H. Kim, Y. Kurasawa, Chiemi Yoshii
May 1, 1990
Citations
0
Influential Citations
18
Citations
Journal
Journal of Heterocyclic Chemistry
Abstract
The reaction of the 2-substituted 6-chloroquinoxaline 4-oxides 1a or 1b with 2-fold molar amount of methyl propiolate resulted in the 1,3-dipolar cycloaddition reaction to give 8-chloro-1,3-bismethoxycarbonyl-4-(piperidin-1-yl)pyrrolo[1,2-a]quinoxaline 4a or 8-chloro-1,3-bismethoxycarbonyl-4-(morpholin-4-yl)pyrrolo-[1,2-a]quinoxaline 4b, respectively. Compound 4a or 4b was transformed into 8-chloro-3-methoxycarbonyl-4-(piperidin-1-yl)pyrrolo[1,2-a]quinoxaline 5a or 8-chloro-3-methoxycarbonyl-4-(morpholin-4-yl)pyrrolo[1,2-a]-quinoxaline 5b, respectively. The structure of 4a,b was confirmed by the NOE measurement among the C1-H, C2-H and C9-H proton signals of 5a,b. An additional reaction mechanism was proposed for the ring transformation of isoxazolo[2,3-a]quinoxalines into pyrrolo[1,2-a]quinoxalines.