NHC-catalyzed ester activation : access to sterically congested spirocyclic oxindoles via reaction of α-aryl esters and unsaturated imines

• Main Authors: Hao, Lin, Chuen, Chan Wei, Ganguly, Rakesh, Chi, Robin Yonggui
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2014
• Subjects: DRNTU::Science::Chemistry::Organic chemistry
• Online Access: https://hdl.handle.net/10356/104221; http://hdl.handle.net/10220/19449
• Institution: Nanyang Technological University

Carboxylic esters can be readily obtained at low cost. Therefore, asymmetric catalytic activation of esters should provide useful strategies for organic synthesis. Here we report a N-heterocyclic carbene (NHC)-mediated reaction of α-aryl acetic esters with oxindole-derived α,β-unsaturated imines. The reaction involves the formation of NHC-bound ester enolate intermediate from an ester as a key step, and furnishes spirocyclic oxindole products. The sterically congested spirocyclic oxindole bears a newly formed six-membered δ-lactams and cannot be easily prepared using other methods.