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Practical Enantioselective Synthesis of β‐Lactones Catalyzed by Aluminum Bissulfonamide Complexes
Author(s) -
Kull Thomas,
Peters René
Publication year - 2007
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.200700084
Subject(s) - enantioselective synthesis , chemistry , ligand (biochemistry) , ketene , catalysis , bromide , combinatorial chemistry , cycloaddition , organic chemistry , biochemistry , receptor
The development of an efficient and practical aluminum‐bissulfonamide complex catalyzed enantioselective formation of β‐lactones by [2+2] cycloaddition of ketene (generated in situ from acetyl bromide by dehydrobromination) with various α‐unbranched and ‐branched aliphatic aldehydes is presented. The methodology offers the advantage of operational simplicity not only as the ligand synthesis requires just a single sulfonylation step from commercially available enantiomerically pure diamines. The products are formed in high to excellent yields with ee values typically ranging from 78 to 90 % using 10 mol % of the bissulfonamide ligand. The key finding of this work was a remarkable rate acceleration by using an aluminum/ligand ratio of 1.5:1.