Synthesis, isolation, and characterization of ABT-578 equilibrium isomers

ABT-578, an anti-restenosis agent exists as two isomers, a major pyran form and a minor oxepane form. The existence of the two isomeric forms was established by isolation and equilibration studies under buffered and physiological conditions. Finally their structures were confirmed by converting the major pyran form to the oxepane form by synthesis, isolation, and characterization.