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A nine‐step synthesis of [ 14 C]flupirtine maleate labeled in the pyridine ring
Author(s) -
Choi Yong M.,
Kucharczyk Norbert,
Sofia R. Duane
Publication year - 1987
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.2580240102
Subject(s) - chemistry , pyridine , hydrochloride , reagent , yield (engineering) , medicinal chemistry , carbamic acid , nitro , potassium cyanide , stereochemistry , cyanide , organic chemistry , materials science , alkyl , metallurgy
A nine‐step procedure for microscale synthesis of ethyl 2‐amino‐6‐{[(4‐fluorophenyl)methyl]amino}‐3‐pyridinyl‐2,6‐ 14 C carbamate maleate [ 10 ], [ 14 C]flupirtine maleate, was developed. The synthesis started with the readily avaiable and economical reagents, potassium cyanide‐ 14 C and 1,3‐dibromopropane making the following intermediates: glutaronitrile‐ 14 C [ 2 ], glutarimide‐ 14 C [ 3 ], 2,6‐dichloropyridine‐2,6‐ 14 C [ 4 ], 2,6‐dichloro‐3‐nitro‐pyridine‐2,6‐ 14 C [ 5 ], 2‐amino‐3‐nitro‐6‐chloropyridine‐2,6‐ 14 C [ 6 ], 2‐amino‐3‐nitro‐6‐( p ‐fluorobenzylamino)pyridine‐2,6‐ 14 C [ 7 ], 2,3‐diamino‐6‐( p ‐fluoro‐benzylamino)pyridine‐2,6‐ 14 C [ 8 ], and ethyl 2‐amino‐6‐{[4‐fluoropheny(l)‐methyl]amino}‐3‐pyridinyl‐2,6‐ 14 C carbamic acid ester hydrochloride [ 9 ]. The overall yield was 6.3% (5.4 mCi), and the radioactivity was 99.8% as determined by high performance liquid chromatogrphy and liquid scintillation counting.