This makes it an attractive starting point for the synthesis of
analogues based upon its unique scaffold. An initial attempt
was disappointing because all reported analogues exhibited
decreased biological activities.206 Waldmann’s group used
their BIOS methodology, described in section 4.2.2, to
synthesize a focused library of 50 R,-unsaturated δ-lactones
that yielded several unique modulators of cell-cycle progression.207
No additional derivatives of pironetin have yet been
reported as candidate leads.