Synthesis of α‐Chiral Butyrolactones by Highly Stereoselective Radical Transfer or Sequential Asymmetric Alkylations: Concise Preparation of Leupyrrin Moieties. Issue 45 (10th September 2015)

• Record Type: Journal Article
• Authors: Schrempp, Michael; Thiede, Sebastian; Herkommer, Daniel; Gansäuer, Andreas; Menche, Dirk
• Is Part Of: Chemistry. Volume 21:Issue 45(2015)
• Page Start: 16266
• Page End: 16271
• Publication Date: 2015-09-10
• Subjects: butyrolactones -- diastereoselectivity -- leupyrrins -- natural products -- radicals; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201502263
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: Inspired by the bioactive natural metabolites leupyrrin A1 and B1, 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. Abstract : A sequential, catalytic radical transfer enables a highly chemo‐, regio‐, and stereoselective synthesis of α‐chiral butyrolactones (see scheme; CP=Cyclopentadienyl). Alternatively, these heterocycles may be efficiently obtained by an asymmetric alkylation sequence, which enables a highly concise preparation of the authentic butyrolactone fragment of the leupyrrins, potent antifungal agents of myxobacterial origin.