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Syntheses of radiolabelled forms of a novel histamine H 1 antagonist (SK&F 93944)
Author(s) -
Cashyap M M,
Mitchell M B,
Osborne D C,
Saunders D
Publication year - 1985
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.2580221206
Subject(s) - chemistry , methyl iodide , cyanamide , alkylation , yield (engineering) , histamine , iodide , medicinal chemistry , halogenation , organic chemistry , stereochemistry , catalysis , materials science , medicine , metallurgy
A novel histamine H 1 antagonist SK&F 93944 1 , 2‐[4‐(5‐bromo‐3‐methylpyrid‐2‐yl)butylamino]‐5‐(6‐methylpyrid‐3‐yl‐methyl)‐4(3H)‐pyrimidone, has been labelled with carbon‐14 in two different positions for use in metabolism and pharmacoinetic studies. The four stage synthesis of [pyrimidone‐2‐ 14 C] SK&F 93944 (7) from barium [ 14 C]cyanamide is described. The overall radiochemical yield was 38%. [butylamino‐4‐ 14 C] SK&F 93944 (14) was synthesised in four steps from [ 14 C]methyl iodide. The key steps in this synthesis were alkylation of 2‐lithio‐3‐methyl pyridine with [ 14 C]methyl iodide and the bromination of 4‐(3‐methyl‐2‐pyridyl)[4‐ 14 C]butylamine in a liquid sulphur trioxide/freon mixture. The overall radiochemical yield was 1.6% from [ 14 C]methyl iodide.