One-step enantioselective synthesis of (4S)-isosclerone through biotranformation of juglone by an endophytic fungus

We describe here a direct access to (4S)-isosclerone (+)-1, an important structural component of several natural products featuring a spirobisnaphthalene ring system. Starting with the commercially available 5-hydroxy-1,4- naphthalenedione (juglone), biotransformation by the isosclerone-producing endophytic fungus Paraconiothyrium variabile is described. The absolute configuration of (+)-1 was determined unambiguously using circular dichroism and by measurement of the optical rotation. Moreover, the biotransformations of other naphthalene derivatives were undertaken and led to the corresponding (4S)-hydroxy-1-tetralone. At last, this work brings some insights on the biosynthesis of natural tetralones.