium 3-[N-(4-bromophenyl)carbamoyl]-4-(2-chlorophenyl)-6-oxo-1,4,5,6-tetrahydropyridine-2-thiolate in 65% yield. When treated with dilute HCl, the thiolate easily transformed into N-(4-bromophenyl)-4-(2-chlorophenyl)-2-oxo-6-thioxopiperidine-5-carboxamide, which reacted with alkyl halides to give products of regioselective S-alkylation in high yields.
在
N-甲基吗啉存在下,梅尔杜姆酸、
2-氯苯甲醛和 N-(4-
溴苯基)-3-
氨基-3-
硫酮丙酰胺的多组分环缩合反应生成了
N-甲基吗啉鎓 3-[N-(4-
溴苯基)
氨基甲酰基]-4-(2-
氯苯基)-6-氧代-
1,4,5,6-四氢吡啶-2-
硫酸盐,收率为 65%。当用稀
盐酸处理时,
硫酸盐很容易转化为 N-(4-
溴苯基)-4-(2-
氯苯基)-2-氧代-6-
硫酮
哌啶-5-甲酰胺,该甲酰胺与烷基卤化物反应,得到高产率的区域选择性 S-烷基化产物。