Photocatalytic deoxygenative carboimination of unstrained γ,δ‐unsaturated oximes with π‐acceptors including trifluoromethyl alkenes, 1‐trifluoromethyl‐1,3‐butadienes, gem‐difluoroalkenes, acrylates, and styrenes has been achieved which provides an efficient and mild approach to construct structurally diverse and highly functionalized pyrrolines with good functional group tolerance. Importantly, upon utilization of trifluoromethyl alkenes as the coupling partners, the developed protocol not only allows the introduction of the extremely valuable gem‐difluoroalkene functionality and pyrroline moiety into one molecule, but could also further transform the resulting gem‐difluoroalkene‐functionalized pyrrolines to the architecturally intriguing indolizine alkaloids via oxidation/reduction and sequential C−F bond cleavage. The mechanistic studies indicated that a free‐radical and anionic process was probably involved in this photocatalytic deoxygenative transformation.
Single-atom catalysts (SACs), as atomically dispersed metal active sites anchored or coordinated on suitable supports, demonstrate large potential for use in therapeutic applications. SACs have structural features similar to those of natural enzyme, while exhibiting remarkable catalytic activity, desirable stability, and excellent selectivity. This systematic review aims to synthesize evidence on SACs’ biotherapy applications. Three databases (PubMed/MEDLINE, ISI Web of Science, and ScienceDirect) were searched to identify the studies that investigated the therapeutic efficacy of SACs. A total of 12 studies that fulfilled the inclusion criteria were included and reviewed, and the key findings were qualitatively synthesized. Overall, various SACs were investigated for biotherapy applications, including anticancer, anti-infection (antibacterial), and anti-inflammatory applications; brain trauma therapies, and oxidative-stress cytoprotection applications. All of the included studies showed that the synthesized SACs demonstrated superior therapeutic effects compared with their respective controls. Among the 12 studies reviewed, 11 studies showed satisfied biocompatibility of the applied SACs, whereas minimal cytotoxicity was reported in 1 study. Collectively, the reviewed studies indicated that SACs exhibited considerable promise in the field of biotherapy. Additional studies are needed for a better understanding of the effect of SACs in the treatment of various diseases.
In this work, we disclose two sets
of highly diastereo- and enantioselective
[3 + 2] cycloadditions of iminoesters with various α-substituted
acrylates, especially for sterically hindered and weakly activated
α-aryl or alkyl-substituted acrylates and alkenal, alkynal,
or unstable aliphatic aldehyde-derived iminoesters, catalyzed by the
AgHMDS/DTBM-Segphos or Ag2O/CA-AA-Amidphos catalytic system,
achieving the stereodivergent synthesis of chiral C4-ester-quaternary exo- or endo-pyrrolidines with high yields
and excellent diastereo- and enantioselectivities (up to >99:1
dr
and >99% ee). More importantly, the gram-scale synthetic exo-adduct displays significant applications in the aspect
of realizing
the total synthesis of the spirotryprostatin A alkaloid via nine steps
in a 36% overall yield.
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