Fig. 5.

Mechanistic investigation of the reactions between 1,4-DNIms and amines. a 1,4-DNIm 1a reacts with ¹⁵N-labeled aniline to produce (1e). The CCDC reference number of compound 1e is 1876959. HRMS (ESI) analysis of product (1e): m/z calcd. for C₉H₈N₂¹⁵NO₂ [M + H]⁺ 191.0587, found 191.0577; m/z calcd. for C₉H₇N₂¹⁵NNaO₂ [M + Na]⁺ 213.0406, found 213.0400. b 2-isopropylaninline reacts with 2-methyl-1,4-DNIm 2d. HRMS (ESI) analysis of intermediate (1g): m/z calcd. for C₁₃H₁₇N₅NaO₄ [M + Na]⁺ 330.1178, found 330.1172; c UV–Vis characterization of products 1f and 1g