Electroreductive coupling of phthalimides with alpha,beta-unsaturated esters: unusual rearrangement of resulting silyl ketene acetals.
The electroreductive intramolecular coupling of phthalimides with alpha,beta-unsaturated esters in the presence of chlorotrimethylsilane and subsequent desilylation of resulting silyl ketene acetals with TBAF gave five- and six-membered trans-cyclized products stereospecifically. The silyl ketene acetals were readily rearranged to benzoindole and tetrahydrobenzoquinoline by standing or treatment with a Lewis acid under open-air conditions. The electroreductive intermolecular coupling of N-methylphthalimide with methyl acrylate also proceeded.
Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University, Koyama, Tottori 680-8552, Japan. kise@bio.tottori-u.ac.jp
Naoki
N
Kise
Shinsaku
S
Isemoto
Toshihiko
T
Sakurai