Total Synthesis of Macrosphelides A, B, and E: First Application of Ring-Closing Metathesis for Macrosphelide Synthesis
摘要:
A new synthetic route for macrosphelides A, B, and E based on ring-closing metathesis (RCM) was established. The substrates for RCM could be synthesized starting from commercially available chiral materials, methyl (S)-lactate and methyl (S)- or (R)-3-hydroxybutyrate, in good overall yields. In the investigation of the key RCM step, it was found that the steric factor around the reaction site significantly affected the reaction rate of macrocyclization. A detailed account regarding this synthetic study is described herein.
New Strategy for the Total Synthesis of Macrosphelides A and B Based on Ring-Closing Metathesis
作者:Yuji Matsuya、Takanori Kawaguchi、Hideo Nemoto
DOI:10.1021/ol0350689
日期:2003.8.1
[reaction: see text] A new total synthesis of macrosphelides A and B using ring-closingmetathesis (RCM) as a macrocyclization step is described. The substrate of the RCM could be synthesized from readily available chiral materials, methyl (S)-(+)-3-hydroxybutyrate and methyl (S)-(-)-lactate, with a high efficiency. The RCM proceeded in the presence of Grubbs' Ru-complex, providing a new effective synthetic
Highly concise syntheses of (+)-macrosphelides A and B were accomplished in this study. The key feature of our synthetic route involved the direct three-carbon homologation of the readily available Weinreb amide 6 by the addition of a trans-vinylogous ester anion equivalent and facile construction of the 16-membered macrolide skeleton of macrosphelides via an intramolecular nitrile oxide−olefin cycloaddition