Cooperative palladium/isothiourea catalyzed enantioselective formal (3+2) cycloaddition of vinylcyclopropanes and α,β-unsaturated esters
Abstract
A protocol for the enantioselective synthesis of substituted vinylcyclopentanes has been realised using cooperative palladium and isothiourea catalysis. Treatment of vinylcyclopropanes with Pd(PPh3)4 generates a zwitterionic π-allyl palladium intermediate that intercepts a catalytically generated α,β-unsaturated acyl ammonium species prepared from the corresponding α,β-unsaturated para-nitrophenyl ester and the isothiourea (R)-BTM. Intermolecular formal (3+2) cycloaddition between these reactive intermediates generates functionalised cyclopentanes in generally good yields and excellent diastereo- and enantiocontrol (up to >95 : 5 dr, 97 : 3 er), with the use of LiCl as an additive proving essential for optimal stereocontrol. To the best of our knowledge a dual transition metal/organocatalytic process involving α,β-unsaturated acyl ammonium intermediates has not been demonstrated previously.
Citation
Bitai , J , Nimmo , A , Slawin , A M Z & Smith , A D 2022 , ' Cooperative palladium/isothiourea catalyzed enantioselective formal (3+2) cycloaddition of vinylcyclopropanes and α,β-unsaturated esters ' , Angewandte Chemie International Edition , vol. 61 , no. 25 , e202202621 . https://doi.org/10.1002/anie.202202621
Publication
Angewandte Chemie International Edition
Status
Peer reviewed
ISSN
1433-7851Type
Journal article
Description
The research leading to these results has received funding from the University of St Andrews (JB) and the EaSI-CAT centre for Doctoral Training (AJN).Collections
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