Enantioselective Synthesis of Thiazolopyran Derivatives via a Direct Vinylogous Michael-oxa-Michael Sequence
Abhijit Manna1, Shweta Rohilla1, Vinod K Singh1
1Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208 016, India.
Abstract:
An efficient diastereo- and enantioselective direct vinylogous Michael-oxa-Michael sequence between 5-alkenyl thiazolones and isopropylidene oxindoles has been developed. The reaction is catalyzed by a bifunctional squaramide catalyst that allows to access a wide range of densely substituted thiazolopyran derivatives containing a quaternary stereocenter. This protocol is flexible toward different sterically and electronically tuned substrates and is amenable to gram-scale synthesis and several synthetic transformations.
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