Asymmetric Synthesis of the Fully Functional Macrolide Core of Salicylihalamide: Remote Control of Olefin Geometry during RCM
journal contributionposted on 27.10.2000, 00:00 by Alois Fürstner, Oliver R. Thiel, Gaetano Blanda
A catalysis-based approach to the core region 24 of the antitumor agents salicylihalamides A and B is reported. Key steps are two asymmetric hydrogenations of β-keto esters 13 and 16 catalyzed by [(R)-BINAP·RuCl2]2·NEt3 and an RCM-based macrocyclization effected by the NHC-containing ruthenium carbene 21. The stereochemical outcome of the latter reaction is controlled by remote substituents on the phenolic OH group of the cyclization precursor 23.