Asymmetric Total Synthesis of a Bioactive Lignanamide Using a 5‐endo‐tet‐type Cyclization of Activated Cyclopropylcarbinols and Synthetic Support for the Reaction Mechanism

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The first enantioselective whole synthesis of a bioactive lignanamide was reached with high enantiomeric excess. Essential artificial actions consist of an organocatalytic enantioselective cyclopropanation and a Lewis-acid-mediated chirality-transferring 5- endo-tet -sort cyclization that proceeds with a really high diploma of stereoinduction. The proposed system of the essential reaction is supported by the experimental results.   Based on these   experimental results, the  5-endo-tet -style cyclization of a cyclopropylcarbinol proceeds predominantly via an S N 1 mechanism with high  trans -selectivity, which arises from the steric hindrance of the neighboring substituent. Insignificant pathways incorporate the anchimeric participation of (i) the oxygen atom of the benzoyl team in an S N 2 mechanism and/or (ii) a benzene-coordinated transition condition in an S N 1-like mechanism.

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