kanglemycin A

20-[1-(3-Carboxy-2,2-dimethyl-1-oxopropoxy)ethyl]-20-demethyl-27-O-demethyl-1,4-dideoxy-27-O-(2,6-dideoxy-3-O,4-O-methylene-β-D-ribo-hexopyranosyl)-1,4-dihydro-1,4-dioxorifamycin