排序方式: 共有63条查询结果,搜索用时 15 毫秒
61.
Carla Calvó-Tusell Dr. Zhen Liu Dr. Kai Chen Prof. Dr. Frances H. Arnold Dr. Marc Garcia-Borràs 《Angewandte Chemie (International ed. in English)》2023,62(35):e202303879
We report a computationally driven approach to access enantiodivergent enzymatic carbene N−H insertions catalyzed by P411 enzymes. Computational modeling was employed to rationally guide engineering efforts to control the accessible conformations of a key lactone-carbene (LAC) intermediate in the enzyme active site by installing a new H-bond anchoring point. This H-bonding interaction controls the relative orientation of the reactive carbene intermediate, orienting it for an enantioselective N-nucleophilic attack by the amine substrate. By combining MD simulations and site-saturation mutagenesis and screening targeted to only two key residues, we were able to reverse the stereoselectivity of previously engineered S-selective P411 enzymes. The resulting variant, L5_FL-B3 , accepts a broad scope of amine substrates for N−H insertion with excellent yields (up to >99 %), high efficiency (up to 12 300 TTN), and good enantiocontrol (up to 7 : 93 er). 相似文献
62.
Fei Cong Riccardo S. Mega Jinhong Chen Craig S. Day Prof. Ruben Martin 《Angewandte Chemie (International ed. in English)》2023,62(15):e202214633
Herein, we report a Cu-mediated trifluoromethylation of carbonyl-type compounds and unactivated olefins enabled by visible-light irradiation via σ C(sp3)−C bond-functionalization. The reaction is distinguished by its modularity, mild conditions and wide scope—even in the context of late-stage functionalization—thus offering a complementary approach en route to valuable C(sp3)−CF3 architectures from easily accessible precursors. 相似文献
63.
Prof. Dr. Max M. Hansmann 《Angewandte Chemie (International ed. in English)》2023,62(35):e202304574
Over decades diazoalkenes (R2C=C=N2) were postulated as reactive intermediates in organic chemistry even though their direct spectroscopic detection proved very challenging. In the 1970/80ies several groups probed their existence mainly indirectly by trapping experiments or directly by matrix-isolation studies. In 2021, our group and the Severin group reported independently the synthesis and characterization of the first room-temperature stable diazoalkenes, which initiated a rapidly expanding research field. Up to now four different classes of N-heterocyclic substituted room-temperature stable diazoalkenes have been reported. Their properties and unique reactivity, such as N2/CO exchange or utilization as vinylidene precursors in organic and transition metal chemistry are presented. This review summarizes the early discoveries of diazoalkenes from their initial postulation as transient, elusive species up to the recent findings of the room-temperature stable derivatives. 相似文献