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

Abstract

The reaction of NH -indazoles with formaldehyde in aqueous hydrochloric acid has been experimentally studied by solution and solid-state nuclear magnetic resonance (NMR) and crystallography. The mechanism of the formation of N 1 -CH 2 OH derivatives was determined. For the first time, 2-substituted derivatives 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 for the experimental observations. The first X-ray structures of four (1 H -indazol-1-yl)methanol derivatives are reported.

Addition reaction of azoles to acetone‐d6: NMR and computational studies

“…As for the carbonyl type reagent, it would not only apply to propan‐2‐one, but also to other ketones, aldehydes, and related compounds such as imines. Some partial results are available: formaldehyde and indazole, 7b,89,90 benzimidazole 91 and benzotriazole 7b,92 ; as well as hexafluoroacetone with imidazole, benzimidazole and benzotriazole 93 . We hope that the results and methodology here used can contribute to this vast field.…”

A theoretical study of dynamic processes observed in trimethylsilyl-1H-pyrazoles: prototropy and silylotropy

“…a reference [39]; b reference [36]; c pure liquid: references [22,40] In the case of compound 1 in CD 3 OD at low temperature (-90 ºC), only H3, H5 and SiMe 3 were reported to appear at 7.70, 7.56 and 0, 21 ppm, respectively. The data of Table 1 were analyzed statistically using the calculated mean values; with regard to CDCl 3 , the other solvents (CCl 4 , CD 3 OD and "neat liquid") do not modify the values in a significant way; on the other hand, the NH proton of compound 1 differs significantly from the GIAO calculated value in the gas phase 9.06 vs. 12.97 and 14.58 ppm), a well-known fact [41]. In the following equation, NH variable corresponds to these differences but statistically calculated.…”

DFT Study on Mechanism of Ni–Al Bimetallic-Catalyzed C–H Cyclization to Construct Tricyclic Imidazoles: Roles of NHC Ligand and AlMe3

“…Tricyclic imidazoles and their 7-membered ring derivatives, as one of the most important classes of structural motifs, − are widely present in numerous biologically active material molecules. Owing to their significance, the synthesis of tricyclic imidazoles and their 7-membered ring derivatives − has attracted widespread attention, and extensive effort has been devoted to the development of new methodologies. − Among a large number of strategies, direct construction of a 7-membered ring via C7–H cyclization of benzimidazoles with alkenes would provide a more straightforward, atom- and step-economic access to tricyclic imidazoles from more easily accessible substrates.…”