Coloring Carbohydrates: Investigation of Azulene Derivatives as Blue Protecting Groups

Coloring carbohydrate derivatives by a chromophore tag greatly facilitates all purification steps during a synthetic sequence, according to a methodology called "chromophore- supported purification" (CSP). Herein an Fmoc-analogous blue protective group for CSP is introduced, based on guaiazulene. Following a mechanistic rational, the synthesis and introduction of this new protecting group is shown, together with its removal under variable conditions and its application for the synthesis of glycoclusters of a glycopeptide and glycopeptoid type.