A new method for the generation of difluorodiazoethane (CFHCHN) and a procedure for its efficient use in [3 + 2] cycloaddition with nitroolefins by the AcOH/O 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-1-pyrazoles that are of interest in medicinal chemistry. Interestingly, the key factor for the success of this method is the efficient preparation of CFHCHN by an process.
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http://dx.doi.org/10.1021/acs.orglett.9b03371 | DOI Listing |
Angew Chem Int Ed Engl
April 2020
Department of Chemistry, Northeast Normal University, Changchun, 130024, China.
Despite the growing importance of volatile functionalized diazoalkanes in organic synthesis, their safe generation and utilization remain a formidable challenge because of their difficult handling along with storage and security issues. In this study, we developed a bench-stable difluoroacetaldehyde N-triftosylhydrazone (DFHZ-Tfs) as an operationally safe diazo surrogate that can release in situ two low-molecular-weight diazoalkanes, diazoacetaldehyde (CHOCHN ) or difluorodiazoethane (CF HCHN ), in a controlled fashion under specific conditions. DFHZ-Tfs has been successfully employed in the Fe-catalyzed cyclopropanation and Doyle-Kirmse reactions, thus highlighting the synthetic utility of DFHZ-Tfs in the efficient construction of molecule frameworks containing CHO or CF H groups.
View Article and Find Full Text PDFOrg Lett
November 2019
Key Laboratory of Biocatalysis & Chiral Drug Synthesis of Guizhou Province, Generic Drug Research Center of Guizhou Province, School of Pharmacy , Zunyi Medical University, Zunyi 563006 , P. R. China.
A new method for the generation of difluorodiazoethane (CFHCHN) and a procedure for its efficient use in [3 + 2] cycloaddition with nitroolefins by the AcOH/O 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-1-pyrazoles that are of interest in medicinal chemistry. Interestingly, the key factor for the success of this method is the efficient preparation of CFHCHN by an process.
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