Difluoroacetaldehyde
<i>N</i>
‐Triftosylhydrazone (DFHZ‐Tfs) as a Bench‐Stable Crystalline Diazo Surrogate for Diazoacetaldehyde and Difluorodiazoethane
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 (CHOCHN2 ) or difluorodiazoethane (CF2 HCHN2 ), in a controlled fashion under specific conditions. DFHZ-Tfs has been successfully employed in the Fe-catalyzed cyclopropanation and Doyle-Kirmse
[4 + 1] Annulation of in situ generated azoalkenes with amines: A powerful approach to access 1-substituted 1,2,3-triazoles
作者:Hongwei Wang、Yongquan Ning、Paramasivam Sivaguru、Giuseppe Zanoni、Xihe Bi
DOI:10.1016/j.cclet.2021.09.008
日期:2022.3
methods for their preparation mainly rely on thermal [3 + 2] cycloaddition of potentially dangerous acetylene and azides. Here we report a base-mediated [4 + 1] annulation of azoalkenes generated in situ from readily available difluoroacetaldehyde N-tosylhydrazones (DFHZ-Ts) with amines under relatively mild conditions. This azide- and acetylene-free strategy provides facile access to diverse 1-substituted
Palladium-Catalyzed Carbene Coupling Reactions of Cyclobutanone <i>N</i>-Sulfonylhydrazones
作者:Xiaoqin Ning、Yongke Chen、Fangdong Hu、Ying Xia
DOI:10.1021/acs.orglett.1c03052
日期:2021.11.5
Described herein are the palladium-catalyzed cross-couplingreactions of cyclobutanone-derived N-sulfonylhydrazones with aryl or benzyl halides, suggesting that the metal carbene process and β-hydride elimination can smoothly occur in strained ring systems. Structurally diversified products including cyclobutenes, methylenecyclobutanes, and conjugated dienes are selectively afforded in good to excellent
Cycloaddition of Trifluoroacetaldehyde <i>N</i>-Triftosylhydrazone (TFHZ-Tfs) with Alkynes for Synthesizing 3-Trifluoromethylpyrazoles
作者:Hongwei Wang、Yongquan Ning、Yue Sun、Paramasivam Sivaguru、Xihe Bi
DOI:10.1021/acs.orglett.0c00395
日期:2020.3.6
(TFHZ-Tfs) and alkynes is reported. This protocol provides an operationally simple and general method for the synthesis of diverse 3-trifluoromethylpyrazoles in good to excellent yields with broad substrate scope, including aryl, heteroaryl, and alkyl terminalalkynes, and electron-deficient internalalkynes. The synthetic potential of this method was further demonstrated by the synthesis of an antiarthritic
Defluorinative [4 + 1] annulation of perfluoroalkyl <i>N</i>-mesylhydrazones with primary amines provides 5-fluoroalkyl 1,2,3-triazoles
作者:Yongquan Ning、Hongwei Wang、Paramasivam Sivaguru、Shuang Li、Giuseppe Zanoni、Steven P. Nolan、Xihe Bi
DOI:10.1039/d1gc02749b
日期:——
blocks. However, only a few synthetic routes to these compounds are currently available. Herein, we report on a novel method to access 5-fluoroalkyl 1,2,3-triazoles from easily prepared bench-stable perfluoroalkyl N-mesylhydrazone (PFHZ-Ms), a reagent that can transform amines to 5 fluoroalkyl 1,2,3-triazoles via defluorinative [4 + 1] annulation. The simple reaction protocol can be applied to a variety