Synthesis of Indazoles by the [3+2] Cycloaddition of Diazo Compounds with Arynes and Subsequent Acyl Migration

• Published in: Journal of organic chemistry 2008-01, Vol.73 (1), p.219-226
• Main Authors: Liu, Zhijian, Shi, Feng, Martinez, Pablo D. G, Raminelli, Cristiano, Larock, Richard C
• Format: Article
• Language: English
• Subjects: Alkynes - chemistry; Azo Compounds - chemistry; Chemistry; Cyclization; Exact sciences and technology; Heterocyclic compounds; Heterocyclic compounds with several n hetero atoms in the same ring, in separated rings or in fused rings; Indazoles - chemical synthesis; Indazoles - chemistry; Molecular Structure; Organic chemistry; Preparations and properties; Stereoisomerism
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo702062n

The [3+2] cycloaddition of a variety of diazo compounds with o-(trimethylsilyl)aryl triflates in the presence of CsF or TBAF at room temperature provides a very direct, efficient approach to a wide range of potentially biologically and pharmaceutically interesting substituted indazoles in good to excellent yields under mild reaction conditions. Simple diazomethane derivatives afford N-unsubstituted indazoles or 1-arylated indazoles, depending upon the stoichiometry of the reagents and the reaction conditions, while dicarbonyl-containing diazo compounds undergo carbonyl migration to afford 1-acyl or 1-alkoxycarbonyl indazoles selectively.