Synthesis of Optically Active β,γ-Unsaturated α-Amino Acids and of α,β-Unsaturated γ-Amino Acids. SN2- vs. SN2’-Dichotomy of the Mitsunobu Amination of Allylic Alcohols
作者:Johann Mulzer、Günther Funk
DOI:10.1055/s-1995-3847
日期:1995.1
Novel and efficient syntheses (6-9 steps, overall yields 10-30%) are described for optically pure β,γ-unsaturated α-amino acids and α,β-unsaturated γ-amino acids, starting from (R)-isopropylidene glyceraldehyde and ethyl (S)-lactate, respectively. The key step is the Mitsunobu reaction of chiral secondary allylic alcohols with phthalimide as the nucleophile, where α,γ allylic transpositions are observed for the first time. The structure-α,γ-ratio-relationship is studied and also the stereochemistry of the allylic transposition. The α-substitution proceeds via clean SN2 inversion, whereas the γ-substitution corresponds to an (E)-anti attack of the nucleophilic with varying stereoselectivities.
Total synthesis of halipeptin A, a potent anti-inflammatory cyclodepsipeptide from a marine sponge
作者:Sousuke Hara、Kazuishi Makino、Yasumasa Hamada
DOI:10.1016/j.tetlet.2005.12.026
日期:2006.2
Totalsynthesis of halipeptin A, a potent anti-inflammatory cyclodepsipeptide, was achieved through proline-catalyzed asymmetric α-oxidation, diastereoselective aldol reaction, silver cyanide-mediated esterification, and macrolactamization.