Synthesis of 3-(trans-2'-Nitrocyclopropyl)alanine, a Constituent of the Natural Peptide-Lactone Hormaomycin
作者:Juergen Zindel、Armin de Meijere
DOI:10.1021/jo00115a009
日期:1995.5
The peptide-lactone hormaomycin 1a produced by Streptomyces griseoflavus contains two molecules of 3-(trans-2'-nitrocyclopropyl)alanine [Ala(3-Ncp)] (6). In order to determine the unknown absolute configurations of these unusual natural amino acid molecules, which supposedly are essential for the biological activity of 1a, enantiopure alcohols (trans-2-nitrocyclopropyl)methanol [(1S,2S)-13 and (1R,2R)-13] have been prepared in six steps from (R)- and (S)-2,3-O-isopropylideneglyceral-dehyde (17). The alcohols 13 were transformed to the bromides 23, and these in turn were coupled with suitable glycine equivalents like 2-[(diphenylmethylene)amino]acetates (24) to yield (2R/S,1'S,2'S)- and (2R/S,1'R,2'R)-3-(trans-2'-nitrocyclopropyl)alanines (6), after deprotection. The natural compound la contains one molecule each with (2R,1'R,2'R)- and (2S,1'R,2'R)-configuration, as established by comparison of the hydrolysate from natural la with the synthesized samples of (2R/S,1'R,2'R)-6 and (2R/S,1'S,2'S)-6.