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Synthesis of α‐Chiral Butyrolactones by Highly Stereoselective Radical Transfer or Sequential Asymmetric Alkylations: Concise Preparation of Leupyrrin Moieties
Author(s) -
Schrempp Michael,
Thiede Sebastian,
Herkommer Daniel,
Gansäuer Andreas,
Menche Dirk
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201502263
Subject(s) - stereoselectivity , chemistry , combinatorial chemistry , stereochemistry , chiral auxiliary , enantioselective synthesis , catalysis , organic chemistry
Inspired by the bioactive natural metabolites leupyrrin A 1 and B 1 , two novel stereoselective methods for the highly concise synthesis of densely substituted α‐chiral butyrolactones are reported. The first approach relies on an innovative three‐step Ti III ‐catalyzed radical reaction that proceeds with excellent chemo‐, regio‐, and stereoselectivity. The alternative route utilizes sequential asymmetric alkylations and enables asymmetric synthesis of the authentic α‐tetrasubstituted butyrolactone motif of the leupyrrins in only four steps from commercially available substrates.