Diversity-oriented synthesis of 17-spirosteroids

A diversity-oriented synthesis (DOS) approach has been used to functionalize 17-ethynyl-17-hydroxysteroids through a one-pot procedure involving a ring-closing enyne metathesis (RCEYM) and a Diels–Alder reaction on the resulting diene, under microwave irradiations. Taking advantage of the propargyl alcohol moiety present on commercially available steroids, this classical strategy was applied to mestranol and lynestrenol, giving a collection of new complex 17-spirosteroids.

Synthesis of Atropisomeric MeOBIPHEP Analogues and Their Application in Silver-Catalyzed Cycloisomerization of Allenols

The preparation of novel MeOBIPHEP atropisomeric chiral congener ligands via an efficient palladium-catalyzed P–C coupling key step is described. We demonstrate that these palladium-catalyzed conditions are compatible with the brominated MeOBIPHEP backbone. The reaction conditions for asymmetric silver-catalyzed cycloisomerization of γ-allenols were optimized, leading to the first enantioselective catalytic system employing atropisomeric diphosphine ligands as the chiral inducer. The process follows a major 5-exo cyclization via addition of the alcohol moiety to the π-activated allenyl intermediate, leading to vinyltetrahydrofurans with enantiomeric ratios up to 91.5:8.5.