enantioselective Negishi cross‐coupling reaction, and the first arylation of α‐halo esters with arylzinc halides, are disclosed. Employing a cobalt‐bisoxazoline catalyst, various α‐arylalkanoic esters were synthesized in excellent enantioselectivities and yields (up to 97 % ee and 98 % yield). A diverse range of functional groups, including ether, halide, thioether, silyl, amine, ester, acetal, amide, olefin
is one of the most attractive catalysts, especially for aromatic C–H functionalizations. However, stoichiometric amounts of oxidants and strong carbanions are required, and C–H tertiary alkylation, especially with electron-deficient alkylgroups, is unexplored. In this paper, we describe the development of iron-catalyzed selective C–H tertiary alkylations with heteroaromatics, in which an iron salt
Dichloromethane as a Chlorination Reagent for α-Bromocarbonyl Compounds in the Presence of a Copper Catalyst
作者:Kentaro Takeuchi、Syo Ishida、Takashi Nishikata
DOI:10.1246/cl.170062
日期:2017.5.5
We found that dichloromethane is a powerful chlorinatingreagent for the congested 3° and 2° Csp3–Br bond of α-bromocarbonyl amides, esters, and ketones. In the presence of an appropriate copper complex as a catalyst, the desired chlorination occurred within an hour. Control experiments revealed that in situ-generated CuCl2 is a key chlorinating agent that reacts with the 3° or 2° alkyl radicals generated
Oxidative cyclization of 2-allenyl-1,1′-biphenyls with α-carbonyl alkyl bromides: facile access to functionalized phenanthrenes
作者:Cheng-Yong Wang、Gao-Hui Pan、Fan Chen、Jin-Heng Li
DOI:10.1039/c7cc00483d
日期:——
A new copper-facilitated oxidative cyclization of 2-allenyl-1,1′-biphenyls with α-carbonyl alkyl bromides for producing functionalized phenanthrenes is presented, which represents the first allene 2,3-dicarbofunctionalization triggered by oxidative radical-medicated C3-addition of the terminal allene moiety and C–Br/C–H functionalization.
cobalt-bisoxazoline catalyst and afforded various α-alkyl-β,γ-unsaturated esters with excellent enantioselectivities and moderate to good yields (≤95% ee and ≤82% yields). The formal synthesis of the Californiaredscalepheromone using this method was investigated, and radical clock experiments were performed.