Publication Date:
2012-11-20
Description:
The enantioselective condensing reagent 4,6-dimethoxy-1,3,5-triazine (DMT)/strychnine/BF was obtained by treatment of 2-chloro-4,6-dimethoxy-1,3,5-triazine (CDMT) with strychnine tetrafluoroborate. The reagent was useful under typical conditions of solid-phase peptide synthesis (SPPS) with enantiomerically homogeneous substrates. By SPPS, desired dipeptides were obtained in 84–94% yield using 4 equiv. of racemic Fmoc-Ala, Fmoc-Phe, and/or Fmoc-Tyr for 1 equiv. of Wang resin loaded with Gly, Ala, Leu, Phe, Glu( t Bu), and/or Pro, respectively. For all three Fmoc-protected amino acids, the configuration of the enantiomer preferred under SPPS conditions was independent of the structure of the acylated component and identical to that established in condensations proceeding in solution. In all cases, the enantiomer ratios L / D (er) were in a similar range, and varied from 9 : 92 to 2 : 98 for alanine, and from 90 : 10 to 100 : 0 for aromatic amino acids. The synthesis of Ac- L -Lys(Ac)- D -Ala- D -Ala-OH from racemic Fmoc-Ala gave an L / D ratio of 10 : 90 for the esterification of Wang resin, and 0 : 100 for the formation of peptide bonds.
Print ISSN:
0018-019X
Electronic ISSN:
1522-2675
Topics:
Chemistry and Pharmacology
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