8-Ethenyl-1-hydroxy-4-.beta.-D-ribofuranosylbenzo[d]naphtho[1,2-b]pyran-6-one and 8-ethenyl-1-hydroxy-4-(2'-deoxy-.beta.-D-ribofuranosyl)benzo[d]naphtho[1,2-b]pyran-6-one. Synthetic C-glycosides related to the gilvocarcin, ravidomycin, and chrysomycin antibiotics

Abstract

Syntheses of 8-ethenyl-1-hydrory-4-β-D-ribofuranosylbenzo[d]naphtho[1,2-b]pyran-6-one (1) and 8-ethenyl- 1-hydrory-4-(2'-deoxy-β-ribofuranosyl)benzo[d]naphtho[1,2-b]pyran-6-one (2) have been accomplished. These two compounds are the first synthetic C-glycosides structurally related to the gilvocarcin, ravidomycin, and chrysomycin antibiotic class which possess the aglycon substituents (hydroxyl at C-1 and ethenyl at C-8) considered critical for the photolytic nicking of DNA.Anthracycline C-glycoside 1 was prepared by a route involving Lewis acid-catalyzed C-glycosyl bond formation between the tetracyclic aglycon and 1,2,3,5-tetra-O-acetyl-D-ribose followed by construction of the aglycon 8-ethenyl substituent from the corresponding ethyl group by radical bromination-dehydrobromination.Synthesis of C-glycoside 2 utilized a different, complementary procedure for C-glycosyl bond formation by palladium-mediated coupling of an iodoaglycon derivative with 1,4-anhydro-2-deoxy-3-O-(tert-butyldiphenylsilyl)-D-erythro-pent-1-enitol,a furanoid glycal designed to form only β C-glycosyl bonds in this reaction