Bromide ion → 1-(1H-indazol-1-yl)ethanone

Participants

Reaction Steps

To prepare 1-substituted 1H-indazole of formula 1 wherein R1 is formyl, alkanoyl, cycloalkylalkanoyl ##STR45## wherein R2', R5, X", p" and q' are as above, a 1-unsubstituted 1H-indazole 8 wherein R is as above, with the proviso that R is not hydrogen, and X, m, n and p are as before, is treated, respectively, with a formyl, alkanoyl or cycloalkylalkanoyl chloride, bromide or iodide, a compound of the formula ##STR46## R2'OCOHal or R5COHal wherein R2', R5, X", p" and q' are as above and Hal is iodo, bromo or chloro, or the corresponding acid anhydrides thereof, at an elevated temperature of about the reflux temperature of the reaction medium. For example, treatment of a 1H-indazole 8 wherein R is methyl with acetic anhydride at the reflux temperature of the reaction mixture affords a 1-acetyl-1H-indazole 14 wherein R2 is methyl, and treatment of a 1H-indazole 8 wherein R is methyl with benzoyl chloride at a reaction temperature of about 100° C. yields a 1-benzoyl-1H-indazole 14 wherein R2 is phenyl.

Provenance & Evidence