Total Synthesis of the Furaquinocins

A viable synthetic route to the furaquinocin-class antibiotics is described. The key steps include (1) Co-complex mediated stereospecific 1,2-shift of an alkynyl group (<b>9</b> → <b>6</b>) to establish the C(2)−C(3) stereochemical relationship, (2) efficient construction of furanonaphthalene <b>20</b> from the sodium carboxylate derived from ester <b>19</b>, and (3) stereoselective methylene transfer reaction to aldehyde <b>21</b> to establish the three contiguous stereogenic centers, C(2), C(3), and C(10). The stereodefined epoxide <b>23</b>, thus obtained, served as a versatile intermediate in divergent syntheses of four congeners of this class of natural products, furaquinocins A (<b>1a</b>), B (<b>1b</b>), D (<b>1d</b>), and H (<b>1h</b>), by changing the vinylic nucleophiles.