SYNTHESIS OF HIGH SPECIFIC ACTIVITY [(CO)-C-14] METHYL ISOCYANATE ANDITS USE IN THE PREPARATION OF [(CO)-C-14] ESERINE, [(CO)-C-14] CARBARYL AND [(CO)-C-14] IPMU

The preparation of [(CO)-C-14] methyl isocyanate from [1-C-14] acetyl chloride and activated sodium azide through the Curtius rearrangement was optimized (50% yield/[1-C-14] sodium acetate-50 mCi/mmol) and the reagent immediately used for the synthesis of [(CO)-C-14] eserine, [(C O)-C-14] carbaryl and [(CO)-C-14] IPMU. The condensation of methyl iso cyanate with eseroline in the presence of triethylamine does not give rise to eserine but to the isomeric urea derivative (3) under bar.