Organocatalytic Double Michael Reaction of 7‐Oxohept‐2‐enoates and Nitrostyrene – Formal Synthesis of (–)‐α‐ and (–)‐β‐Lycorane

Abstract

Abstract Organocatalytic conjugate addition of 7‐oxohept‐2‐enoate to nitrostyrene provided an ω‐nitro‐α,β‐unsaturated ester. Subsequent intramolecular cyclization afforded the highly functionalized cyclohexane carboester with four stereogenic centers with high diastereoselectivity and high enantioselectivity (>99 % ee ). Some adducts were transformed into the intermediates of the synthesis of (–)‐α‐ and (–)‐β‐lycorane. Application of the reactions to the corresponding dialdehyde provided bicyclo[2.2.2]octanes.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)