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Synthesis of N1′‐([ 11 C]methyl)naltrindole ([ 11 C]MeNTI): A radioligand for positron emission tomographic studies of delta opioid receptors
Author(s) -
Lever John R.,
Kinter Chris M.,
Ravert Hayden T.,
Musachio John L.,
Mathews William B.,
Dannals Robert F.
Publication year - 1995
Publication title -
journal of labelled compounds and radiopharmaceuticals
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.432
H-Index - 47
eISSN - 1099-1344
pISSN - 0362-4803
DOI - 10.1002/jlcr.2580360206
Subject(s) - chemistry , naltrindole , radiosynthesis , hydrogenolysis , ammonium hydroxide , radioligand , radiochemistry , carbon 14 , yield (engineering) , alkylation , nuclear chemistry , medicinal chemistry , organic chemistry , opioid receptor , opioid , receptor , in vivo , biochemistry , microbiology and biotechnology , materials science , catalysis , physics , quantum mechanics , metallurgy , biology
A delta opioid receptor antagonist, N1′‐methylnaltrindole (MeNTI), has been labeled with carbon‐11. The precursor for radiolabeling was prepared in 71% yield by benzylation of the phenolic moiety of naltrindole. Alkylation of the indole nitrogen using [ 11 C]iodomethane and aqueous tetra( n ‐butyl)ammonium hydroxide at 80 °C in dimethylformamide followed by hydrogenolysis (H 2 , 10% Pd‐C) of the benzyl protecting group gave [ 11 C]MeNTI. The average (n = 10) time for radiosynthesis, HPLC purification and formulation was 24 min from end‐of‐bombardment. [ 11 C]MeNTI of high radiochemical purity was obtained at end‐of‐synthesis with an average specific activity of 2050 mCi/μmol and radiochemical yield, based on [ 11 C]iodomethane, of 6%.