A 5'-(trifluoromethyl)anthracycline glycoside: synthesis of antitumor-active 7-O-(2,6-dideoxy-6,6,6-trifluoro-alpha-L-lyxo-hexopyranosyl) adriamycinone.

7-O-(2,6-Dideoxy-6,6,6-trifluoro-alpha-L-lyxo-hexopyranosyl)adriam ycinone (3), whose substituent at C-5' is a lipophilic trifluoromethyl group, has been prepared by coupling of 3,4-di-O-acetyl-2,6-dideoxy-6,6,6-trifluoro-alpha-L-lyxo-hexopyran osyl bromide (20) with 14-O-(tert-butyldimethylsilyl)adriamycinone under the Koenigs-Knorr conditions. The key step in this synthesis was the C-trifluoromethylation of 5-O-acetyl-2,3-di-O-benzyl-4-deoxy-aldehydo-L-erythro-pentose (10), derived from D-lyxose in 10 steps, with (trifluoromethyl)trimethylsilane in the presence of tetrabutylammonium fluoride, whereupon 1,1,1-trifluoro-L-arabino-hexitol (11) was obtained along with its 2-epimer. The synthetic product 3 showed remarkable antitumor activity in vivo in a low dose range compared to the analogs including doxorubicin. The fact may be ascribed to the presence of a trifluoromethyl group at C-5', suggesting the importance of the group in view of biological activity.