A Lewis acid-promoted cyclization of ethenetricarboxylate derivative aromatic compounds. Novel syntheses of oxindoles and benzofuranones via Friedel-Crafts intramolecular Michael addition.
A novel cyclization reaction of ethenetricarboxylate derivative aromatic compounds in the presence of various Lewis acids gave benzo-annulated cyclic compounds such as oxindole and benzofuran derivatives via Friedel-Crafts intramolecular Michael addition in high yields. For example, the reaction of diethyl 2-[(N-methyl-N-phenylcarbamoyl)methylene]malonate (1a) in the presence of ZnCl2 at room temperature gave diethyl 2-(1-methyl-2-oxoindolin-3-yl)malonate (2a) in 98% yield. The reactions also proceeded with a catalytic amount of a Lewis acid such as AlCl3, ZnCl2, ZnBr2, Sc(OTf)3, or InBr3.
Yamazaki
Shoko
S
Department of Chemistry, Nara University of Education, Takabatake-cho, Nara, 630-8528, Japan. yamazaks@nara-edu.ac.jp
Morikawa
Satoshi
S
Iwata
Yuko
Y
Yamamoto
Machiko
M
Kuramoto
Kaori
K