229184-96-7Relevant academic research and scientific papers
Catalytic Desymmetric Cycloaddition of Diaziridines with Metalloenolcarbenes: The Role of Donor–Acceptor Cyclopropenes
Zheng, Haifeng,Doyle, Michael P.
, p. 12502 - 12506 (2019)
A chiral copper(I) complex catalyzes reactions of symmetric diaziridines with enol diazo compounds, which react through N?N bond ring opening in a formal [3+3] cycloaddition to form four chiral centers with high stereocontrol. A broad spectrum of bridged dinitrogen heterocycles were obtained in high yields and excellent diastereo- and enantioselectivities from γ-substituted enol diazoacetates, while their geometrical isomers gave different enantioselectivities. Donor–acceptor cyclopropenes formed from the geometrical isomers of the γ-substituted enol diazoacetates underwent catalytic ring opening to give only the Z isomer of the metalloenolcarbene intermediate, provided excellent yields and selectivities for the 1,5-diazabicyclo[n.3.1]non-2-ene derivatives.
Catalytic Asymmetric Fluorination of Copper Carbene Complexes: Preparative Advances and a Mechanistic Rationale
Buchsteiner, Michael,Fürstner, Alois,Jerabek, Paul,Lehmann, Christian W.,Martinez-Rodriguez, Luis,N?thling, Nils,Patzer, Michael,Pozo, Iago
supporting information, p. 2509 - 2515 (2020/02/26)
The Cu-catalyzed reaction of substituted α-diazoesters with fluoride gives α-fluoroesters with ee values of up to 95 %, provided that chiral indane-derived bis(oxazoline) ligands are used that carry bulky benzyl substituents at the bridge and moderately bulky isopropyl groups on their core. The apparently homogeneous solution of CsF in C6F6/hexafluoroisopropanol (HFIP) is the best reaction medium, but CsF in the biphasic mixture CH2Cl2/HFIP also provides good results. DFT studies suggest that fluoride initially attacks the Cu- rather than the C-atom of the transient donor/acceptor carbene intermediate. This unusual step is followed by 1,2-fluoride shift; for this migratory insertion to occur, the carbene must rotate about the Cu?C bond to ensure orbital overlap. The directionality of this rotatory movement within the C2-symmetric binding site determines the sense of induction. This model is in excellent accord with the absolute configuration of the resulting product as determined by X-ray diffraction using single crystals of this a priori wax-like material grown by capillary crystallization.
Copper(II)-catalyzed enantioselective intramolecular cyclization of N-alkenylureas
Fu, Shaomin,Yang, Honghao,Deng, Yuanfu,Jiang, Huanfeng,Zeng, Wei,Li, Guoqiang
supporting information, p. 1018 - 1021 (2015/03/30)
The first Cu(II)-catalyzed highly enantioselective intramolecular cyclization of N-alkenylureas was developed for the concise assembly of chiral vicinal diamino bicyclic heterocycles. Facile removal of carbonyl group of the carbamido moiety allowed for ready access to enantioenriched cyclic vicinal diamines.
Reactive resin facilitated preparation of an enantiopure fluorobicycloketone
Wong, Audrey,Welch, Christopher J.,Kuethe, Jeffrey T.,Vazquez, Enrique,Shaimi, Mohamed,Henderson, Derek,Davies, Ian W.,Hughes, David L.
, p. 168 - 174 (2007/10/03)
A facile preparation of enantiopure ethyl (1S,SS,6S)-6-fluoro-2-oxobicyclo[3.1.0]hexane-6-carboxylate 1 is described. The key feature of the synthesis involves copper-catalyzed enantioselective intramolecular cyclopropanation of a diazoketone to form enado-fluorocyclopropane 1 in a single operation. Removal of a problematic chloroketone impurity using a reactive resin treatment enabled a high throughput enantiopurity upgrade by chiral HPLC. The development of a scalable synthesis of 1 is presented, including details of the selection of catalyst and ligand optimization, incorporation of a reactive resin treatment and selection of chiral HPLC media and conditions.
