Reduction of Different Electron‐Poor N‐Heteroarylhydrazines in Strong Basic Conditions

Abstract

The first application of the Wolff-Kishner reduction methodology to electron-poor heteroaromatic compounds is reported. Hydrazino-containing heterocycles with hydrazone-type tautomery have been reduced under basic conditions. This novel chemistry was successfully applied to mono-dehalogenate a number of electron-poor heterocycles in a regioselective manner. According to the experimental results, this reductive process is a base-catalyzed reaction that takes only place in the presence of air, probably through an oxygen-assisted mechanism. As consequence of the specific features of this kind of hydrazone/enehydrazine tautomers, the overall outcome of the process is the synthesis of a Shapiro-type reduction product by simply using a milder version of the Huang-Minlon methodology.

A facile approach to [1,2,4]triazolo[3,4‐i]purine via PIDA oxidation ring‐closing reaction

“…To optimize the reaction conditions, 6-(2-benzylidenehydrazinyl)-9-butyl purine (1a) was selected as a model substrate which was prepared from 9-butyl-6-hydrazinyl purine [12][13][14] and the results were shown in Table 1. First, various common oxidants such as I 2 , OXONE, DTBP, TBHP, K 2 S 2 O 8 were tested (entry 1-6, Table 1).…”

“…All solvents and chemical reagents are purchased from commercial sources and can be used without further purification. All 1 H NMR (500 MHz), 13 C NMR (125 MHz), and 19 F NMR (470 MHz) spectra were recorded on a Bruker spectrometer in CDCl 3 or DMSO-d 6 . Tetramethylsilane (TMS) served as an internal standard (δ = 0) for 1 H NMR, CDCl 3 (δ = 77.0), and DMSO (δ = 39.5) were used as internal standards for 13 C NMR, respectively.…”

“…All 1 H NMR (500 MHz), 13 C NMR (125 MHz), and 19 F NMR (470 MHz) spectra were recorded on a Bruker spectrometer in CDCl 3 or DMSO-d 6 . Tetramethylsilane (TMS) served as an internal standard (δ = 0) for 1 H NMR, CDCl 3 (δ = 77.0), and DMSO (δ = 39.5) were used as internal standards for 13 C NMR, respectively. Mass spectra were recorded by the Q Extractive high-resolution mass spectrometry of Thermo Fisher.…”

Metal complexes of 6-pyrazolylpurine derivatives as models for metal-mediated base pairs

“…6-Hydrazinylpurine and 6-pyrazol-1-yl-purine 6 were synthesized according to literature procedures [42,43]. ESI-TOF measurements of compounds 1, 2, 3 and 7 were performed using the oa-TOF mass spectrometer MicrOTOF (Bruker Daltonik GmbH, Bremen, Germany) equipped with a standard ESI source.…”

Amide-controlled, one-pot synthesis of tri-substituted purines generates structural diversity and analogues with trypanocidal activity

“…The synthesis of purine rings from diaminopyrimidines using both aromatic and aliphatic aldehydes and an iron catalyst has also been previously described33. Furthermore, evidences of metal-free oxygen-promoted oxidation of electron-poor heterocycles in strong basic conditions have been shown by us34 and others35. With these precedents in mind, a set of reactions using reagents with large substituents (so that Route B pathway was to be favored) were designed to shed some light on the oxidative aspects of route B mechanism.…”