Controlling the Course of Nucleophilic Additions to ortho‐Substituted (η6‐Anisole)tricarbonyl‐chromium Complexes: Dienol Ether Formation versus tele‐Substitution

Chlorotrimethylsilane is the reagent of choice to trap the ionic intermediate that arises on nucleophilic addition to ortho-substituted anisoletricarbonylchromium complexes and to suppress its tendency toward tele-substitution (relative to the methoxy group). Thus the planar-chiral complex 1 can be transformed into the cyclo-hexenone 2 with complete retention of the stereochemical information in greater than 95% ee. Compound 2 is a promising precursor for the total synthesis of (+)-ptilocaulin.