Concise syntheses of L-selenomethionine and of L-selenocystine using radical chain reactions

L-Selenomethionine and L-selenocystine were prepared in high overall yields from protected L-glutamic and L-aospartic acid derivatives respectively. Irradiation of the mixed anhydrides (esters) derived from 4 (e.g. 15) in the presence of dimethyldiselenide provided the protected L-selenomethionine 16 directly. We have shown that triselenocyanide Se₃(CN)₂ can serve as an efficient selenocyanating agent for radicals; the selenocyanide group is a good precursor for the diselenide moiety of L-selenocystine.