Synthesis 2020; 52(17): 2551-2562
DOI: 10.1055/s-0040-1707907
paper
© Georg Thieme Verlag Stuttgart · New York

Stereoselective Synthesis of Spiro-α-methylene-γ-lactams via Chiral Quaternary 3-Aminooxindole Adducts Accessed by Zn-Mediated Allylation of Sulfinyl Ketimines

V. U. Bhaskara Rao
,
Shashank Singh
,
Krishna N. Tripathi
,
Ravi P. Singh
We are grateful for the generous financial support from the Science and Engineering Research Board, DST-India (EMR/2017/000319), the Council of Scientific and Industrial Research (CSIR), India [02(0254)/16/EMR-II], and the Board of Research in Nuclear Sciences, DAE (58/1408/2019-BRNS/10377). V.U.B.R. and K.N.T. thank CSIR for Senior Research Fellowships.
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Publication History

Received: 28 April 2020

Accepted after revision: 16 June 2020

Publication Date:
03 August 2020 (online)


§ Both authors contributed equally to this work.

Abstract

An efficient method for the stereoselective synthesis of α-methylene-γ-lactams via quaternary 3-aminooxindoles with very high selectivity (up to 98% ee) is described. The methodology leads to the construction of sterically congested chiral quaternary 3-aminooxindole adducts in good yield and with moderate to excellent diastereoselectivity (dr up to 95:5). The relative stereochemistry of the chiral quaternary 3-aminooxindoles adduct and the spiro-α-methylene-γ-lactam was confirmed to be syn by single-crystal X-ray structure analysis. Furthermore, the α-methylene-γ-lactam was successfully transformed into a range of chiral synthons.

Supporting Information