Thermal Reaction of Imidazolium N-Vinylimino Ylides: Formation of Mesomeric Betaines, Imidazopyridaziniumides, via Back-Donated 1,6-Cyclization.
作者:Yoshiro MATSUDA、Makoto YAMASHITA、Kimitoshi TAKAHASHI、Shizuki IDE、Takahiro ITOU、Chieko MOTOKAWA、Yasushige CHIYOMARU
DOI:10.1248/cpb.42.454
日期:——
The reaction of N-aminoimidazolium salts (4, 5) with polarized olefins (2a-d, 3a, b) in the presence of K2CO3 in EtOH gave the corresponding imidazolium N-vinylimino ylides (6, 7). Thermolyses of the N-vinylimino ylides (6c-f, 7a-c) afforded mesomeric betaines (8a-d, 9a, b, 10a, b). Treatment of the salt (5) with polarized olefins (2b-d, 3c) in the presence of K2CO3 in EtOH directly yielded mesomeric betaines (9c-d, 10c), while in EtOH, the reaction of the salt (5) with polarized olefins (2e, 3d) in the presence of K2CO3 gave pyrazoles (11a, b). The formation of mesomeric betaines is suggested to proceed via back-donated 1, 6-cyclization.
在 K2CO3 存在下,N-氨基咪唑鎓盐(4、5)与极化烯烃(2a-d、3a、b)在 EtOH 中发生反应,生成相应的咪唑鎓 N-乙烯亚氨基酰化物(6、7)。对 N-乙烯亚氨基酰亚胺(6c-f、7a-c)进行热解可得到中间体甜菜碱(8a-d、9a、b、10a、b)。在有 K2CO3 存在的情况下,在 EtOH 溶液中将盐 (5) 与极化烯烃 (2b-d, 3c) 反应,可直接生成中生甜菜碱类化合物 (9c-d, 10c);而在有 K2CO3 存在的情况下,在 EtOH 溶液中将盐 (5) 与极化烯烃 (2e, 3d) 反应,可生成吡唑类化合物 (11a, b)。据推测,中间体甜菜碱的形成是通过背负式 1,6-环化反应进行的。