A new protocol for the synthesis of a variety of N-containing aromatic heterocycles by a formal gold-catalyzed dehydro-Diels-Alder reaction of ynamide derivatives has been developed. Deuterium-labeling experiments and kinetic studies support the involvement of a dual gold catalysis mechanism in which a gold acetylide moiety adds onto an aurated keteneiminium.
Photosensitizers that gather high photo‐oxidizing power and strong visible‐light absorption are of great interest in the development of new photo‐chemotherapeutics. Indeed, such compounds constitute attractive candidates for the design of type I photosensitizers that are not dependent on the presence of oxygen. In this paper, we report on the synthesis and studies of new ruthenium(II) complexes that display strong visible‐light absorption and can oxidize guanine residues under visible‐light irradiation, as evidenced by nanosecond transient absorption spectroscopy. The reported compounds also tightly bind to G‐quadruplex DNA structures from the human telomeric sequence (TTAGGG repeat). The kinetic and thermodynamic parameters of the interaction of these Ru(II) complexes with G‐quadruplex and duplex DNA were studied thanks to luminescence titrations and bio‐layer interferometry measurements, which revealed higher affinities towards the non‐canonical G‐quadruplex architecture. Docking experiments and non‐covalent ionic analysis allowed us to gain information on the mode and the strength of the interaction of the compounds towards G‐quadruplex and duplex DNA. The different studies emphasize the substantial influence of the position and the number of non‐chelating nitrogen atoms on the interaction with both types of DNA secondary structures.
A new protocol for the synthesis of a variety of N‐containing aromatic heterocycles by a formal gold‐catalyzed dehydro‐Diels–Alder reaction of ynamide derivatives has been developed. Deuterium‐labeling experiments and kinetic studies support the involvement of a dual gold catalysis mechanism in which a gold acetylide moiety adds onto an aurated keteneiminium.
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