Abstract
Nitroarenes are important intermediates in the synthesis of dyes, pharmaceuticals,
and functional materials. The nitro group serves as a key precursor to amines, which
have been widely employed in ortho-C(sp²)–H bond activation. Although the conventional electrophilic nitration of aniline
using a strong acid mixture is well established, it suffers from several drawbacks,
including the generation of acidic waste, low yields, poor selectivity, over-nitration,
and limited functional group tolerance. As an alternative, transition-metal-catalyzed,
directing-group-assisted regiospecific ortho-nitration of arene C–H bonds has emerged as a more efficient, convenient, atom- and
step-economical approach that can proceed under mild conditions. In addition, various
transition metal nitrates have demonstrated potential in the selective electrophilic
nitration of anilines. However, ortho/para-mixtures of regioisomers are obtained in some cases. This review article summarizes
all such recent advancements in the nitration reaction of protected anilines using
a range of nitrating agents.
Keywords
Anilines - C–H functionalization - Metal nitrates - Transition metals -
ortho-Nitration
