Radical–radical coupling, the selective reaction between two different radical species, has contributed to the methodology for connecting bulky units. Light-driven N-heterocyclic carbene (NHC) organocatalysis is recognized as a state-of-the-art methodology enabling radical–radical coupling. The catalytic process involves forming an acyl azolium intermediate from the NHC catalyst and an acyl donor, followed by single electron reduction of this key intermediate, which is largely dependent on the photoredox catalyst. We designed a radical NHC catalysis in which the direct photoexcitation of a borate to form a high reducing agent facilitated the single electron reduction event. The borate produces an alkyl radical for the single electron transfer process to accomplish the radical–radical coupling. This protocol enables cross-coupling between alkylborates and acyl imidazoles in addition to radical relay-type alkylacylations of alkenes with alkylborates and acyl imidazoles, affording ketones with a broad scope.
Unveiling biomedical functions of tumor‐resident microbiota is challenging for developing advanced anticancer medicines. This study demonstrates that isolated intratumoral bacteria, associated with natural purple photosynthetic bacteria, have inherent biocompatibility and strong immunogenic anticancer efficacies. They preferentially grow and proliferate within a targeted tumor milieu, which effectively causes immune cells to infiltrate the tumor and provoke strong anticancer responses in various syngeneic mouse models, including colorectal cancer, sarcoma, metastatic lung cancer, and extensive drug‐resistant breast cancer. Furthermore, these functional bacteria‐treated mice exhibit excellent anticancerous responses and have significantly prolonged survival rates with effective immunological memory. Light‐harvesting nanocomplexes of microbial consortia of intratumoral bacteria and purple photosynthetic bacteria can diagnose tumors using bio‐optical‐window near‐infrared light, making them useful theranostic agents for highly targeted immunological elimination of the tumor and for precisely marking tumor location.
Unveiling the different biomedical functions of tumor-resident microbiota has remained challenging for the development of advanced anticancer medicines. Here we show that isolated intratumoral bacteria with its association with natural purple photosynthetic bacteria have a high innate biocompatibility and drastic immunogenic anticancer efficacies. They preferentially grow and proliferate within targeted tumor milieu, which effectively causes immune cells to infiltrate the tumor and provoke strong anticancer responses in various syngeneic mouse models including those of colorectal cancer, sarcoma, metastatic lung cancer, and extensive drug-resistant breast cancer. Furthermore, these functional bacteria-treated mice, that exhibit excellent anticancerous responses of tumors, have significantly prolonged survival rates with effective immunological memory. Notably, light-harvesting nanocomplexes of microbial consortium of intratumoral bacteria and purple photosynthetic bacteria is capable of tumor diagnosis using bio-optical-window near-infrared light, making them useful theranostic agents for highly targeted immunological elimination of the tumor and for precisely marking tumor location.
meta-Selective functionalisation of electron-rich arenes provides a non-traditional route to organic synthesis. In classical electrophilic aromatic substitution of electron-donating group-pendant arenes, functionalisation occurs according to ortho- and para-orientation. There have been numerous efforts to overcome this selectivity, and various synthetic methods have been developed, mainly based on transition metal catalysis. Here, we show a new N-heterocyclic carbene and organic photoredox cocatalysis for meta-selective acylation of electron-rich arenes. This approach proceeds without the directing groups or steric factors required in transition metal catalysis, resulting in precisely opposite regioselectivity from conventional approaches such as the Friedel–Crafts acylation. The catalytic system involves a sequence of single electron oxidation of an electron-rich arene followed by the radical–radical coupling between a ketyl radical and an arene radical cation. This protocol will lead to the expeditious synthesis of organic molecules that commonly require multiple steps and rare metals and promotes the construction of libraries of biologically active molecules.
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