Lobocyclamide B from Lyngbya confervoides. Configuration and asymmetric synthesis of beta-hydroxy-alpha-amino acids by (-)-sparteine-mediated aldol addition.
[reaction: see text] Lobocyclamide B, a cyclododecapeptide containing five beta-hydroxy-alpha-amino acid residues, was isolated from Lyngbya confervoides. This is the first reported occurrence of gamma-hydroxythreonine in a natural peptide. Optically active beta-hydroxy-alpha-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.
MacMillan
John B
JB
Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616, USA.
Molinski
Tadeusz F
TF
D000596:Amino Acids / Q000737:chemistry*; D000935:Antifungal Agents / Q000737:chemistry* / Q000302:isolation & purification; D002851:Chromatography, High Pressure Liquid; D000458:Cyanobacteria / Q000737:chemistry*; D007202:Indicators and Reagents; D008094:Lithium / Q000737:chemistry; D008968:Molecular Conformation; D009904:Optical Rotation; D013034:Sparteine / Q000737:chemistry*
D000596:Amino Acids; D000935:Antifungal Agents; D007202:Indicators and Reagents; D013034:Sparteine; D008094:Lithium