ANTHRACYCLINONES .5. GLUCOSACCHARINO-1,4-LACTONE AS A CHIRAL TEMPLATE FOR THE SYNTHESIS OF NEW ANTHRACYCLINONES

Alkylation of dimethoxybenzene 16 with the chiral aldehyde derivative 14 prepared in six steps from alpha-D-glucosaccharino,1,4-lactone 3 afforded the adduct 17. After suitable transformation of 17, A ring closure was stereoselectively performed using SnCl4 at -70-degrees-C, giving 20. The tetralin-type quinone monoketal 23 obtained from 20 was then condensed with 27, and complete deprotection of anthracyclinones 28 and 29 led to 9-deacetyl-8(R)-hydroxy-9-methyl-4-demethoxydaunomycinone (6). On the other hand, 39, easily obtained from 14, was condensed with leucoquinizarin 31 to give after oxidation, intramolecular Marschalk reaction and benzylic deoxygenation, the corresponding 7-deoxyaglycon 7.