A Biomimetic Synthesis of Racemic Dihydroanthracen-1(2H)-ones Using Sodium Borohydride in Water

Article abstract of DOI:10.1002/ejoc.202000096

Herein, we report a single step synthesis of racemic dihydroanthracenones by the reduction of anthraquinones using NaBH₄ and Na₂S₂O₄ in water. The racemic mixture is utilized to determine the enantiomeric excess for the chiral dihydroanthracenones reportedly synthesized by the chemoenzymatic reduction of anthraquinones. The results show > 99percent ee for the putative biosynthetic intermediates, (R)-configured dihydroanthracenones obtained through chemoenzymatic reduction of emodin, lunatin, and citreorosein using MdpC of Aspergillus nidulans or PHAR of Cochliobolus lunatus. This also implied for the confirmation about the optical purity of the natural products which are synthesized using chiral dihydroanthracenones.