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. Author manuscript; available in PMC: 2012 Jul 20.
Published in final edited form as: Bioconjug Chem. 2011 Jun 16;22(7):1270–1278. doi: 10.1021/bc1004284

Scheme 1a. Synthetic Route for Heterobivalent Ligands (htBVLs).

Scheme 1a

aThe inset shows the sequence of MSH(7) and CCK(6) ligands and the structure of the PEGO linker (20 atoms). The reagents for each step are as follows: (i) Fmoc-amino acid-OH (3 equiv), HOCt (3 equiv), diisopropylcarbodiimide (3 equiv); (ii) 50% Ac2O in pyridine; (iii) 20% piperidine/DMF; (iv) (a) diglycolic anhydride (10 equiv) in DMF, (b) CDI (20 equiv) in anhyd. DMF, (c) 4,7,10-trioxa-1,13-tridecaneamine (20 equiv) in anhyd. DMF; (v) TFA/H2O/Thioanisole/Triisopropylsilane/Ethanedithiol 82.5:5:5:5:2.5; m is 3, 6, 9, 12, or 15; n is 1 or 2; o is 3, 6, 12, or 18.