Direct <i>ortho</i>-Selective Amination of 2‑Naphthol and Its Analogues with Hydrazines

Described herein is a regioselective ortho-amination of 2-naphthol and its analogues with substituted hydrazines. It provides a direct methodology for the synthesis of N-arylaminated naphthol derivatives without the formation of related 1,1′-biaryl-2,2′-diamine or carbazole byproducts. Specifically, using N,N-disubstituted hydrazine precursors, N-unsubstituted ortho-aminated derivatives and related secondary amines can be formed in ethylene glycol in moderate to excellent yields. Variation of substrates to N,N′-diarylhydrazines and N-methyl-N,N′-diarylhydrazines led to N-aryl-1-amino-2-naphthol compounds. It is noted that biologically interesting indazole motifs can be facilely created by the reaction of N,N′-dialkylhydrazines with 2-naphthols. These ortho-amination reactions have the advantage of one-pot operation without the use of transition metal catalysts.