N-(ethoxycarbonyl)ferrocenecarboxamide: Synthesis and use as the pronucleophile in the Mitsunobu reaction

The title compound has been synthesized in the reaction of ferrocene with ethoxycarbonyl isocyanate in methanesulfonic acid. It has been found that it undergoes N-alkylation with benzyl alcohols under classical Mitsunobu conditions (PPh3/DEAD). However, in the reaction with cholesterol and stigmasterol O-alkylation with inversion of configuration occurred (confirmed by hydrolysis of the product obtained from cholesterol to epicholesterol). The structure of the product obtained from p-nitrobenzyl alcohol was determined by X-ray diffraction.