Ruthenium-SYNPHOS-Catalyzed Asymmetric Hydrogenations: an Entry to Highly Stereoselective Synthesis of the C15−C30 Subunit of Dolabelide A
摘要:
An efficient construction of the C15-C30 segment of the cytotoxic macrolide dolabelide A is described. The synthesis relies on ruthenium-SYNPHOS-mediated asymmetric hydrogenation reactions of beta-keto esters to generate the C19, C21, and C27 hydroxyl-bearing stereocenters with very high levels of enantio- and diastereoselectivity.
A Multifaceted Phosphate Tether: Application to the C15−C30 Subunit of Dolabelides A−D
摘要:
Construction of the C15-C30 subunit of dolabelide utilizing a temporary phosphate tether is described. Two routes are reported that make use of the orthogonal protecting- and leaving-group properties innate to phosphate esters. One route relies on a selective terminal oxidation, while a second utilizes a CM/selective hydrogenation sequence. Both routes depend on a highly regio- and diastereoselective cuprate addition to set the requisite stereochemistry at C22.