| 摘要 |
Compounds of the formula (I) A is OH or a carbonyl group, n is 0 or 1, R is an alkyl radical having from 1 to 4 carbon atoms, in particular methyl, ethyl, n-propyl, iso-propyl, n-butyl or t-butyl; or a residue of a hydroxy carboxylic acid, in particular the residue —CH(OH)COOH, —CH(OH)CH2COOH, —CH2CH(OH)COOH or —CH(OH)CH(OH)COOH; and R′ is independently selected from H or OH. |
