Synthesis and authentication of iodoazidophenpyramine, a photoaffinity reporter ligand previously used for histamine H1-receptor labelling

Article abstract of DOI:10.1002/ardp.19953280909

The synthesis is described of aminophenpyramine (7) (N-{5-[2-(4-aminophenyl)ethanamido]pentanyl}-N'-(4-methoxybenzyl)-N- methyl-N'-(2-pyridinyl)-1,2-ethandiamine), its monoiodo- and diiodo-derivatives (8 and 9), and iodoazidophenpyramine (1). The last compound is synthesised by two different routes to confirm the identity of the [¹²⁵I]iodinated ligand previously made only in solution and used for characterisation of the hitamine H₁-receptor protein. The procedures employ the novel intermediates 4-amino-3-iodo-phenylacetic acid (11) and 4-azido-3-iodo-phenylacetic acid (13). They have general applicability to the synthesis of non-radioactive iodinated photoaffinity receptor ligands which may be required for chemical authentication of the corresponding radiolabelled compounds.