Synthesis of coumarin or ferrocene labeled nucleosides via Staudinger ligation

BACKGROUND: Reaction of azides with triaryl phosphines under mild conditions gives iminophosphoranes which can react with almost any kind of electrophilic reagent, e.g. aldehydes/ketones to form imines or esters to form amides. This so-called Staudinger ligation has been employed in a wide range of applications as a general tool for bioconjugation including specific labeling of nucleic acids. RESULTS: A new approach for the preparation of labeled nucleosides via intermolecular Staudinger ligation is described. Reaction of azidonucleosides with triphenylphosphine lead to iminophosphorane intermediates, which react subsequently with derivatives of coumarin or ferrocene to form coumarin or ferrocene labeled nucleosides. Fluorescent properties of coumarin labeled nucleosides are determined. CONCLUSION: New coumarin and ferrocene labeled nucleosides were prepared via intermolecular Staudinger ligation. This reaction joins the fluorescent coumarin and biospecific nucleoside to the new molecule with promising fluorescent and electrochemical properties. The isolated yields of products depend on the structure of azidonucleoside and carboxylic acids. A detailed study of the kinetics of the Staudinger ligation with nucleoside substrates is in progress

Easy and effective method to produce functionalized particles for cellular uptake

In this contribution, a versatile approach for the synthesis of functionalized particles for drug delivery is presented, using two nonaggressive standardized procedures. The first procedure considered is the functionalization of an azido-terminated α-norbornenyl poly(ethylene oxide) (PEO) macromonomer with an alkyne-containing active molecule via the copper catalyzed azide alkyne cycloaddition, click type reaction. The functionalized macromonomer is then polymerized by Ring-Opening Metathesis Polymerization (ROMP) in dispersion to form functionalized particles. The second procedure consists in synthesizing particles by ROMP in dispersed media of norbornene with azido-terminated α-norbornenyl PEO macromonomer. The ROMP was initiated by the first generation Grubbs catalyst. Such functionalized core-shell particles have stealthy properties due to their PEO shell and can be viewed as universal nanocarriers on which any alkyne-modified active molecule can be grafted by click chemistry. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 201