3-O-(4-Hydroxyisovaleroyl)maytansinol

3-O-(3-Hydroxymethylbutanoyl)maytansinol

3-O-De[2-[methyl(acetyl)amino]-1-oxopropyl]-3-O-(3-hydroxymethylbutanoyl)maytansine

3-De[2-[acetyl(methyl)amino]-1-oxopropyloxy]-3-[3-(hydroxymethyl)butyryloxy]maytansine

Maytansine, O3-de2-(acetylmethylamino)-1-oxopropyl-O3-(4-hydroxy-3-methyl-1-oxobutyl)-