Lasonolide A: Structural Revision and Total Synthesis
摘要:
The proposed structure of lasonolide A was synthesized employing radical cyclization reactions of beta-alkoxyacrylates for preparation of the tetrahydropyranyl units A and B, but the spectroscopic data did not match those of the natural product. Both enantiomers of a revised structure featuring 17E,25Z double bonds were synthesized, and the (-)-isomer was found to be the biologically active enantiomer.
Synthesis and evaluation of lasonolide A analogues
摘要:
Homolasonolide A and 10-desmethyllasonolide A are biologically less active than lasonolide A. The ethyl ester analogue of lasonolide A exhibited higher activity than the parent compound in some biological test. (C) 2004 Elsevier Ltd. All rights reserved.
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。
Synthesis of<i>anti</i>-1,3-Diols through RuCl<sub>3</sub>/PPh<sub>3</sub>-Mediated Hydrogenation of β-Hydroxy Ketones: An Alternative to Organoboron Reagents
Hydrogenation of enantioenriched β-hydroxyketones promoted by the catalyst generated in situ from commercially available and inexpensive RuCl3 and PPh3 under hydrogen pressure allowed the efficient preparation of a variety of anti-1,3-diols in good yields and with a high level of diastereoselectivity. This method should be an interesting alternative to organoboronreagents for the diastereoselective