Synthesis of (−)-Flavoskyrins by Catalyst-Free Oxidation of (R)-Configured Dihydroanthracenones in Aqueous Media and Its (Bio)synthetic Implications
2020
Mondal, Amit | De, Arijit | Husain, Syed Masood
A catalyst-free method for the synthesis of dimeric (−)-flavoskyrins has been developed. It involves the autoxidation of chemoenzymatically synthesized (R)-configured dihydroanthracenones in the presence of molecular oxygen in buffer of pH 6.0 followed by spontaneous [4 + 2] cycloaddition in stereocontrolled exo-anti fashion to form (−)-flavoskyrins. The method is applied to obtain several homo- as well as heterodimerized flavoskyrins (nine examples) in 27–72% yield and implies the involvement of a similar pathway in the (bio)synthesis of modified bisanthraquinones and their analogues.
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