A mixture of R-9-acetamido-9- [1,1- (2,2-dimethylpropanedioxy) ethyl] -4,5-dihydro-6,13-dihydroxy -4,14- Methyl-14H-anthraceno [3,2-f] - [1,3] oxazolene-7,12-dione (Compound 4, R = CH3), 1200 g of 3N sulfuric acid aqueous solution and incubated at 60-70 ?? C for 8 hours. The pH of the solution was adjusted to 7-8 with aqueous sodium hydrogencarbonate solution, The combined chloroform layers were washed with water, dried, filtered and concentrated. The residue was stirred with isopropyl ether to give (+) - 9-amino-4-demethoxy-9-deoxo daunomycinone.
