Regiodivergent Synthesis of 4,5'- and 4,4'-Imidazolinyl Spiropyrazolones from 4-Alkylidene Pyrazolones and Amidines

Hui Xu; Ran Hong; Ming-Yue Weng; Rong-Lu Huang; Guan-Wu Wang; Ze Zhang

doi:10.1021/acs.orglett.1c01475

Regiodivergent Synthesis of 4,5'- and 4,4'-Imidazolinyl Spiropyrazolones from 4-Alkylidene Pyrazolones and Amidines

Org Lett. 2021 Jul 16;23(14):5305-5310. doi: 10.1021/acs.orglett.1c01475. Epub 2021 Jul 2.

Authors

Hui Xu^{1

2}, Ran Hong¹, Ming-Yue Weng¹, Rong-Lu Huang¹, Guan-Wu Wang², Ze Zhang¹

Affiliations

¹ Anhui Province Key Laboratory of Functional Coordinated Complexes for Materials Chemistry Application and School of Chemical and Environmental Engineering, Anhui Polytechnic University, Wuhu 241000, P. R. China.
² CAS Key Laboratory of Soft Matter Chemistry, Hefei National Laboratory for Physical Sciences at Microscale, and Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China.

PMID: 34213352
DOI: 10.1021/acs.orglett.1c01475

Abstract

The solvent-free reaction of 4-alkylidene pyrazolones with amidines can furnish 4,5'-imidazolinyl spiropyrazolones in good to excellent yields when promoted by N-iodosuccinimide under solvent-free ball-milling conditions, whereas it almost exclusively affords 4,4'-imidazolinyl spiropyrazolones if mediated by N-bromosuccinimide in heated toluene. On the basis of this switchable cyclization strategy, a powerful metal-free method for regioselective and diastereoselective synthesis of structurally diverse 4,5'- and 4,4'-imidazolinyl spiropyrazolones has been successfully developed.

Publication types

Research Support, Non-U.S. Gov't