[Synthesis and properties of carminomycinone derivatives]

The possibility of chemical modification of carminomycinone-aglycone (II) of carminomicin, a side product in the antibiotic production was studied. The methyl group C-14 was functionilized by introducing the bromine atom and performing a number of exchange reactions with the bromine atom. It was found that under definite conditions (1. 1 equiv. Br2in dioxane, 20 degrees, 24 hours) carminomycinone (II) was subjected to selective bromination into the side acetyl group with formation of 14-bromcarminomycinone (III). On interaction with anhydrous potassium acetate 14-bromcarminomycinone (III) yield 14-acetoxycarminomycinone (IV). In its turn the latter compound (IV) easily hydrolized to 14-oxycarminomycinone (V) in treatment with aqueous alkali or acid. 14-oxycarminomycinone (V) was also prepared with a high yield (80 per cent) by direct alkaline hydrolysis of 14-bromcarminomycinone (III) in treatment with 0.1N solution of sodium carbonate in a mixture of dioxane and water. The structure of 14-substituted derivatives of carminomycinone was proved by analytical and spectral data and confirmed by their transformation. Thus, according to the data of mass-spectrometry 14-oxycarminomycinone (V) had a molecular weight of 400 c. u. In treatment with an excess of acetic anhydride in pyridine it formed a hexa-acetyl derivative, i.e. 4, 6, 7, 9, 11, 14-hexa-acetyl-14-oxycarminomycinone (VI). The aglycones (III-V) prepared by us may serve a starting material in chemical synthesis, as well as biosynthesis of semi-synthetic preparations of the carminomycin series.