Versatility of N-peptidyl and N-glycopeptidyl nitroindolines for the formation of peptide/glycopeptide acids, amides, and thioesters
N-acyl-7-nitroindolines are photoreactive compounds that are known to acylate a number of nucleophiles in inert aprotic solvents under neutral conditions when illuminated at 350 nm. We have assembled a MUC1-derived peptide and Tn or STn-containing MUC1 glycopeptides with a C-terminal photoreactive 7-nitroindoline linker attached to Sieber amide resin by solid phase peptide synthesis using the Fmoc strategy. This type of construction allows for the cleavage of fully protected photoreactive peptides/glycopeptides from the resin with dilute trifluoroacetic acid, or for the direct photorelease of protected peptide/glycopeptide derivatives. Here we demonstrate that N-peptidyl and N-glycopeptidyl 7-nitrindolines can be photochemically converted into their peptide acids, activated esters, amides, or thioesters when illuminated with near UV light in the presence of an appropriate nucleophile (H2O, HOBt, RNH2, or HOSu followed by RSH) thus demonstrating the chemical versatility of N-peptidyl-7-nitroindolines. ^
Barrera, Luis, "Versatility of N-peptidyl and N-glycopeptidyl nitroindolines for the formation of peptide/glycopeptide acids, amides, and thioesters" (2015). ETD Collection for University of Texas, El Paso. AAI10000795.