Stereo flexible synthesis of the C8-C23 fragment of antarlides, androgen receptor antagonists.

A practical and efficient synthesis of the C8-C23 fragment of antarlides A-H, incorporating six stereocenters and a conjugated diene, is reported. A strategic combination of synthetic methods, including CBS reduction, Evans' aldol reaction, Keck-Maruoka allylation, and enzymatic resolution, enabled the selective introduction of these stereocenters. Furthermore, the pivotal coupling of key fragments is successfully executed through a Julia-Kocienski olefination reaction, connecting the C8-C14 and C15-C23 subunits.