181649-52-5Relevant articles and documents
Synthesis of the octahydroindole unit of aeruginosins via asymmetric hydrogenation of the Diels-Alder adducts of 2-amido-2,4-pentadienoate
Hoshina, Yoichiro,Doi, Takayuki,Takahashi, Takashi
, p. 12740 - 12746 (2008/03/17)
An optically active octahydroindole, the core unit of aeruginosins (Choi) was synthesized. The Diels-Alder reaction of Danishefsky's diene with methyl (Z)-2-acetamido-2,4-pentadienoates provided the adducts regioselectively in good yield. The adducts were
First total syntheses of aeruginosin 298-A and aeruginosin 298-B, based on a stereocontrolled route to the new amino acid 6-hydroxyoctahydroindole-2-carboxylic acid
Valls, Nativitat,Lopez-Canet, Meritxell,Vallribera, Merce,Bonjoch, Josep
, p. 3446 - 3460 (2007/10/03)
The first total syntheses of aeruginosin 298-A (1) and aeruginosin 298-B (3) are described. The syntheses of the alternative putative structures 2 and 4 were also accomplished. The key common strategic element is the stereocontrolled synthesis of (2S,3aS,6R,7aS)-6-hydroxyoctahydroindole-2-carboxylic acid (L-Choi, 5) from L-tyrosine. The synthesis of this new bicyclic α-amino acid, which is the core of aeruginosins, involves Birch reduction of O-methyl-L-tyrosine (6) and aminocyclization of the resulting dihydroanisole 7 in acid medium, followed by N-benzylation to give the diastereoisomers 12 and 13. Upon acid treatment with HCl-MeOH, the last two produce an equilibrium mixture in which the endo isomer 13 significantly predominates. Hydrogenation of 13 in the presence of (Boc)2O gives 16, which on reduction with LS-Selectride furnishes the alcohol 22, a protected L-Choi. Successive couplings of 22 with D-leucine, protected (R)-(4-hydroxyphenyl)lactic acid, and L-arginine fragments, followed by reduction to the argininol level and a deprotection end step complete the synthetic sequence to produce aeruginosin 298-A (1). Spectral comparison showed that peptide 2, with the structure previously proposed for aeruginosin 298-A, was different from the natural product. However, synthetic 1 was found to be identical to the isolated natural sample of aeruginosin 298-A. These results unequivocally establish that the absolute stereochemistry of aeruginosin 298-A, formerly assigned incorrectly, is D-Hpla-D-Leu-L-Choi-L-Argol, as shown by structure 1. Aeruginosin 298-B was also synthesized and shown to be a mixture of rotamers of D-Hpla-D-Leu-L-ChoiNH2 (3), rather than an epimeric mixture of 3 and the L-Leu-incorporating 4.