Synthesis of Two Diastereomeric C1–C7 Acid Fragments of Amphidinolactone B Using B ‐Alkyl Suzuki–Miyaura Cross‐Coupling as the Modular Assembly Step

The proposed structure of amphidinolactone B has an oxygenated stereogenic center at C6 whose absolute configuration remains unassigned. As part of our total synthesis program, two diastereomeric C1–C7 acid fragments have been synthesized from a common C6,C7‐diol intermediate. The latter was obtained from the two readily available chiral alkenyl/alkyl iodides using the “9‐MeO‐9‐BBN variant” of the B ‐alkyl Suzuki–Miyaura cross‐coupling reaction under the Pd(OAc) 2 –Aphos‐Y‐catalyzed reaction conditions (K 3 PO 4 ⋅3H 2 O, H 2 O, THF, r.t., 12 h, 75 %). The C6,C7‐diol was then transformed into two diastereomeric C6,C7‐epoxides through manipulation of the epoxide ring closure process. Finally, the epoxides reacted with dimethylsulfonium methylide (Me 2 S + CH 2 – ) to form, respectively, the corresponding allylic alcohols with the defined absolute configuration at C6.