Iron(iii)-catalyzed selective N–O bond cleavage to prepare tetrasubstituted pyridines and 3,5-disubstituted isoxazolines from N-vinyl-α,β-unsaturated ketonitrones

Abstract

An iron(iii)-controlled selective N–O bond cleavage was developed for the synthesis of tetrasubstituted pyridines and isoxazolines from N-vinyl-α,β-unsaturated ketonitrones.

3-Benzoylisoxazolines by 1,3-Dipolar Cycloaddition: Chloramine-T-Catalyzed Condensation of α-Nitroketones with Dipolarophiles

“…The structures of produced compounds were firmly confirmed by 13 C NMR and 1 H NMR spectra and supported by HRMS, IR data (see the Supplementary Materials). 1 H NMR (400 MHz) and 13 C NMR (101 MHz) were recorded at room temperature by using a DRX-400 spectrometer (Bruker, Germany) in CDCl 3 . Chemical shifts were given in parts per million (ppm) on the delta (δ) scale.…”

“…Yield 72%. 1 H NMR (400 MHz, CDCl 3 ) 1 H NMR (400 MHz, CDCl 3 ) δ 8.04-7.97 (m, 2H), 7.62-7.56 (m, 2H), 7.35-7.30 (m, 2H), 7.25 (m, 3H), 5.07 (ddt, J = 10.9, 7.9, 6.3 Hz, 1H), 3.34 (dd, J = 17.6, 10.9 Hz, 1H), 3.13-3.05 (m, 2H), 2.96 (dd, J = 14.0, 6.5 Hz, 1H). ; 13…”

“…Isoxazoline derivatives have been demonstrated to exhibit a variety of biological and pharmacological activities, such as antithrombotic effects, insect growth regulation, immunopotentiation and anticancer activities (Figure 1) [1][2][3][4][5]. In organic synthesis, isoxazolines are also useful intermediates.…”

Stereoselective Synthesis of 4,5‐Dihydroisoxazole Derivatives from 1,1‐Dicyanocyclopropanes and Hydroxylamine Hydrochloride

“…Another most efficient strategy based on the 1,3‐dipolar cyclic addition reactions of alkenes or alkynes and nitrile oxides, formed readily from aldoximes or nitroalkanes, also was burgeoned [47–61] . Furthermore, other powerful protocols involving oximes [62,63] and hydroxylamines [64–66] have also been described employing intramolecular cyclization.…”

Yb(OTf)3‐Catalyzed Cycloaddition/[3,3]‐Rearrangement of N‐Vinyl‐α,β‐Unsaturated Ketonitrones with Methylenecycloprop‐anes: Stereoselective Synthesis of Nine‐Membered Nitrogen Heterocycles

“…[11] N-Vinyl nitrones, a distinct type of nitrone, have been shown to be powerful synthons because the double bond at the nitrone N-atom can be introduced into target molecules through various transformations. [12] During studies on nitrones and their cycloadditions, [13] we recently developed a novel strategy for the highly diastereoselective synthesis of nine-membered ring scaffolds though a [3 + 2] cycloaddition and sequential [3,3]-rearrangement cascade strategy from N-vinyl-α,β-unsaturated ketonitrones and various electrophiles, including arynes, isocyanates, and activated alkynes (Scheme 1-A). [14] To construct three stereocenters in the nine-membered rings, we proposed that N-vinyl-α,β-unsaturated ketonitrones and methylenecyclopropanes (MCPs) would undergo cycloaddition and sequential [3,3]-rearrangement to afford formal [7 + 2] cycloaddition products containing three stereocenters (Scheme 1-B).…”