Synthesis of glycosylamino acid containing dipeptides possessing a C-terminal α-ketoacid

CARB 40

Aditya K. Sanki, aksanki@yahoo.com, Rommel S. Talan, rtalan@UToledo.edu, Haojie Zheng, hzheng2@UToledo.edu, and Steven J. Sucheck, Steve.Sucheck@UToledo.edu. Department of Chemistry, University of Toledo, 2801 W. Bancroft Street, MS602, Toledo, OH 43606
α-Ketoacids are reported to undergo facile chemoselective decarboxylative condensation reactions with N-alkylhydroxylamines to form amides in aqueous solution. Conditions such as these are potentially useful in glycopeptide synthesis. Glycosylamino acid dipeptides containing C-terminal α-ketoacids have been prepared in order to explore this condensation chemistry. The dipeptides were prepared by coupling Nα-Fmoc-Thr(Ac3-α-D-GalNAc)-OH (1) with (cyanomethylene)phosphoranes 2, 3, and 4 to form dipeptide phosphoranes that were oxidized to the α-ketoacids Nα-Fmoc-Thr(Ac3-α-D-GalNAc)-Gly-CO2H (5), Nα-Fmoc-Thr(Ac3-α-D-GalNAc)-L-Ala-CO2H (6), and Nα-Fmoc-Thr(Ac3-α-D-GalNAc)-L-Val-CO2H (7), respectively. (Cyanomethylene)phosphoranes 2, 3, and 4 were prepared via the method of Wasserman starting from the corresponding Nα-Boc-protected amino acids.

 

General Posters
6:00 PM-8:00 PM, Tuesday, March 27, 2007 Hyatt Regency Chicago -- Riverside Center, Poster

Division of Carbohydrate Chemistry

The 233rd ACS National Meeting, Chicago, IL, March 25-29, 2007