Novel Glycosidation of 4-Demethoxyanthracyclinones by the Use of Trimethylsilyl Triflate. Syntheses of Optically Active 4-Demethoxydaunorubicin and 4-Demethoxyadriamycin

Optically pure (+)-4-demethoxydaunorubicin has been prepared by a novel glycosidation reaction of (+)-4-demethoxydaunomycinone with (-)-3-N-trifluoroacetyl-1,4-bis(O-p-nitrobenzoyl)-l-daunosamine in the presence of trimethylsilyl triflate, followed by sequential O- and N-deprotection reactions. Total synthesis of optically pure (+)-4-demethoxyadriamycin has been also accomplished by two different synthetic schemes, starting from (+)-4-demethoxydaunorubicin or by way of (+)-3'-N-trifluoroacetyl-4-demethoxyadriamycin. (+)-4-Demethoxyadriamycin prepared by our hands was fully characterized by its spectral properties.