An acid catalysed ring rearrangement of a triflate derivative of D-mannono-?-lactone 6 is the key step in the synthesis of the C-glycosyl sugar amino acid derivatives 3 and 4, examples of carbohydrate amino acid building blocks with specific conformational preferences suitable for incorporation into combinatorial amide libraries; homo-oligomerisation via solution phase coupling procedures affords furanose carbopeptoids 1 which adopt novel solution state secondary structures.