A Concise and Convergent Total Synthesis of Two Novel Cytotoxic Hydroquinones, Lanneaquinol and (R)-2′-Hydroxylanneaquinol

Abstract

A short and efficient approach for the total synthesis of two novel cytotoxic hydroquinones, lanneaquinol (1) and (R)-2′-hydroxylanneaquinol (2) isolated from the organic extract of the plant Lannea welwitschii, has been developed. Enantioselective organocatalytic McMillan hydroxylation has been successfully utilized for the creation of the stereogenic center bearing the OH group of (R)-2′-hydroxylanneaquinol (2). The hydroquinone core was constructed through the alkylation of cyclohexane-1,4-dione with a corresponding aldehyde. Both hydroquinone natural products can be synthesized by a mere change in the synthetic strategy.