Rhodium Catalysts with a Chiral Cyclopentadienyl Ligand Derived from Natural R‐Myrtenal
Roman A. Pototskiy, Andrey V. Kolos, Yulia V. Nelyubina, Dmitry S. Perekalin
Abstract
A new chiral cyclopentadiene Cp myr H was synthesized from the natural terpene ( R )‐myrtenal in 5 steps and about 40 % total yield. The key step was the reaction of vinyl‐dibromocyclopropane derivative with MeLi which provided the diene Cp myr H via Skattebøl rearrangement. The reaction of Cp myr H with [(cod)Rh(OAc)] 2 gave the rhodium(I) complex (Cp myr )Rh(cod) and subsequent oxidation with halogens X 2 gave the rhodium(III) complexes [(Cp myr )RhX 2 ] 2 (X = Br, I). Complex (Cp myr )Rh(cod) in combination with benzoyl peroxide catalyzed the C–H activation of O ‐pivaloyl‐phenylhydroxamic acid and its subsequent annulation with alkenes giving dihydroisoquinolones with high yield (70–90 %) but moderate enantioselectivity (16–36 % ee ).