title: Electroreductive Intermolecular Coupling of Coumarins with Benzophenones: Synthesis of 4-(2-Hydroxyphenyl)-5,5-diaryl-γ-butyrolactones, 2-(2,2-Diaryl-2,3-dihydrobenzofuran-3-yl)acetic Acids, and 4-(Diarylmethyl)coumarins.
abstract: The electroreductive coupling of coumarins with benzophenones in the presence of TMSCl gave adducts reacted at the 4-position of coumarins as trimethylsilyl ethers. From 3-methylcoumarin, 3,4-cis-adducts were formed stereoselectively. The de-trimethylsilylation of the adducts with 1 M HCl aq or TBAF in THF at 25 °C produced 4-(2-hydroxyphenyl)-5,5-diaryl-γ-butyrolactones. The γ-butyrolactones were further transformed to 2-(2,2-diaryl-2,3-dihydrobenzofuran-3-yl)acetic acids by treatment with 1 M HCl aq at reflux temperature. The de-trimethylsilylation of the adducts with 1 M HCl in MeOH afforded 2-(2,2-diaryl-2,3-dihydrobenzofuran-3-yl)acetic acid methyl esters. The de-trimethylsiloxylation of the adducts or dehydration of the γ-butyrolactones brought about 4-(diarylmethyl)coumarins.
authors.affiliation: Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University , 4-101, Koyama-cho Minami, Tottori 680-8552, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Kise
authors.affiliation: Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University , 4-101, Koyama-cho Minami, Tottori 680-8552, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Hamada
authors.affiliation: Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University , 4-101, Koyama-cho Minami, Tottori 680-8552, Japan.
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Sakurai