Unveiling Latent Photoreactivity of Imines.

Unlike carbonyl compounds, it has long been common understanding that excited imines show virtually no photoreactivity, and hence their properties and potential utility in chemical science remain largely unexplored. Now, a strategy is presented for eliciting latent photoreactivity of imines based on the introduction of a donor-acceptor (D-A) structure to extend the lifetime of their photoexcited states. A series of spectroscopic analyses and density functional theory calculations reveal unique photophysical properties of the D-A-type imines. Furthermore, the reactivity of the D-A-type imines is demonstrated by using them as a photoredox catalyst for atom-transfer radical addition. These findings illuminate a previously neglected chemical space in the field of photochemistry, which will be exploited by taking advantage of the inherent structural modularity of imines.

Recovery of cell nuclei from 15,000 years old mammoth tissues and its injection into mouse enucleated matured oocytes.

Here, we report the recovery of cell nuclei from 14,000-15,000 years old mammoth tissues and the injection of those nuclei into mouse enucleated matured oocytes by somatic cell nuclear transfer (SCNT). From both skin and muscle tissues, cell nucleus-like structures were successfully recovered. Those nuclei were then injected into enucleated oocytes and more than half of the oocytes were able to survive. Injected nuclei were not taken apart and remained its nuclear structure. Those oocytes did not show disappearance of nuclear membrane or premature chromosome condensation (PCC) at 1 hour after injection and did not form pronuclear-like structures at 7 hours after injection. As half of the oocytes injected with nuclei derived from frozen-thawed mouse bone marrow cells were able to form pronuclear-like structures, it might be possible to promote the cell cycle of nuclei from ancient animal tissues by suitable pre-treatment in SCNT. This is the first report of SCNT with nuclei derived from mammoth tissues.

Photoredox ketone catalysis for the direct C-H imidation and acyloxylation of arenes.

The photoexcited aryl ketone-catalyzed C-H imidation of arenes and heteroarenes is reported. Using 3,6-dimethoxy-9H-thioxanthen-9-one as a catalyst in combination with a bench-stable imidating reagent, C-N bond formation proceeds with high efficiency and a broad substrate scope. A key part of this method is that the thioxanthone catalyst acts as an excited-state reductant, thus establishing an oxidative quenching cycle for radical aromatic substitution. The synthetic potential of this photoexcited ketone catalysis is further demonstrated by application to the direct C-H acyloxylation of arenes.