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Short Paper | Special issue | Vol 101, No. 1, 2020, pp.339-346
Published online, 7th August, 2019
DOI: 10.3987/COM-19-S(F)26
Intramolecular Oxa-Michael Reactions of Aldols Generated from Enones and Isatins to Afford Spirooxindole Tetrahydropyrans

Maira Pasha, Muhammad Sohail, and Fujie Tanaka*

*Chemistry and Chemical Bioengineering Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna, Okinawa 904-0495, Japan

Abstract

Spirooxindole derivatives are found in bioactive natural products and are used in drug discovery and related research. Here, acid-catalyzed diastereoselective intramolecular oxa-Michael cyclization reactions of β-hydroxyenones generated from enones and isatin derivatives that afford spirooxindole tetrahydropyrans are reported. The major diastereomers of the products of these reactions were previously difficult to access by the amine-catalyzed hetero-Diels-Alder reactions of enones with isatins. With the use of enantiomerically enriched forms of the starting materials in the reactions, enantiomerically enriched spirooxindole tetrahydropyrans that retained the enantiopurities of the starting materials were obtained.