A Scalable Process for the Synthesis of 1,2-Dialkyldiselanes and 1‑Alkaneselenols

A four-step telescoped process for the synthesis of 1-alkaneselenols entails (1) the rapid formation of potassium selenocyanate from potassium cyanide and selenium in methanol, (2) the nucleophilic substitution of bromoalkanes or alkyl tosylates with potassium selenocyanate, (3) the mild base-catalyzed conversion of the resultant 1-alkaneselenocyanates to 1,2-dialkyldiselanes (the Krief reaction), and (4) the reduction of the resultant 1,2-dialkyldiselanes with hypophosphorous acid to give the desired 1-alkaneselenols. The process has been used to produce 1-octaneselenol on a 10.4 mol scale. Nine examples of the process are described.