Synthesis of the AB Subunit of Angelmicin B through a Tandem Alkoxy Radical Fragmentation-Etherification Sequence

The synthesis of the tricyclic enone 2, corresponding to the AB subunit of the novel tyrosine kinase inhibitor angelmicin B, is described. The
strategy centers on an intramolecular Diels−Alder (IMDA) reaction on triene 4 to provide the complex decalin 3, which is elaborated to 2. Other
key steps are the formation of the THF ring in 2 through a tandem alkoxy radical fragmentation-etherification on the lactol derived from 3, and
the synthesis of 4 via a ring-closing ene-yne metathesis (RCEYM).