Asymmetric Synthesis of Nodulones C & D by Chemoenzymatic Approach gives Insight into their Biosynthesis

The first asymmetric total synthesis of fungal secondary metabolites, (R)-nodulone C (4) and trans-nodulone D (5) has been reported through the chemoenzymatic approach. The strategy utilizes NADPH-dependent naphthol reductases of Magnaporthe grisea for the reduction of putative biosynthetic substrates, synthesized non-enzymatically in multiple steps. A dihydronaphthalenone 32 and cis-nodulone D (30) has also been synthesized chemoenzymatically. The work implies for similar steps during the biosynthesis of nodulones and their analogs with the involvement of tetrahydroxynaphthalene reductase related enzyme(s).