Chemoenzymatic Routes to Enantiomerically Enriched and Polyoxygenated Perhydro-3,5a-methanoindeno[4,5‑<i>c</i>]furans Related to the Tashironin Class of Sesquiterpenes

The alcohol 12, which is available in eight steps from the enzymatically derived cis-1,2-dihydrocatechol 8, engages in an intramolecular alkoxy radical-mediated remote functionalization reaction to form the tetrahydrofuran 13, thus establishing the perhydro-3,5a-methanoindeno­[4,5-c]­furan framework associated with the biologically active tashironins. Various manipulations of compound 13 and certain derivatives allow for the formation of compounds bearing strong structural resemblances to the title natural products.