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Preparation of pyridostigmine bromide labeled with carbon-14 and tritium1

✍ Scribed by J. A. Kepler; C. E. Twine; R. D. Austin

Publisher
John Wiley and Sons
Year
1992
Tongue
French
Weight
545 KB
Volume
31
Category
Article
ISSN
0022-2135

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✦ Synopsis

Abstract

[2‐^14^C]Pyridostigmine bromide was prepared in 17.6% radiochemical yield with specific activity of 18 mCi/mmol. The reaction sequence involved preparation of 2‐furan[^14^C]carboxylic acid by carbonation of 2‐lithiofuran, followed by conversion to 2‐amino[^14^C]methyl furan by lithium aluminum hydride reduction of its carboxamide. Oxidative rearrangement of 2‐amino[^14^C]methylfuran gave 3‐hydroxy[2‐^14^C]pyridine which was converted to [2‐^14^C]pyridostigmine bromide by reaction with dimethylcarbamyl chloride and quarternization with bromomethane. Pyridostigmine bromide labeled in the methyl group of the carbamate function was prepared in 73% yield with specific activity of 37.6 mCi/mmol by reaction of bis‐3‐pyridyl carbonate with [^14^C]dimethylamine followed by quarternization with bromomethane. [6‐^3^H]‐Pyridostigmine bromide with specific activity of 22.5 mCi/mmol was prepared by catalytic halogen‐tritium replacement of 2,6‐dibromo‐3‐dimethylcarbamyloxypyridine followed by quarternization with bromomethane and back‐exchanging the labile 2‐tritium.

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