Strain Promoted Click Chemistry of 2- or 8-Azidopurine and 5-Azidopyrimidine Nucleosides and 8-Azidoadenosine Triphosphate with Cyclooctynes. Application to Living Cell Fluorescent Imaging

Abstract

Strain-promoted click chemistry of nucleosides and nucleotides with an azido group directly attached to the purine and pyrimidine rings with various cyclooctynes in aqueous solution at ambient temperature resulted in efficient formation (3 min - 3 h) of fluorescent, light-up, triazole products. The 2- and 8-azidoadenine nucleosides reacted with fused cyclopropyl cyclooctyne, dibenzylcyclooctyne or monofluorocyclooctyne to produce click products functionalized with hydroxyl, amino, N-hydroxysuccinimide, or biotin moieties. The 5-azidouridine and 5-azido-2′-deoxyuridine were similarly converted to the analogous triazole products in quantitative yields in less than 5 minutes. The 8-azido-ATP quantitatively afforded the triazole product with fused cyclopropyl cyclooctyne in aqueous acetonitrile (3 h). The novel triazole adducts at the 2 or 8 position of adenine or 5-position of uracil rings induce fluorescence properties which were used for direct imaging in MCF-7 cancer cells without the need for traditional fluorogenic reporters. FLIM of the triazole click adducts demonstrated their potential utility for dynamic measuring and tracking of signaling events inside single living cancer cells.

Intercalation‐enhanced “Click” Crosslinking of DNA

“…Ac ell-permeable, small molecule containing complementary bioorthogonal functional groups is then added and reacts to generate DNA-DNAi nterstrand crosslinks.T ou tilize catalyst-free reactions, [11] azide groups were selected for incorporation into DNAd ue to their compatibility with strain-promoted azidealkyne click (SPAAC) reactions. [12] Forthe crosslinking agent, we envisioned that the integration of two strained alkynes directly into aplanar scaffold containing cationic substituents could furnish an ovel "bioorthogonal intercalating reagent" that reversibly intercalates into DNAa nd rapidly crosslinks azide groups in opposite strands of the duplex.…”

Synthesis of 8-(1,2,3-triazol-1-yl)-7-deazapurine nucleosides by azide–alkyne click reactions and direct C H bond functionalization

“…17,19 This is despite the fact that azidonucleosides 20–22 including 8-azido as well as 8-alkynyl purine23 nucleosides have been used as convenient substrates for CuAAC and strain-promoted azide-alkyne cycloaddition (SPAAC). 24–26 This approach is rapidly growing field with various applications, including in vivo imaging, of azido/alkyne-modified nucleoside/nucleotides 26–27 or DNA/RNA fragment click adducts. 28–33 …”

“…The resulting triazolyl products have "light-up" (inherited) fluorescent properties (Table 1), due to increased conjugation in the 7-deazapurine ring, and can therefore be used for fluorescent imaging in cancer cells, as recently reported with 8-triazolyl purine and 5-triazolyl pyrimidine nucleosides. 26–27 CuAAC reaction of 8-azido 3b with phenylacetylene in aqueous MeOH (4 days/r.t.) gave 8-(4-phenyl-1 H -1,2,3-triazol-1-yl)toyocamycin 9 (65%) after silica column purification.…”

Moderne Strategien zur Synthese funktioneller Fluorophore

“…DeRose und Mitarbeiter modifizierten das Chemotherapeutikum Picoplatin mithilfe einer Azidgruppe so, dass die Identifizierung und Abbildung seiner Oligonucleotid‐Bindungspartner nach Konjugation mit Alkin‐derivatisierten Dansylfluorophoren möglich wurde . Eine ähnliche Strategie wurde von Wnuk und Mitarbeitern verfolgt, die Nucleoside und Nucleotide mit Azidgruppen modifizierten und sie an gespannte Cyclooctine kuppelten, um eine direkte Bildgebung in MCF‐7‐Krebszellen zu ermöglichen . Die Nucleobasen‐Triazol‐Addukte erwiesen sich als geeignet für die Fluoreszenzlebensdauer‐Mikroskopie spezifischer Signalereignisse in lebenden Zellen.…”