Stereoselective Access to Functionalized Dihydrophenanthrenes via Reductive Cyclization of Biaryl Ene-Aldehydes

Abstract

Stereoselective access to 9-alkyl-10-hydroxy-9,10-dihydrophenanthrenes has been developed via the samarium(II) iodide mediated reductive cyclization of an ene-aldehyde appended to a biphenyl scaffold.

Visible-Light-Promoted 6π Photocyclization of ortho-Biaryl-Appended β-Ketoesters

“…To date, the reduction of biaryl dialdehyde or 9-phenanthrols is still one of the most important approaches toward this important class of compounds. For example, Suzuki and Uemura independently developed a SmI 2 -catalyzed intramolecular pinacol coupling strategy to obtain the trans -9,10-dihydrophenanthrene-9,10-diol from 2,2′-dicarbonyl-1,1′-biphenyls (Scheme A) . In 2021, Song and Wang reported a domino intramolecular [3 + 2] cycloaddition and ring-opening aromatization process between dialdehyde compounds and trans -4-hydroxy- l -proline or indoline-2-carboxylic acid for the efficient direct synthesis of substituted 9,10-dihydrophenanthren-9-ols (Scheme B) .…”