| 摘要 |
In one aspect, the present invention provides a protected ligand precursor having structure XXI wherein R8 is independently at each occurrence a protected hydroxy group, a protected C1-C3 hydroxyalkyl group, or a C1-C3 alkyl group, and b is 0-4; R9-R11 are independently at each occurrence hydrogen, a protected C1-C3 hydroxyalkyl group, or a C1-C3 alkyl group, with the proviso that at least one of R8-R11 is a protected hydroxy group or a protected C1-C3 hydroxyalkyl group; and R12 and R13 are independently at each occurrence acid sensitive protecting groups.
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