Generation of [75Se]dimethyl selenide and the synthesis of [75Se]dimethyleselenonium compounds

Abstract

AbstractThe synthesis of various [75Se]selenonium compounds of biological interest is described. [75Se]Trimethylselenonium iodide (sp. Ac. 32 mCi/mmol), prepared from commercially available [75Se]selenocystine (Foster S. J. and Ganther H. E. ‐ Anal. Biochem. 137: 205–9, 1984.) was decomposed thermally, in a stream of nitrogen, to give [75Se]dimethyl selenide, which was trapped in nitromethane at −18°C. [75Se]Dimethyl selenide was reacted, in nitromethane solution, with various alkyl halides to give dimethylselenonium compounds of the type (CH3)2Se+‐R, where R = CH2CO2H, CH2H, CH2CO2C2H5, ‐(CH2)2CO2H and ‐(CH2)2CO2C2H5. [75Se]Methyl‐selenomethionine‐selenonium iodide was synthesized from [75Se]selenomethionine and methyl iodide in a mixture of formic and acetic acids at 25°C. [75Se]Selenocystine was reduced and methylated to give [75Se]‐methylselenocysteine, which was slowly converted to [75Se]dimethyl‐selenocysteineselenonium iodide by the same reaction.