Acid-Promoted Bicyclization of Diaryl Alkynes: Synthesis of 2H-Indazoles with in Situ Generated Diazonium Salt as Nitrogen Source

作者：Zhang, Cheng; Chang, Sailan; Dong, Shanliang; Qiu, Lihua^*; Xu, Xinfang^*

来源：Journal of Organic Chemistry, 2018, 83(16): 9125-9136.

DOI：10.1021/acs.joc.8b01199

• CATALYZED CARBENE/ALKYNE METATHESIS
• 1,3-DIPOLAR CYCLOADDITION
• CASCADE REACTION
• HIGHLY POTENT
• INDAZOLES
• FUNCTIONALIZATION
• CYCLIZATION
• EFFICIENT
• HYDRATION
• ACCESS

An unprecedented transition-metal-free tandem bicyclization of diaryl alkynes has been disclosed, which provides a streamlined access to a range of polycyclic 2H-indazoles in high to excellent yields. The salient features of this reaction include readily available starting materials, good functional group compatibility, mild reaction conditions, no column chromatography, high bond-formation efficiency, and ease in further transformations. Notably, this is the first example for the synthesis of 2H-indazoles with in situ generated diazonium salt as the nitrogen source, and a mechanistic rationale involving an acid-promoted tandem diazonium salt formation/bicyclization process is discussed.

• 出版日期2018-8-17
• 单位苏州大学; 中山大学