Synthesis of chiral spiro-cyclopentene/cyclopentadiene-oxindoles through an asymmetric [3 + 2] cycloaddition of isatin-derived MBH carbonates and β,γ-unsaturated α-keto esters

• Published in: Tetrahedron Vol. 75; no. 21; pp. 2971 - 2979
• Main Authors: Chen, Yu, Cui, Bao-Dong, Bai, Mei, Han, Wen-Yong, Wan, Nan-Wei, Chen, Yong-Zheng
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 24-05-2019
• Subjects: Cycloaddition reaction; MBH carbonates; Spiro-cyclopentene-oxindoles; Cycloaddition reaction; MBH carbonates; Spiro-cyclopentene-oxindoles
• ISSN: 0040-4020; 1464-5416
• DOI: 10.1016/j.tet.2019.04.040

A highly stereoselective [3 + 2] cycloaddition for constructing the chiral spiro-cyclopentene/cyclopentadiene-oxindole skeletons is developed. Under the mild reaction conditions, the straightforward cyclization of isatin-derived MBH carbonates and β,γ-unsaturated α-keto esters involving a chiral tertiary amine catalyst provides the corresponding spirooxindole derivatives with an extraordinary level of diastereo- and enantioselectivities. Further synthetic utility of this protocol is demonstrated by the gram-scale experiment and functional transformation of the synthetic compound into other structurally diverse spirooxindole.
A highly stereoselective [3 + 2] cycloaddition for constructing the chiral spiro-cyclopentene/cyclopentadiene-oxindole skeletons is developed. Under the mild reaction conditions, the straightforward cyclization of isatin-derived MBH carbonates and β,γ-unsaturated α-keto esters involving a chiral tertiary amine catalyst provides the corresponding spirooxindole derivatives with an extraordinary level of diastereo- and enantioselectivities. Further synthetic utility of this protocol is demonstrated by the gram-scale experiment and functional transformation of the synthetic compound into other structurally diverse spirooxindole. [Display omitted]