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DOI: 10.1055/s-0033-1340408
Synthesis of Pyrrolidinones via α,β-Unsaturated Acylammonium Ions
Direct Catalytic Asymmetric Synthesis of N-Heterocycles from Commodity Acid Chlorides by Employing α,β-Unsaturated Acylammonium Salts.
Angew. Chem. Int. Ed. 2013;
DOI: 10.1002/anie.201306050.
Publication History
Publication Date:
13 December 2013 (online)
![](https://www.thieme-connect.de/media/synfacts/201401/i_b121_s1_10-1055_s-0033-1340408.gif)
Significance
An asymmetric enantioselective Michael addition–proton transfer–lactamization or lactonization organocascade reaction is reported. The cinchona alkaloid derived catalysts 1 can generate chiral α,β-unsaturated acylammonium salts with crotonyl chlorides 2, giving pyrrolidinones, piperid-2-ones, and dihydropyridinones in good yields and high enantioselectivities.
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Comment
In the first step, the lithiated enolate is formed to participate in a conjugate addition to the acylammonium species, which derives from reaction of the chiral tertiary amine (R3 3N) with the acid chloride. After an intra- or intermolecular proton transfer, the acylammonium species undergoes intramolecular lactamization to regenerate the tertiary amine catalyst R3 3N. The products could be transformed into known precursors of various biologically active compounds.
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![](https://www.thieme-connect.de/media/synfacts/201401/i_b121_s1_10-1055_s-0033-1340408.gif)