Proprietary Synthesis of the C27–C35 Fragment of Eribulin and Its Elaboration toward the C14–C35 Subunit

Successful kilogram-scale preparation of the C27–C35 sulfide fragment of Eribulin was presented, which was elaborated with the C14–C26 fragment to produce a proprietary C14–C35 sulfide intermediate. The sulfide group was then oxidized to yield the known C14–C35 sulfone intermediate of Eribulin.