The Davis–Beirut Reaction: <i>N</i>¹,<i>N</i>²-Disubstituted-1<i>H</i>-Indazolones via 1,6-Electrophilic Addition to 3-Alkoxy-2<i>H</i>-Indazoles

Abstract

A variety of electrophiles (anhydrides, acid chlorides, carbonochloridates, sulfonyl chlorides, and alkyl bromides) react with 3-methoxy-2H-indazole (1a), benzoxazin[3,2-b]indazole (1d), and oxazolino[3,2-b]indazole (1e) - substrates available by the Davis-Beirut reaction - to yield a diverse set of N(1),N(2)-disubstituted-1H-indazolones. With certain electrophiles, an AERORC (Addition of the Electrophile, Ring Opening, and Ring Closure) process on indazole 1d results in indazoloindazolone formation. An intriguing aspect of these N(1),N(2)-disubstituted-1H-indazolones is that they are poised for diversification through, for example, azide-alkyne cycloaddition chemistry reported here.