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Stereo‐ and Chemodivergent NHC‐Promoted Functionalisation of Arylalkylketenes with Chloral
Author(s) -
Douglas James J.,
Churchill Gwydion,
Slawin Alexandra M. Z.,
Fox David J.,
Smith Andrew D.
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201503308
Subject(s) - chloral , enantioselective synthesis , ketene , electrophile , reagent , chemistry , substituent , catalysis , organic chemistry , combinatorial chemistry
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 i Pr alkyl substituent within the ketene favours the chlorination pathway, allowing chloral to be used as an electrophilic chlorinating reagent in asymmetric catalysis.