Stereoselective synthesis of (+)-SCH 351448: A unique ligand system for sodium, calcium, and other cations

(+)-SCH 351448 [Na(super +)salt A] was synthesized employing ring-closing olefin metathesis reaction of an open diene diester intermediate for construction of the 28-membered macrodiolide structure. Under acidic conditions, SCH 351448 [Na(super +)salt A] was the most stable complex, but SCH 351448 [Ca(super 2+) salt] and [Na(super +)salt B] appear to be physiologically important species.