Isothiourea-catalyzed enantioselective α-alkylation of esters via 1,6-conjugate addition to para-quinone methides
Abstract
The isothiourea-catalyzed enantioselective 1,6-conjugate addition of para-nitrophenyl esters to 2,6-disubstituted para-quinone methides is reported. para-Nitrophenoxide, generated in situ from initial N-acylation of the isothiourea by the para-nitrophenyl ester, is proposed to facilitate catalyst turnover in this transformation. A range of para-nitrophenyl ester products can be isolated, or derivatized in situ by addition of benzylamine to give amides, in up to 99% yield. Although low diastereocontrol is observed, the diastereoisomeric ester products are separable and formed with high enantiocontrol (up to 94:6 er).
Citation
Arokianathar , J N , Hartley , W , McLaughlin , C , Greenhalgh , M D , Stead , D , Ng , S , Slawin , A M Z & Smith , A D 2021 , ' Isothiourea-catalyzed enantioselective α-alkylation of esters via 1,6-conjugate addition to para -quinone methides ' , Molecules , vol. 26 , no. 21 , 6333 . https://doi.org/10.3390/molecules26216333
Publication
Molecules
Status
Peer reviewed
ISSN
1420-3049Type
Journal article
Description
Funding: We thank the ERC under the European Union's Seventh Framework Programme (FP7/2007-2013)/E.R.C. grant agreement n° 279850, AstraZeneca and EPSRC [EP/M506631/1 (J.N.A.)], Syngenta and the EPSRC Centre for Doctoral Training in Critical Resource Catalysis [CRITICAT, EP/L016419/1 (W.C.H.)], and EPSRC [EP/M508214/1 (C.M.)] for funding. A.D.S. thanks the Royal Society for a Wolfson Research Merit Award. We thank the EPSRC UK National Mass Spectrometry Facility at Swansea University.Collections
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