Preparation of pyridostigmine bromide labeled with carbon-14 and tritium was written by Kepler, J. A.;Twine, C. E.;Austin, R. D.. And the article was included in Journal of Labelled Compounds and Radiopharmaceuticals in 1992.Safety of 2,6-Dibromo-3-hydroxypyridine This article mentions the following:
[2-14C]Pyridostigmine bromide (I, X = 14C, R = Me, R1 = H) was prepared in 17.6% radiochem. yield with specific activity of 18 mCi/mmol. The reaction sequence involved preparation of 2-furan[14C]carboxylic acid by carbonation of 2-lithiofuran, followed by conversion to 2-amino[14C]methylfuran by lithium aluminum hydride reduction of its carboxamide. Oxidative rearrangement of 2-amino[14C]methylfuran gave 3-hydroxy[2-14C]pyridine which was converted to [2-14C]pyridostigmine bromide by reaction with dimethylcarbamyl chloride and quaternization with bromomethane. Pyridostigmine bromide I (X = C, R = 14CH3, R1 = H) labeled in the Me 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 [14C]dimethylamine followed by quaternization with bromomethane. [6-3H]Pyridostigmine bromide (I, X = C, R = Me, R1 = 3H) with specific activity of 22.5 mCi/mmol was prepared by catalytic halogen-tritium replacement of 2,6-dibromo-3-dimethylcarbamyloxypyridine followed by quaternization with bromomethane and back-exchanging the labile 2-tritium. In the experiment, the researchers used many compounds, for example, 2,6-Dibromo-3-hydroxypyridine (cas: 6602-33-1Safety of 2,6-Dibromo-3-hydroxypyridine).
2,6-Dibromo-3-hydroxypyridine (cas: 6602-33-1) belongs to pyridine derivatives. Pyridine has a conjugated system of six π electrons that are delocalized over the ring. The molecule is planar and, thus, follows the Hückel criteria for aromatic systems. Several pyridine derivatives play important roles in biological systems. While its biosynthesis is not fully understood, nicotinic acid (vitamin B3) occurs in some bacteria, fungi, and mammals.Safety of 2,6-Dibromo-3-hydroxypyridine