A stereoselective synthesis of the C(3)-C(13) and C(14)-C(24) fragments of macrolactin A

Synthetic studies towards the C(3)‐C(13) and C(14)‐C(24) segments (3,4) of the potent antiviral and antitumor compound macrolactin A (1) are presented. Compound 3 was constructed via a convergent and facile approach, exploiting Wittig olefination to generate the sensitive E, Z‐diene moiety. Compound 4 was synthesized from the chiral‐pool derived sulfone 39a via an α‐alkylation‐desulfonation reaction sequence. Cu(II)‐catalyzed coupling of a Grignard reagent with an allylic bromide and Julia olefination were also investigated for the preparation of compound 4.