Ex Situ Generation of Difluorodiazoethane (CF2HCHN2): Application in the Regioselective Synthesis of CF2H‑Containing Pyrazoles

A new method for the ex situ generation of difluorodiazoethane (CF2HCHN2) and a procedure for its efficient use in [3 + 2] cycloaddition with nitroolefins by the AcOH/O2 catalyst system were developed by using a simple two-chamber system. The method provides a facile and straightforward access to a...

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Bibliographic Details
Published in:Organic letters 2019-11, Vol.21 (21), p.8751-8755
Main Authors: Wang, Jian-Shu, Huang, Kai-Shun, Han, Wen-Yong, Cui, Bao-Dong, Wan, Nan-Wei, Chen, Yong-Zheng
Format: Article
Language:English
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Summary:A new method for the ex situ generation of difluorodiazoethane (CF2HCHN2) and a procedure for its efficient use in [3 + 2] cycloaddition with nitroolefins by the AcOH/O2 catalyst system were developed by using a simple two-chamber system. The method provides a facile and straightforward access to a series of 4-substituted 5-difluoromethyl-3-nitro-1H-pyrazoles that are of interest in medicinal chemistry. Interestingly, the key factor for the success of this method is the efficient preparation of CF2HCHN2 by an ex situ process.
ISSN:1523-7060
1523-7052
DOI:10.1021/acs.orglett.9b03371