Fluorescent 5-Pyrimidine and 8-Purine Nucleosides Modified with an N-Unsubstituted 1,2,3-Triazol-4-yl Moiety

The Cu(I)- or Ag(I)-catalyzed cycloaddition between 8-ethynyladenine or guanine nucleosides and TMSN₃ gave 8-(1- H-1,2,3-triazol-4-yl) nucleosides in good yields. On the other hand, reactions of 5-ethynyluracil or cytosine nucleosides with TMSN₃ led to the chemoselective formation of triazoles via Cu(I)-catalyzed cycloaddition or vinyl azides via Ag(I)-catalyzed hydroazidation. These nucleosides with a minimalistic triazolyl modification showed excellent fluorescent properties with 8-(1- H-1,2,3-triazol-4-yl)-2'-deoxyadenosine (8-TrzdA), exhibiting a quantum yield of 44%. The 8-TrzdA 5'-triphosphate was incorporated into duplex DNA containing a one-nucleotide gap by DNA polymerase β.

Trifluoroethoxy-Coated Subphthalocyanine affects Trifluoromethylation of Alkenes and Alkynes even under Low-Energy Red-Light Irradiation

Photoredox chemical reactions induced by visible light have undergone a renaissance in recent years. Polypyridyl dyes such as Ir(ppy)3 and Ru(bpy)3 are key catalysts in this event, and blue- or white-light irradiation is required for the chemical transformations. However, it remains a challenge to achieve reactions under the lower energy of red light. We disclose, herein, that trifluoroethoxy-coated subphthalocyanine realizes the red-light-driven trifluoromethylation of alkenes and alkynes with trifluoromethyl iodide in good-to-high yields. Perfluoroalkylations were also achieved under red light. The reaction mechanism is discussed with the support of UV/Vis spectroscopy and cyclic voltammetry of trifluoroethoxy-coated subphthalocyanine. Light irradiation/dark study also supports the proposed mechanism.

Synthesis of Phthalocyanines with a Pentafluorosulfanyl Substituent at Peripheral Positions

The pentafluorosulfanyl (SF5) group is more electronegative, lipophilic and sterically bulky relative to the well-explored trifluoromethyl (CF3) group. As such, the SF5 group could offer access to pharmaceuticals, agrochemicals and optoelectronic materials with novel properties. Here, the first synthesis of phthalocyanines (Pcs), a class of compounds used as dyes and with potential as photodynamic therapeutics, with a SF5 group directly attached on their peripheral positions is disclosed. The key for this work is the preparation of a series of SF5-containing phthalonitriles, which was beautifully regio-controlled by a stepwise cyanation via ortho-lithiation/iodination from commercially available pentafluorosulfanyl arenes. The macrocyclization of the SF5-containing phthalonitriles to SF5-substituted Pcs required harsh conditions with the exception of the synthesis of β-SF5-substituted Pc. The regiospecificity of the newly developed SF5-substituted Pcs observed by UV/Vis spectra and fluorescence quantum yields depend on the peripheral positon of the SF5 group.