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Synthesis of [1,3,5‐ 13 C 3 ]benzoic acid and [2,4,6,7‐ 13 C 4 ]benzoic acid from 13 C‐labelled sodium pyruvates
Author(s) -
Akira Kazuki,
Baba Shigeo
Publication year - 1992
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.2580310206
Subject(s) - chemistry , decarboxylation , benzoic acid , sulfuric acid , sodium hydroxide , sodium , potassium permanganate , nuclear magnetic resonance spectroscopy , nuclear chemistry , medicinal chemistry , inorganic chemistry , organic chemistry , catalysis
The synthesis of [1,3,5‐ 13 C 3 ]‐ and [2,4,6,7‐ 13 C 4 ]benzoic acid ( 5a and 5b ) from [2‐ 13 C]‐ and [3‐ 13 C]sodium pyruvate ( 1a and 1b ), for in vitro and in vivo tracer studies using 13 C nuclear magnetic resonance (NMR) spectroscopy, is reported. After condensation of 1 to [ 13 C]methyldihydrotrimesic acids 2 using sodium hydroxide, decarboxylation to [ 13 C]uvitic acid 3 was carried out using conc. sulfuric acid. Additional decarboxylation of 3 was achieved with cupric oxide and quinoline, and the resulting [ 13 C]toluenes 4 were effectively trapped, using a simplified decarboxylation apparatus. Compounds 4 were subsequently oxidized to 5 using potassium permanganate without further purification. The overall yields of 5 from 1 were 26–28 %, with isotopic purities of 96–98 %. In addition, the assignments for 13 C NMR signals of benzoic acid were first substantiated.