Synthesis of Modyfied Fluoresceine for Click Reactions

Abstract

Reactions of azide-alkilic cycloaddition are well known since 1893. At the same time, with the elaboration of click chemistry, the techniques of labelling biological objects, particularly by fluorescent dyes, were widely developed. The use of fluorescent labels provides the ability to visually monitor the process streamlines hardware load and reduces research time. Fluorescein is among the fluorophores mostly used for labelling of biomolecules due to its high quantum yields and good stability in biological media. However, despite of commercial availability of fluorescein derivatives functionalized for use in click reactions, methods for their synthesis are virtually absent in the literature. Therefore, we have developed a reliable and effective methodic for the synthesis of functionalized fluoresceines for the use in the click reactions. Synthesis of diacetyl N-(4-azidobutyl)-fluoresceine-5(6)-carboxamide was performed in six stages, starting form resorcinol and trimellitic acid anhydride. The diacetylated analogue was synthesized for the click modifications in the “soft” conditions, since N-(4-azidobutyl)-fluorescein-5(6)-carboxamide is poorly soluble in the classic organic solvents. Proposed synthetic protocol allows to increase the yield of the final and intermediate compounds and to optimized the procedure of their isolation and purification.

Esterification vs. 1,3-Dipolar Cycloaddition Synthetic Approaches for Preparation of the Fluorescently Labelled Iron(II) Clathrochelates

“…For this purpose, we used the earlier described [20] propargylamine iron(II) clathrochelate complex with a terminal reactive C≡C bond as the reactive macrobicyclic precursor for its further functionalization using the well-known copper-promoted "click" reactions. [21][22][23][24][25][26][27][28] Indeed, the coumarin-terminated iron(II) cage complex was obtained by 1,3-dipolar cycload-Fluorescently Labelled Iron(II) Clathrochelates dition using the corresponding one-pot copper-promoted "click"-reaction shown in Scheme 5.…”

Synthesis and spectral characterization of the first fluorescein-tagged iron(ii) clathrochelates, their supramolecular interactions with globular proteins, and cellular uptake

“… 21 Diacetyl N -(4-azobutyl)-fluorescein-5(6)-carboxamide was obtained using a known synthetic procedure. 22 Bovine Serum Albumin (BSA) and human serum albumin (HAS) were obtained commercially (SAF® and Fisher Bioreagents, respectively). β -Lactoglobulin (BLG), lysozyme (LYZ), human insulin, trypsin, and analytical grade DMSO were also purchased from SAF®.…”