Bioinspired Total Synthesis and Stereochemical Revision of the Fungal Metabolite Pestalospirane B

The total synthesis of both enantiomers of pestalospirane B, <b>2</b>, has been achieved using a bioinspired tandem dimerization–spiroketalization reaction. Electronic circular dichroism (ECD) and X-ray analysis were used to revise the absolute stereochemistry of the natural product pestalospirane B from 3<i>S</i>, 3′<i>S</i>, 12<i>R</i>, 12′<i>R</i> to its enantiomer 3<i>R</i>, 3′<i>R</i>, 12<i>S</i>, 12′<i>S</i>.