镍( II )催化的γ-烷基单取代的α,β-不饱和丁内酰胺与α,β-不饱和羰基化合物的不对称直接乙烯基Michael加成,以良好的收率和令人满意的对映选择性得到γ,γ-二烷基取代的丁内酰胺。基于该反应还开发了串联催化不对称插烯迈克尔加成/分子内迈克尔加成,这使得能够构建具有三个连续立体碳中心的对映体富集的八氢吲哚。
Aerobic Asymmetric Dehydrogenative Cross‐Coupling between Two CH Groups Catalyzed by a Chiral‐at‐Metal Rhodium Complex
作者:Yuqi Tan、Wei Yuan、Lei Gong、Eric Meggers
DOI:10.1002/anie.201506273
日期:2015.10.26
A sustainable CCbondformation is merged with the catalytic asymmetric generation of one or two stereocenters. The introduced catalytic asymmetric cross‐coupling of two CH groups with molecular oxygen as the oxidant profits from the oxidative robustness of a chiral‐at‐metal rhodium(III) catalyst and exploits an autoxidation mechanism or visible‐light photosensitized oxidation. In the latter case
Enantioselective Addition of Alkynyl Ketones to Nitroolefins Assisted by Brønsted Base/H‐Bonding Catalysis
作者:Teresa E. Campano、Igor Iriarte、Olatz Olaizola、Julen Etxabe、Antonia Mielgo、Iñaki Ganboa、José M. Odriozola、Jesús M. García、Mikel Oiarbide、Claudio Palomo
DOI:10.1002/chem.201805542
日期:2019.3.21
sets of enolizable alkynyl ketones (including methyl ynones with α‐aryl, α‐alkenyl, and α‐alkoxy groups) were able to react smoothly with nitroolefins with the assistance of bifunctional Brønsted base/H‐bond catalysts to provide adducts with two consecutive tertiary stereocenters in a highly diastereo‐ and enantioselective fashion. Further transformation of the obtained adducts into optically active acyclic
catalysts reported before were unsuccessful in this enantioselective radical C−N bond formation. The surprising preference for rhodium over iridium is attributed to much faster ligand‐exchange kinetics of the rhodium complexes involved in the catalytic cycle, which is crucial to keep pace with the highly reactive and thus short‐lived nitrogen‐centered radical intermediate.
Enantioselective Conjugate Addition of 2-Acylimidazoles with Nitroalkenes Promoted by Chiral-at-Metal Rhodium(III) Complexes
作者:Ganesh Kumar Thota、Gui-Jun Sun、Tao Deng、Yi Li、Qiang Kang
DOI:10.1002/adsc.201701377
日期:2018.3.20
An enantioselective conjugate addition of 2‐acylimidazoles with nitroalkenes catalyzed by chiral‐at‐metal rhodium(III) complex under mild reaction conditions was developed, affording versatile γ‐nitro ketone skeletons in good yields with excellent enantioselectivities (up to >99% ee).
functionalizations of more distal C-H bonds in hydrocinnamoyl ketones, Weinreb amides, and biphenyl Weinreb amides. Mechanistically, the coordination of these carbonyl groups and the bisdentate amino acid ligand with Pd(II) centers provides further evidence for our early hypothesis that the carbonyl groups of the potassium carboxylate are responsible for the directed C-H activation of carboxylicacids.