Enantioselective synthesis of spiro- N, O-ketals via iridium and Brønsted acid co-catalyzed asymmetric formal [4+2] cycloaddition

Xiang-Qi Xie; Xingguang Li; Pei-Nian Liu

doi:10.1039/d3cc05923e

Enantioselective synthesis of spiro- N, O-ketals via iridium and Brønsted acid co-catalyzed asymmetric formal [4+2] cycloaddition

Chem Commun (Camb). 2024 Feb 1;60(11):1448-1451. doi: 10.1039/d3cc05923e.

Authors

Xiang-Qi Xie¹, Xingguang Li¹, Pei-Nian Liu¹

Affiliation

¹ Shanghai Key Laboratory of Functional Materials Chemistry, Key Laboratory for Advanced Materials, School of Chemistry and Molecular Engineering, East China University of Science & Technology, Shanghai 200237, China. lixingguang@ecust.edu.cn.

PMID: 38213273
DOI: 10.1039/d3cc05923e

Abstract

We present an iridium and Brønsted acid co-catalyzed enantioselective formal [4+2] cycloaddition reaction of cyclic enamides with 2-(1-hydroxyallyl)phenols. This method yields a wide range of N-unsubstituted spiro-N,O-ketals, with good efficiency (up to 94%) and excellent enantioselectivities (most >95% ee). The protocol features easy scale-up and facile product derivatization.