Abstract:
The enantioselective synthesis of (1R,3R)-deoxynanaomycin A (4) is reported. The key step involves introduction of the stereocenter in (S)-homoallylic alcohol 10a using an asymmetric allylation of aldehyde 9. Lithium-halogen exchange of bromo acetate 11 triggered rapid intramolecular cyclization furnishing lactol 12 that underwent silane-mediated reduction providing (1R,3S)-naphthopyran 13. Dihydroxylation and oxidative cleavage gave aldehyde 15 that underwent two successive oxidations delivering (1R,3R)-deoxynanaomycin A (4) in high enantiopurity and an overall 7% yield over 12 steps from 1-naphthol (5).