Asymmetric Synthesis of the Aromatic Fragment of Sespendole

Sespendole is an indole sesquiterpene
alkaloid bearing two isoprenyl
groups, one of which is highly oxidized. Herein, we disclose an eight-step
synthesis of the aromatic fragment of sespendole in an optically pure
form, starting from 4-bromo-2-fluoronitrobenzene. The key steps were a Claisen rearrangement at room
temperature for introduction of the prenyl group and a coupling between
the dianion generated from prenylated bromo-N-tosylanilide
and a chiral epoxy aldehyde.