71855-54-4Relevant 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.
