Enantioselective reductive multicomponent coupling reactions between isatins and aldehydes

A reductive coupling of two different carbonyls via a polar two-electron reaction mechanism was developed and the stereochemical outcome of this multicomponent process is precisely controlled by a chiral triaminoiminophosphorane

Construction of Divergent Fused Heterocycles via an Acid-Promoted Intramolecular <i>ipso</i>-Friedel–Crafts Alkylation of Phenol Derivatives

Two different cascade cyclization processes were developed using aryl group-substituted propargyl alcohol derivatives with a <i>p</i>-hydroxybenzylamine unit as common substrates. Using TFA as an acid promoter, an intramolecular <i>ipso</i>-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

Acid-promoted Cascade Cyclization to Produce Fused-polycyclic Indole Derivatives

An acid-promoted novel cascade cyclization is described. Using 8 equiv of trifluoroacetic acid or a catalytic amount of Lewis acid as the promoter, structurally diverse polycyclic cyclopenta[<i>b</i>]indoles were obtained in moderate to excellent yield. This cascade process was extremely effective for the synthesis of 8-membered ring-fused cyclopenta[<i>b</i>]indole derivatives