title: Construction of divergent fused heterocycles via an acid-promoted intramolecular ipso-Friedel-Crafts alkylation of phenol derivatives.
abstract: Two different cascade cyclization processes were developed using aryl group-substituted propargyl alcohol derivatives with a p-hydroxybenzylamine unit as common substrates. Using TFA as an acid promoter, an intramolecular ipso-Friedel-Crafts alkylation of phenol derivatives, formation of an iminium cation via a rearomatization-promoted C-C bond cleavage, an aza-Prins reaction, and a 6-membered ring formation proceeded sequentially, producing a variety of fused-tricyclic dihydroquinoline derivatives in 45-99% yield. In addition, a one-pot sequential silver acetate-catalyzed hydroamination/etherification-acid-promoted skeletal rearrangement was examined using the same series of substrates, affording fused-tricyclic indole/benzofuran derivatives in 66-89% yield.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Chiba University , 1-8-1, Inohana, Chuo-ku, Chiba 260-8675, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Yokosaka
authors.forename: Naoki
authors.initials: N
authors.lastname: Shiga
authors.forename: Tetsuhiro
authors.initials: T
authors.lastname: Nemoto
authors.forename: Yasumasa
authors.initials: Y
authors.lastname: Hamada
mesh_terms: D000143:Acids / Q000737:chemistry*; D000478:Alkylation; D003500:Cyclization; D006571:Heterocyclic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D010636:Phenols / Q000737:chemistry*
chemical_list: D000143:Acids; D006571:Heterocyclic Compounds; D010636:Phenols