Synthesis of α-Chiral Butyrolactones by Highly Stereoselective Radical Transfer or Sequential Asymmetric Alkylations: Concise Preparation of Leupyrrin Moieties.
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.
Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Gerhard-Domagk-Str. 1, 53121 Bonn (Germany).
Michael
M
Schrempp
Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Gerhard-Domagk-Str. 1, 53121 Bonn (Germany).
Sebastian
S
Thiede
Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Gerhard-Domagk-Str. 1, 53121 Bonn (Germany).
Daniel
D
Herkommer
Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Gerhard-Domagk-Str. 1, 53121 Bonn (Germany).
Andreas
A
Gansäuer
Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Gerhard-Domagk-Str. 1, 53121 Bonn (Germany). dirk.menche@uni-bonn.de.
Dirk
D
Menche
D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D000478:Alkylation; D002384:Catalysis; D003500:Cyclization; D007783:Lactones / Q000737:chemistry*; D013237:Stereoisomerism
D007783:Lactones; C481579:leupyrrin A1; C000607912:leupyrrin B1; D015107:4-Butyrolactone
butyrolactones; diastereoselectivity; leupyrrins; natural products; radicals