Asymmetric Vinylogous Mannich Reaction of Silyloxy Furans with <i>N</i>-<i>tert</i>-Butanesulfinyl Ketimines

A highly regio- and diastereoselective TMSOTf promoted vinylogous Mannich reaction for the synthesis of chiral quaternary 3-amino­oxindole butenolides from 2-silyloxy furans and chiral ketimines is described. The method is found to be very efficient and also provides a facile access to sterically challenging 3-amino­oxindole butenolides bearing two quaternary centers in continuation. Further, the versatility of the method is demonstrated by the 1,4-addition of nucleophiles on the sterically congested butenolide substructure

Biomimetic Catalytic Retro-Aldol Reaction Using a Cation-Binding Catalyst: A Promising Route to Axially Chiral Biaryl Aldehydes

Here we describe a biomimetic catalytic retro-aldol reaction of racemic α-substituted β-hydroxy ketones utilizing a chiral oligoEG cation-binding catalyst as a type-II aldolase mimic. Our investigation of various aldol substrates has demonstrated that our biomimetic retro-aldol protocol enables rapid access to highly enantiomerically enriched aldols with a selectivity factor (s) of up to 70. Additionally, we have demonstrated the synthetic strategy’s feasibility for accessing diverse and valuable axially chiral aldehydes