Progress of the total asymmetric synthesis of antascomicin B

by Walker, Brian; McIntosh, Matt C.

The purpose of this work is to describe the progress of the total asym. synthesis of antascomicin B. The antascomicins are among a few naturally occurring mols. that have been identified to bind FKBP12, similar to FK506 and rapamycin, but do not show immunosuppressive tendencies. The construction of the C(34)-C(22) fragment of antascomicin B is prepd. from a mono-reduced epoxide intermediate and includes an Ireland-Claisen rearrangement to afford the anti-relationship at the C(27)-C(26) stereocenters and directed Hydrogenation of the C(29) exo-cyclic double bond. Synthetic strategies and addnl. details to complete fragment by an allylic diazene rearrangement will be discussed.