122092-89-1Relevant articles and documents
3-Triphenylphosphonio-2,5-piperazinediones as new chiral glycine cation equivalents
Gorewoda, Tadeusz,Mazurkiewicz, Roman,Simka, Wojciech,Mloston, Grzegorz,Schroeder, Grzegorz,Kubicki, MacIej,Kuznik, Nikodem
experimental part, p. 823 - 833 (2011/09/12)
3-Triphenylphosphonio-2,5-piperazinediones were effectively synthesized from homochiral valine or proline via Boc-Val-Gly-OMe, Boc-Pro-Gly-OMe or Cbz-Pro-Gly-OMe. Retention of configuration of the primary stereogenic center of the valine and proline moieties was observed. Diastereoselective nucleophilic substitution of the triphenylphosphonium group in 2,5-piperazinediones with S-, N-, P- and C-nucleophiles was observed. The configuration of the substitution products was assigned either by their hydrolysis and decarboxylation or based on the analysis of the H-C(3)-N-H coupling constants of 3-substituted-2,5- piperazinediones derived from proline. The trans-stereoselectivity was predominant in reactions of 3-triphenylphosphonio-1,6-trimethylene-2,5- piperazinediones with the nucleophiles investigated. The stereodifferentiating ability of the proline moiety is much stronger than that of the valine unit and allowed nucleophilic α-functionalization of the glycine moiety with good to excellent diastereoselectivity.
ANODIC OXIDATION OF N-ACYL AND N-ALKOXYCARBONYL DIPEPTIDE ESTERS AS A KEY STEP FOR THE FORMATION OF CHIRAL HETEROCYCLIC SYNTHETIC BUILDING BLOCKS
Papadopoulos, Apostolos,Lewall, Burhansha,Steckhan, Eberhard,Ginzel, Klaus-Dieter,Knoch, Falk,Nieger, Martin
, p. 563 - 572 (2007/10/02)
The anodic oxidation of N-protected dipeptide esters using chloride as a redox catalyst can be performed regioselectively at the C-terminal amino acid.With methanol as solvent, glycine as the C-terminal, and L-valine or L-proline as N-terminal amino acid methoxylation at the glycine residue takes place.Deprotection of this product leads to the (3S,6RS)-6-methoxy-2,5-piperazinedione (3) which can be applied as a chiral cationic glycine equivalent.The exchange of the methoxy group by C-nucleophiles takes place with high trans-diastereoselectivity under steric control by the substituent in 3-position.With branched amino acids at the C-terminus of the dipeptide ester the anodic oxidation in acetonitrile/methanol (95:5) as solvent with tetraethylammonium chloride as supporting electrolyte and redox catalyst leads to methyl imidazolidin-4-one-2-carboxylates.The cyclization takes place via the intermediate formation of the N-acylimino ester of the C-terminal amino acid.
