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Solid-phase Synthesis of [4.4] Spirocyclic Oximes
Published on: February 6, 2019
Trienamine catalysed unprecedented remote olefin E/Z isomerisation/[4 + 2]-cycloaddition reaction to access
Madavi S Prasad1, Murugesan Sivaprakash1, Sankar Bharani1
1Asymmetric Synthesis and Catalysis Laboratory, Department of Chemistry, Central University of Tamil Nadu (CUTN), Tiruvarur-610 005, India. shivaprasad@cutn.ac.in.
Abstract:
Herein, for the first time, we report the asymmetric synthesis of an unexpected stereoisomer of spirohexahydroindole via a trienamine-catalysed remote olefin E/Z isomerisation/[4 + 2]-cycloaddition reaction. The reaction afforded a vast library of aesthetically pleasing spirooxindole hexahydroindole scaffolds with exceptional enantio- and diastereo-selectivities (up to 95% yield, 99% ee and >99 : 1 dr). In addition, we demonstrated the synthetic transformation of enantiomerically pure spirooxindole hexahydroindoles to synthesize alkyl homologated spirooxindole hexahydroindole and fluoro-pyranooctahydroindole moieties with four and seven contiguous stereocenters, respectively, in excellent yield and selectivities. We have also demonstrated the evidence for the proposed pathway through NMR investigations.
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