Contribution to the synthesis of aureobasidin A. Synthesis of cyclopeptolides containing the sequence leucyl-N-methyl-beta-hydroxyvalyl-(2R)-oxy-(3R)-methyl-pentanoi c acid.
The efficient antimycotic agent aureobasidin A, isolated from the culture broth of Aureobasidium pullulans R 106, and the [(R)-Pro9]-aureobasidin A were prepared starting from benzyl N-Boc-N-methyl-(S)-beta-triethylsiloxyvalinate, the synthesis of which is described here. The easy accessibility of the tripeptolide benzyl Boc-leucyl-N-methyl-beta-hydroxyvalyl-(2R)-oxy-(3R)-methylpentanoa te [Boc-Leu-HOMeVal-(R)-HMP-OBn] facilitates the construction of the cyclopeptolides 28, 34, 45 and 47. The peptide bonds of the N-methylamino acids were formed with the help of O-(7-azabenzotriazol-1-yl)-1,1,3,3-tetramethyluronium hexafluorophophate. The rings of [(R)-Pro9]-aureobasidin A and of cyclopeptolides 28, 34, 45 and 47 were closed by way of pentafluorophenyl esters. The ring of aureobasidin A could only be formed with bromo-tris-pyrrolidinophosphonium hexafluorophosphate.
Schmidt
U
U
Institute of Organic Chemistry, University of Stuttgart, Germany. ioc@po.uni-stuttgart.de
Schumacher
A
A
Mittendorf
J
J
Riedl
B
B
D001671:Biochemistry / Q000379:methods*; D047630:Depsipeptides; D010456:Peptides, Cyclic / Q000138:chemical synthesis*
D047630:Depsipeptides; D010456:Peptides, Cyclic; C071398:aureobasidin A