Catalyst-Controlled Diastereoselectivity Switch in the Asymmetric [3 + 2] Annulation of Isatin-Derived MBH Carbonates and 5‑Alkenylthiazol-4(5H)‑ones

Exploration of the diastereodivergent synthesis of spirocyclic oxindoles has been challenging. Herein we report asymmetric [3 + 2] annulations of isatin-derived Morita–Baylis–Hillman (MBH) carbonates and 5-alkenylthiazol-4­(5H)-ones. Interestingly, two different chiral catalysts, amide-phosphine and...

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Bibliographic Details
Published in:Organic letters 2021-10, Vol.23 (19), p.7336-7341
Main Authors: Mei, Ming-Shun, Wang, Ya-Jie, Zhang, Gui-Shan, Tang, Jing-Yi, Tian, Ping, Wang, Yu-Hui
Format: Article
Language:English
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Summary:Exploration of the diastereodivergent synthesis of spirocyclic oxindoles has been challenging. Herein we report asymmetric [3 + 2] annulations of isatin-derived Morita–Baylis–Hillman (MBH) carbonates and 5-alkenylthiazol-4­(5H)-ones. Interestingly, two different chiral catalysts, amide-phosphine and 4-dimethylaminopyridine (DMAP)-thiourea, could lead to two kinds of diastereomeric dispiro oxindoles with three contiguous stereogenic centers. The hexafluoroisopropanol (HFIP) additive plays a vital role in accelerating the reaction and tuning the diastereoselectivity. Moreover, both annulation adducts could be further converted to structurally diverse spirooxindoles.
ISSN:1523-7060
1523-7052
DOI:10.1021/acs.orglett.1c02421