1005210-14-9Relevant academic research and scientific papers
Practical Synthesis of Chiral N-Heterocyclic Carbene Triazolium Salts Containing a Hydroxy Functional Handle
Dhayalan, Vasudevan,Mal, Kanchan,Milo, Anat
, p. 2845 - 2864 (2019/07/04)
A library of functionalized chiral pyrrolidine-based N-heterocyclic carbene triazolium salts containing a hydroxy handle is prepared from readily accessible chiral (S)-pyroglutamic acid in eight steps. This improved synthetic protocol affords increased yields for known structures and 18 new NHCs are prepared by this method. The presence of a hydroxy handle offers potential for further functionalization and for non-covalent control over catalytic reactions in which the NHCs can serve as organocatalysts or ligands for organometallic catalysis.
Stereo- and Chemodivergent NHC-Promoted Functionalisation of Arylalkylketenes with Chloral
Douglas, James J.,Churchill, Gwydion,Slawin, Alexandra M. Z.,Fox, David J.,Smith, Andrew D.
supporting information, p. 16354 - 16358 (2015/11/09)
Stereo- and chemodivergent enantioselective reaction pathways are observed upon treatment of alkylarylketenes and trichloroacetaldehyde (chloral) with N-heterocyclic carbenes, giving selectively either β-lactones (up to 88:12 dr, up to 94% ee) or α-chloroesters (up to 94% ee). Either 2-arylsubstitution or an α-branched iPr alkyl substituent within the ketene favours the chlorination pathway, allowing chloral to be used as an electrophilic chlorinating reagent in asymmetric catalysis.
Catalytic enantioselective Steglich rearrangements using chiral N-heterocyclic carbenes
Campbell, Craig D.,Concellon, Carmen,Smith, Andrew D.
, p. 797 - 811 (2011/08/06)
The evaluation of a range of enantiomerically pure NHCs, prepared in situ from imidazolinium or triazolium salt precatalysts, to promote the catalytic enantioselective Steglich rearrangement of oxazolyl carbonates to their C-carboxyazlactones, is reported. Modest levels of enantioselectivity (up to 66% ee) are observed using oxazolidinone derived NHCs.
Synthesis of enantiopure triazolium salts from pyroglutamic acid and their evaluation in the benzoin condensation
Enders, Dieter,Han, Jianwei
, p. 1367 - 1371 (2008/12/20)
A family of enantiopure 1,2,4-triazolium salts were prepared starting from the inexpensive (S)-pyroglutamic acid. After treatment with base, the corresponding N-heterocyclic carbenes were tested as organocatalysts in the asymmetric benzoin condensation and gave good yields and up to 95% ee.
Asymmetric dimerization of disubstituted ketenes catalyzed by N-heterocyclic carbenes
Lv, Hui,Zhang, Yan-Rong,Huang, Xue-Liang,Ye, Song
supporting information; experimental part, p. 2715 - 2718 (2009/10/20)
A series of chiral N-heterocyclic carbenes (NHCs), derived from L-pyrogutamic acid, were found to be efficient catalysts for the asymmetric dimerization of alkylarylketenes to give the corresponding α-quaternary β-alkylidenyl-β-lactones in good yields with up to 97% ee. A chiral NHC with a proximal hydroxy group is superior in comparison with the corresponding NHC with its hydroxy group protected.
Chiral N-heterocyclic carbene catalyzed staudinger reaction of ketenes with imines: Highly enantioselective synthesis of N-boc β-lactams
Zhang, Yan-Rong,He, Lin,Wu, Xu,Shao, Pan-Lin,Ye, Song
, p. 277 - 280 (2008/09/19)
(Chemical Equation Presented) N-Heterocyclic carbenes (NHCs) were demonstrated to be efficient catalysts for the Staudinger reaction of ketenes with N-tosyl, N-benzyloxycarbonyl, or N-tert-butoxycarbonyl imines. Chiral NHC 8b, conveniently prepared from L
