Enantioselective β-Lactone Formation from Ketene and Aldehydes Catalyzed by a Chiral Oxazaborolidine
作者:Vijay Gnanadesikan、E. J. Corey
DOI:10.1021/ol061979h
日期:2006.10.1
[reaction: see text] A novel catalytic system has been developed for the enantioselective synthesis of beta-lactones from ketene and aldehydes.
[反应:见正文]已开发出一种新型催化体系,用于从烯酮和醛类对映体选择性合成β-内酯。
S<sub>N</sub>2 Ring Opening of β-Lactones: An Alternative to Catalytic Asymmetric Conjugate Additions
作者:Scott G. Nelson、Zhonghui Wan、Magdalena A. Stan
DOI:10.1021/jo025519n
日期:2002.7.1
Merging catalyticasymmetricacylhalide-aldehydecyclocondensation (AAC) reactions with ensuing Grignard-mediated ring opening of the derived enantiomerically enriched beta-lactones is presented as a generally useful asymmetric synthesis of beta-disubstituted carboxylic acids. Enantiomerically enriched beta-lactones are subject to efficient S(N)2 ring opening with a variety of copper-modified alkyl
Catalytic Asymmetric Synthesis of trans-Configured β-Lactones: Cooperation of Lewis Acid and Ion Pair Catalysis
作者:Thomas Kull、José Cabrera、René Peters
DOI:10.1002/chem.201000840
日期:——
development of the first trans‐selective catalytic asymmetric [2+2] cyclocondensation of acyl halides with aliphatic aldehydes furnishing 3,4‐disubstituted β‐lactones is described. This work made use of a new strategy within the context of asymmetric dual activation catalysis: it combines the concepts of Lewisacid and organic aprotic ionpaircatalysis in a single catalyst system. The methodology could
Practical Enantioselective Synthesis of β-Lactones Catalyzed by Aluminum Bissulfonamide Complexes
作者:Thomas Kull、René Peters
DOI:10.1002/adsc.200700084
日期:2007.7.2
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
Divergent reaction pathways in amine additions to β-lactone electrophiles. An application to β-peptide synthesis
作者:Scott G. Nelson、Keith L. Spencer、Wing S. Cheung、Steven J. Mamie
DOI:10.1016/s0040-4020(02)00722-6
日期:2002.8
β-Lactone electrophiles are subject to regioselective addition–elimination (AE) or SN2 ring opening with various nitrogen-based nucleophiles. Primary and secondary amines promote AE ring opening to deliver products that are the functional equivalent of amide aldol adducts. Azide and sulfonamide anion nucleophiles engender SN2 lactone ring opening to deliver N-protected β-amino acid derivatives. These
β-内酯亲电体会与多种基于氮的亲核体发生区域选择性加成-消除(AE)或S N 2开环。伯胺和仲胺可促进AE开环,从而提供功能上与酰胺醇醛加合物相同的产品。叠氮化物和磺酰胺阴离子亲核试剂使S N 2内酯开环传递N保护的β-氨基酸衍生物。这些依赖亲核试剂的开环途径,再加上通过酰基卤-醛环缩合反应获得的富含大量庚酮的β-内酯的便捷途径,构成了不对称有机合成的通用方法。还描述了该反应技术在基于从AAC开环序列中出现的旋光性β-叠氮酸的β肽合成新方法中的应用。