Total Synthesis of the Antitumor Antibiotic Basidalin

The
first synthesis of the tetronamide antibiotic basidalin was
accomplished in five steps and 39% overall yield from readily available
4-bromo-2-triiso­propyl­silyloxy­furan and 2-formyl-1,3-dithiane.
Highlights include: (i) regio- and stereocontrolled assemblage of
a pivotal (Z)-γ-ylidene-β-bromo­butenolide
intermediate by stereodirected vinylogous aldol condensation (SVAC),
(ii) installation of the amino group via aza-Michael addition/​elimination,
and crucially (iii) facile access to basidalin by late-stage dithiane
removal.