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16th April 2019 @ 20:58

2-chloro-6-(2-hydrazinyl)(2-hydroxybenzylidene)pyrazine was synthesised as an intermediate compound in the overall synthesis of 5-chloro-3-(2-hydroxyphenyl)-[1,2,4]triazolo[4,3-a]pyrazine.

Reagent Mass/g Moles/mmol Equivalents
2-chloro-6-hydrazinopyrazine  0.0523 0.360 1.00
4-carboxybenzaldehyde 0.0560 0.460 1.28

Yield: 86.1%

Procedure

2-chloro-6-hydrazinopyrazine (52.3 mg, 0.36 mmol, 1.0 eq.) and 2-hydroxybenzaldehyde (56.0 mg, 0.46 mmol, 1.28 eq.) were added to a round-bottom flask and dissolved in ethanol (10 mL). The resulting solution was heated to 80 °C under reflux for 75 minutes. The reaction was monitored using TLC with a solvent system of 7: 3 PET ether: EtOAc. Once the reaction had gone to completion, the solution was recrystallised. The minimum amount of boiling water needed to precipitate out the product was added, and the mixture was then cooled to allow the product to crash out. The crystals were filtered under vacuum to give a light-yellow powder. The product was analysed by mass spec, IR, 1H and 13C NMR.

Analytical Data 

mp 228 – 231 °C (from EtOH); RF0.44; nmax/cm-13157 (NH), 1625 (CN), 1563 (NH), 1417 (OH); dH (300 MHz, DMSO-d6): d11.52 (s, 1H, NH), 10.22 (s, 1H, OH), 8.44 (s, 1H, pyrazine C), 8.37 (s, 1H, pyrazine C), 8.03 (s, 1H, N=CH) 7.75-7.72 (d, 1H, J= 9.0 Hz, Ar), 7.25-7.20 (t, 1H, J= 9.0 Hz, Ar), 6.91-6.87 (m, 2H, Ar); dC (75 MHz, DMSO-d6): d156.4 (pyrazine C), 152.3 (pyrazine C), 145.9 (C=N), 141.2 (COH), 132.4 (CCl), 130.9, 129.0 (Ar), 126.9 (Ar), 120.5 (Ar), 119.7 (Ar), 116.4 (Ar); m/z 249.0538 (M+H+).

InChI Key:

2-chloro-6-hydrazinopydrazine: FEDQSVIJHNBUHH-UHFFFAOYSA-N

2-hydroxybenzaldehyde: SMQUZDBALVYZAC-UHFFFAOYSA-N

2-chloro-6-(2-hydrazinyl)(2-hydroxybenzlidene)pyrazine: BTVQPPGRWZUSCA-LHHJGKSTSA-N

Attached Files
2-hydroxybenzaldehyde reaction 1.pdf
1H NMR 2-chloro-6-(2-hydrazinyl)(2-hydroxybenzylidene)pyrazine.png
ESI MS 2-chloro-6-(2-hydrazinyl)(2-hydroxybenzylidene)pyrazine.png
13C NMR 2-chloro-6-(2-hydrazinyl)(2-hydroxybenzylidene)pyrazine.png
IR 2-chloro-6-(2-hydrazinyl)(2-hydroxybenzylidene)pyrazine.png