A base-mediated synthesis of N-hydroxy- and N-alkoxyindoles from 2-nitrostyrenes.

Sequential treatment of alkyl 2-(2-nitroaryl)-2-butenoates with potassium tert-butoxide and an electrophile, such as methyl iodide, benzyl bromide and allyl bromide, afforded N-alkoxyindoles. In related reactions, using sodium tert-pentoxide as the base with or without in situ addition of an electrophile afforded N-alkoxy- and N-hydroxyindoles, respectively. Electrophiles such as dimethylsulfate, p-tosyl chloride, and acetic anhydride afforded moderate yields of the respective N-methoxy-, N-tosyloxy, and N-acetoxyindoles, while methyl iodide, benzyl bromide, and 1-bromohexane failed to form alkylated products using sodium tert-pentoxide as the base.