( E )-1-(5-Methyl-1-(4-nitrophenyl)-1 H -1,2,3-triazol-4-yl)ethan-1-one Oxime

: The reaction of 1-(5-methyl-1-(4-nitrophenyl)-1 H -1,2,3-triazol-4-yl)ethan-1-one ( 1 ) with excess hydroxylamine hydrochloride (2 mole equivalents) in dry ethanol afforded ( E )-1-(5-methyl-1-(4-nitrophenyl)-1 H -1,2,3-triazol-4-yl)ethan-1-one oxime ( 2 ) in 86% yield. The structure of the new heterocycle 2 was conﬁrmed using nuclear magnetic resonance spectroscopy, single crystal X-ray and elemental analysis.


Introduction
Oximes are a class of imines with the general formula R 1 R 2 C=N-OH.They are primarily obtained from condensing hydroxylamine and carbonyl compounds (aldehydes or ketones).Aldoximes are produced from aldehyde, whereas ketoximes are synthesized from ketones [1][2][3].Oximes have unique properties and act as nucleophiles due to the presence of nitrogen and oxygen atoms.In addition, oximes contain an ambiphilic carbon and are considered strong candidates for divergent reactivity [4].

NMR Spectroscopy
The 1 H NMR spectrum of 2 showed the presence of an exchangeable singlet that appeared at 11.28 ppm due to the hydroxyl proton.In addition, it showed the presence of two methyl groups that appeared at 2.23 and 2.48 ppm.The protons of the aryl ring appeared as two doublets (J = 9.1 Hz) at 7.92 and 8.4q ppm.The 13 C NMR spectrum of 2 showed the C=N-OH carbon appeared at a high downfield at 154.2 ppm.The two methyl carbons appeared at 15.8 and 17.3 ppm, and C1 and C4 of the aryl ring appeared at 145.8 and 152.9 ppm, respectively.See Supplementary materials for details.
The nitro group of molecule M2 was coplanar with the benzene ring it was attached to (the twist angle was 5.9(3)°), whereas the group was disordered in M1, with twists of approximately 15° from the plane of the corresponding benzene ring.The triazole and (ethylidene)hydroxylamine groups were coplanar in both molecules, with twist angles M1B/M1C and M2B/M2C of 4.38(15)° and 7.77(12)°, respectively.In both molecules, the benzene rings were twisted from the planes of the triazole ring with twist angles of 35.7(1)° and 47.7(1)°.

NMR Spectroscopy
The 1 H NMR spectrum of 2 showed the presence of an exchangeable singlet that appeared at 11.28 ppm due to the hydroxyl proton.In addition, it showed the presence of two methyl groups that appeared at 2.23 and 2.48 ppm.The protons of the aryl ring appeared as two doublets (J = 9.1 Hz) at 7.92 and 8.4q ppm.The 13 C NMR spectrum of 2 showed the C=N-OH carbon appeared at a high downfield at 154.2 ppm.The two methyl carbons appeared at 15.8 and 17.3 ppm, and C1 and C4 of the aryl ring appeared at 145.8 and 152.9 ppm, respectively.See Supplementary materials for details.
The nitro group of molecule M 2 was coplanar with the benzene ring it was attached to (the twist angle was 5.9(3) • ), whereas the group was disordered in M 1 , with twists of approximately 15 • from the plane of the corresponding benzene ring.The triazole and (ethylidene)hydroxylamine groups were coplanar in both molecules, with twist angles M 1 B/M 1 C and M 2 B/M 2 C of 4.38(15) • and 7.77(12) • , respectively.In both molecules, the benzene rings were twisted from the planes of the triazole ring with twist angles of 35.7(1) • and 47.7(1) • .

General
The 1 H (500 MHz) and 13 C NMR (125 MHz) spectra were assessed using a JEOLNMR spectrometer.The chemical shift (δ) was measured in ppm and, the coupling constant (J) was calculated in Hz.Compound 1 was produced based on a literature procedure [36].

Synthesis of 2
A mixture of methyl ketone 1 (0.63 g, 2.5 mmol) and H 2 NOH.HCl (0.35 g, 5.0 mmol) in dry EtOH (15 mL) was refluxed for 5 h.The mixture was left to cool to 20

Crystal Structure Determination
Single-crystal XRD data were collected on an Agilent SuperNova Dual Atlas diffractometer with a mirror monochromator using Mo radiation.The crystal structure of 2 was solved and refined using SHELXT [37] and SHELXL [38].The nitro group of one molecule was disordered with two components related by a 34.1 (11) • twist about the C-N bond with occupancies of 0.52(3) and 0.48(3).Non-hydrogen atoms were refined with anisotropic displacement parameters and hydrogen atoms were inserted in idealized positions; a riding model was used with Uiso set at 1.

Supplementary Materials:
The following are available online. 1

Figure 1 .
Figure 1.An ORTEP representation of the asymmetric unit of 2 showing 50% probability atomic displacement parameters.

Figure 2 .
Figure 2. (a): Crystal packing and (b): a segment of the structure showing hydrogen bonding as blue dotted lines.
• C and the solid produced was collected via filtration.The product was washed with EtOH, dried, and recrystallized from DMF to yield 2 in crystalline form in 86% yield.MP 212-213 • C.