TOTAL SYNTHESIS OF THE FURAQUINOCINS

A viable synthetic route to the furaquinocin-class antibiotics is desc ribed. The key steps include (1) Go-complex mediated stereospecific 1, 2-shift of an alkynyl group (9 --> 6) to establish the C(2)-C(3) stere ochemical relationship, (2) efficient construction of furanonaphthalen e 20 from the sodium carboxylate derived from ester 19, and (3) stereo selective methylene transfer reaction: to aldehyde 21 to establish the three contiguous stereogenic centers, C(2), C(3), and C(10). The ster eodefined epoxide 23, thus obtained, served as a versatile intermediat e in divergent syntheses of four congeners of this class of natural pr oducts, furaquinocins A (1a), B (1b), D (1d), and H (1h), by changing the vinylic nucleophiles.