Davis–Beirut Reaction: A Photochemical Brønsted Acid Catalyzed Route to <i>N</i>-Aryl 2<i>H</i>-Indazoles
作者:Niklas Kraemer、Clarabella J. Li、Jie S. Zhu、Julio M. Larach、Ka Yi Tsui、Dean J. Tantillo、Makhluf J. Haddadin、Mark J. Kurth
DOI:10.1021/acs.orglett.9b02213
日期:2019.8.2
The Davis–Beirut reaction provides access to 2H-indazoles fromaromatic nitro compounds. However, N-aryl targets have been traditionally challenging to access due to competitive alternate reaction pathways. Previously, the key nitroso imine intermediate was generated under alkaline conditions, but as reported here, the photochemistry of o-nitrobenzyl alcohols empowered Brønsted acid catalyzed conditions
Nucleophilic Substitution of Oxazino-/Oxazolino-/Benzoxazin [3,2-<i>b</i>]indazoles: An Effective Route to 1<i>H</i>-Indazolones
作者:Michael B. Donald、Wayne E. Conrad、James S. Oakdale、Jeffrey D. Butler、Makhluf J. Haddadin、Mark J. Kurth
DOI:10.1021/ol100751n
日期:2010.6.4
A variety of nucleophiles, thiolates, alkoxides, amines, iodide, and cyanide, react with oxazino-, oxazolino-, and benzoxazin[3,2-b]indazoles under microwave conditions to yield a diverse set of 2-substituted 1H-indazolones. The synthetic utility of these indazoles is further demonstrated by ANRORC (addition of the nucleophile, ring-opening, and ring closure) reactions to yield isomeric pyrazoloindazolones by a process wherein iodide acts first as a nucleophile and subsequently as a leaving group.