Regioselective Protection at N-2 and Derivatization at C-3 of Indazoles

• Published in: Journal of organic chemistry Vol. 71; no. 14; pp. 5392 - 5395
• Main Authors: Luo, Guanglin, Chen, Ling, Dubowchik, Gene
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 07.07.2006; Amer Chemical Soc
• Subjects: Chemistry; Chemistry, Organic; 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; Physical Sciences; Preparations and properties; Science & Technology; Stereoisomerism; MILD; PYRAZOLES; CROSS-COUPLING REACTION; FLEXIBLE STRATEGY; ARYLATION; BASICITY; CATALYST; DERIVATIVES; EFFICIENT; 3-IODOINDAZOLES; Hydrogen Chlorides; Scanning electron microscopy; Regioselectivity; Nitrogen heterocycle; Organic silane; Derivatization; Indazole derivatives; Tetrahydrofurane; Lithiation; Ethanol derivatives; Protection; Electrophile; Nucleophile
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo060607j

Indazoles are regioselectively protected at N-2 by a 2-(trimethylsilyl)ethoxymethyl (SEM) group using novel conditions. The SEM group can efficiently direct regioselective C-3 lithiation, and the resulting nucleophile can react with a wide range of electrophiles to generate novel indazole derivatives. The SEM group can be removed by treatment with TBAF in THF or aqueous HCl in EtOH.