Study of the Addition Mechanism of 1H-Indazole and Its 4-,5-,6-,and 7-Nitro Derivatives to Formaldehyde in Aqueous HydrochloricAcid Solutions

The reaction ofNH-indazoles with formaldehyde inaqueous hydrochloric acid has been experimentally studied bysolution and solid-state nuclear magnetic resonance (NMR) andcrystallography. The mechanism of the formation ofN1-CH2OHderivatives was determined. For thefirst time, 2-substitutedderivatives have been characterized by multinuclear NMR.Theoretically, calculations with gauge-invariant atomic orbitals(GIAOs) at the Becke three-parameter (exchange) Lee-Yang-Parr B3LYP/6-311++G(d,p) level have provided a sound basis forthe experimental observations. Thefirst X-ray structures of four(1H-indazol-1-yl)methanol derivatives are reported

Automated summary

The reaction between NH-indazoles and formaldehyde in aqueous hydrochloric acid was experimentally studied using solution and solid-state nuclear magnetic resonance and crystallography. The mechanism of N1-CH2OH derivative formation was determined. For the first time, 2-substituted derivatives were characterized using multinuclear NMR. Theoretical calculations supported the experimental observations. Additionally, the X-ray structures of four new (1H-indazol-1-yl)methanol derivatives were reported.