The tetrabenzylglucosyloxycarbonyl(BGloc)-group-A carbohydrate-derived enzyme-labile urethane protecting group

The development of the tetrabenzylglucosyloxycarbonyl (BGloc)-protecting group as an enzymatically removable urethane protecting function for peptide synthesis is described. BGloc-protected amino acids are readily synthesized by conversion of amino acid allyl esters into the respective isocyanates, subsequent treatment with 2,3,4,6-tetrabenzylglucose and C-terminal allyl ester cleavage. From BGloc masked dipeptide esters, which are accessible by standard methods of peptide chemistry, the N-terminal urethane is selectively cleaved off in high yield via removal of the benzyl ethers by hydrogenation followed by hydrolysis of the urethane by means of α- and β-glucosidase under very mild reaction conditions.