Lobocyclamide B from Lyngbya confervoides. Configuration and Asymmetric Synthesis of β-Hydroxy-α-amino Acids by (−)-Sparteine-Mediated Aldol Addition

John B. MacMillan and Tadeusz F. Molinski*
Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616
Org. Lett., 2002, 4 (11), pp 1883–1886
DOI: 10.1021/ol025876k
Publication Date (Web): April 30, 2002
Copyright © 2002 American Chemical Society
*

In papers with more than one author, the asterisk indicates the name of the author to whom inquiries about the paper should be addressed.

, tfmolinski@ucdavis.edu

Abstract

Abstract Image

Lobocyclamide B, a cyclododecapeptide containing five β-hydroxy-α-amino acid residues, was isolated from Lyngbya confervoides. This is the first reported occurrence of γ-hydroxythreonine in a natural peptide. Optically active β-hydroxy-α-amino acids required for configurational analysis of the title compound were prepared using a novel (−)-sparteine-mediated asymmetric aldol addition of N-(diphenylmethylene)glycine tert-butyl ester to aldehydes. The method is general for aliphatic and aryl aldehydes and notable for operational simplicity.

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History

  • Published In Issue May 30, 2002
  • Received March 14, 2002

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