SmI2-mediated reductive cleavage of α-hetero substituents of α-alkyl or α-aryl ketones and lactone gave the corresponding “thermodynamic samarium enolates”. Enantioselective protonation of the samarium enolates with C2-symmetric chiral diols afforded the corresponding ketones and lactone in moderate to high enantioselectivities.
Distal-Selective Hydroformylation using Scaffolding Catalysis
作者:Candice L. Joe、Thomas P. Blaisdell、Allison F. Geoghan、Kian L. Tan
DOI:10.1021/ja504247g
日期:2014.6.18
In hydroformylation, phosphorus-based directinggroups have been consistently successful at placing the aldehyde on the carbon proximal to the directinggroup. The design and synthesis of a novel catalyticdirectinggroup are reported that promotes aldehyde formation on the carbon distal relative to the directing functionality. This scaffolding ligand, which operates through a reversible covalent bond
Enantioselective α-Arylation of Carbonyls via Cu(I)-Bisoxazoline Catalysis
作者:James S. Harvey、Scott P. Simonovich、Christopher R. Jamison、David W. C. MacMillan
DOI:10.1021/ja206050b
日期:2011.9.7
The enantioselective alpha-arylation of both lactones and acyl oxazolidones has been accomplished using a combination of diaryliodonium salts and copper catalysis. These mild catalytic conditions provide a new strategy for the enantioselective construction and retention of enolizable alpha-carbonyl benzylic stereocenters, a valuable synthon for the production of medicinal agents.
Accessing non-natural reactivity by irradiating nicotinamide-dependent enzymes with light
作者:Megan A. Emmanuel、Norman R. Greenberg、Daniel G. Oblinsky、Todd K. Hyster
DOI:10.1038/nature20569
日期:2016.12.15
nicotinamide co-factors (molecules that assist enzyme-mediated catalysis). Under irradiation with visible light, the nicotinamide-dependent enzyme known as ketoreductase can be transformed from a carbonyl reductase into an initiator of radical species and a chiral source of hydrogen atoms. We demonstrate this new reactivity through a highly enantioselective radical dehalogenation of lactones—a challenging transformation