Total Synthesis of the Lycopodium Alkaloid dl-Serratinine

Abstract

Total synthesis of dl-serratinine (1 : dl-form) has been completed as follows. The Wittig reaction of the aldehyde (6) with diethylcyanomethylphosphonate gave the conju-gated nitrile (7) which was subjected to hydrogenation, followed by NaBH₄-CoCl₂ reduction to provide the primary amine (10). Treatment of (10) with NCS and Cu₂Cl₂ gave the aziridine A (11) and the aziridine B (12). The aziridine A was derived to the aziridinium salt (14) via the primary alcohol (13) and its tosylate, and the reaction of 14 with AcOK afforded the triacetate (15). Hydrolysis of 15, followed by oxidation with Jones'reagent gave the triketone (18). Finally, reduction of 18 with NaBH₄ afforded dl-serrat-inine (1 : dl-form) and dl-8-episerratinine (19 : dl-form).