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 (9 → 6) to establish the C(2)−C(3) stereochemical relationship, (2) efficient construction of furanonaphthalene 20 from the sodium carboxylate derived from ester 19, and (3) stereoselective methylene transfer reaction to aldehyde 21 to establish the three contiguous stereogenic centers, C(2), C(3), and C(10). The stereodefined epoxide 23, thus obtained, served as a versatile intermediate in divergent syntheses of four congeners of this class of natural products, furaquinocins A (1a), B (1b), D (1d), and H (1h), by changing the vinylic nucleophiles.