An efficient and versatile approach for the preparation of a rhodamine B ester bioprobe library

A general approach for the preparation of a library consisting of reactive rhodamine B (RhB) bioprobes based on ester or thioester linkages is described. The synthesis of this library proceeds fast and efficiently in one reaction step. Pure RhB ester chromophores are readily obtained directly from the reaction mixture following a simple and straight forward workup procedure without further HPLC purification required. A variety of functional groups are attached to the RhB scaffold yielding the functional chromophores in moderate to high yields with particular focus on introducing bioorthogonal substituents suitable for protein and peptide labeling. The approach reported herein provides a concise and practical route to access a variety of reactive RhB fluorophores that could be applied for various bioconjugation chemistries. (C) 2012 Elsevier Ltd. All rights reserved.