Tag Archives: Malaria

Synthesis of 5-chloro-3-(2-hydroxyyphenyl)-[1,2,4]triazolo[4,3-a]pyrazine

5-chloro-3-(2-hydroxyphenyl)-[1,2,4]triazolo[4,3-a]pyrazine was synthesised using previously synthesised intermediate 2-chloro-6-(2-hydrazinyl)(2-hydroxybenzylidene)pyrazine.

Reagent Mass/g Moles/mmol Equivalents
2-chloro-6-(2-hydrazinyl)(2-hydroxybenzylidene)pyrazine 0.020 0.080 1.00
diacetoxyiodobenzene 0.0290 0.090 1.13

Yield: 54.3%

Procedure

2-chloro-6-(2-hydrazinyl(2-hydroxybenzylidene)pyrazine (20 mg, 0.080 mmol, 1 eq.) and diacetoxyiodobenzene (29 mg, 0.090 mmol, 1.13 eq.) was dissolved in DCM (10 mL) and left overnight stirring under an atmosphere of nitrogen. The reaction was monitored by TLC using a variety of solvent systems (1:1 PET ether: EtOAc, 1:3 PET ether: EtOAc, 100% EtOAc, 20% MeOH in EtOAc and 1% acetic acid in EtOAc) however the spots did not move off the baseline and so the product was not suitable for purification by column chromatography. The solvent was removed in vacuoto give a dark orange powder which was analysed by mass spec and 1H NMR. Both NMR and mass spec showed that the intended product was not formed.

Analytical Data 

mp 261-264 °C.

InChI Key:

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

PIDA: ZBIKORITPGTTGI-UHFFFAOYSA-N

5-chloro-3-(2-hydroxyyphenyl)-[1,2,4]triazolo[4,3-a]pyrazine: GLKVTIUQXSULMV-UHFFFAOYSA-N

 

Synthesis of 2-chloro-6-(2-hydrazinyl)(4-carboxybenzylidene)pyrazine

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

Synthesis of 5-chloro-3-(4-carboxyphenyl)-[1,2,4]triazolo[4,3-a]pyrazine

Reagent Mass/g Moles/mmol Equivalents
diacetoxyiodobenzene  0.023 0.0714 0.9
2-chloro-6-(2-hydrazinyl(4-carboxybenzylidene))pyrazine 0.022 0.0795 1.0

Yield: 40%

Procedure

PIDA (0.023 g, 0.0714 mmol, 0.9 eq.) was added to a stirred solution of the intermediate pyrazine I1 (0.022 g, 0.0795 mmol, 1 eq.) and DCM (10 mL, 0.157 mol, 2 eq.) at rt under N. The resulting mixture was stirred at rt for 150 min. Then, the solvent was evaporated under reduced pressure to give the crude product. Purification by flash column chromatography on silica with 80:19:1 EtOAc-PET ether-Acetic acid as eluent gave P1 (0.0087 g, 40%) as a light yellow powder

Analytical Data 

mp 269 – 274 °C; RF (80:19:1 EtOAc-PET ether-Acetic acid) 0.26; 1H NMR (300 MHz, CDCl3)

Synthesis of 2-chloro-6-(2-hydrazinyl)(4-carboxybenzylidene)pyrazine

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

Reagent Mass/g Moles/mmol Equivalents
2-chloro-6-hydrazinopyrazine  0.0512 0.354 1.00
4-carboxybenzaldehyde 0.052 0.346 0.98

Yield: 70% 

Procedure

2-chloro-6-hydrazinopyrazine (0.0512 g, 0.354 mmol, 1 eq.) was added to a stirred solution of 4-carboxybenzaldehyde (0.052 g, 0.346 mmol, 0.98 eq.) in EtOH (10 mL) at rt in air. The resulting mixture was stirred and heated at reflux for 75 min. Then, the reaction mixture was allowed to cool to rt. The solution was then dried (MgSO4) and evaporated under reduced pressure to give the crude product. Purification by flash column chromatography on silica with 70:30 PET ether-EtOAc as eluent gave I1 (0.0672 g, 70%) as a yellow crystalline solid.

Analytical Data 

mp 229 – 231 °C; RF (70:30 PET ether-EtOAc) 0.28; 1H NMR (300 MHz, DMSO-d6)

Gastric Acid Stability Test on 5-chloro-3-(2,4-dimethoxyphenyl)-[1,2,4]triazolo[4,3-a]pyrazine

Gastric Acid Stability Test on 5-chloro-3-(2,4-dimethoxyphenyl)-[1,2,4]triazolo[4,3-a]pyrazine

5-chloro-3-(2,4-dimethoxyphenyl)-[1,2,4]triazolo[4,3-a]pyrazine was added to a gastric acid mimic to test its stability.

Risk Assessment:

Procedure:

Stomach acid risk assessment.pdf

A 50 mL standard solution of DCl (0.075 mL, 7 mol dm-3, 0.525 mmol) and KCl (0.1863 g, 2.50 mmol) was made up with D2O. This solution was tested using Litmus paper to ensure that is was approximately pH 2. Each pyrazine product was added to the solution (ca. 2 mL), and a 1H NMR was instantly taken.

Analytical Data: 

Run 1: 

P5 Acid Test run 1.pdf

Run 2:

P5 Acid Test run 1.pdf

Write up:

This product was partially soluble in solution. Run 1 was taken 5 minutes after adding the product to the solution and run 2 was taken 3 hours afterwards. As shown by there being no change in the 1H NMRs, the product remained undegraded.

InChi Key: 

5-chloro-3-(2,4-dimethoxyphenyl)-[1,2,4]triazolo[4,3-a]pyrazine: LPODABXRBQELBM-UHFFFAOYSA-N

Synthesis of 5-chloro-3-(4-nitrophenyl)-[1,2,4]triazolo[4,3-a]pyrazine

Synthesis of final drug analogue using previously syntheised intermediate Synthesis of 2-chloro-6-(2-hydrazinyl)(4-nitrobenzlidene)pyrazine (SM, RM, 1-1)


Risk assessment 

Nitrobenzaldehyde 2nd reaction.pdf

Reaction scheme

Tabulated quantities

  2-chloro-6-(2-hydrazinyl)(4-nitrobenzlidene)pyrazine  PIDA Product
Mass / mg  20.1 31.0   13.1
Moles / mmol 0.0726  0.0963   0.0475
Equivalents  1.00 1.33 


Yield: 65.6%


Procedure 

Diacetoxyiodobenzene (PIDA) (31.0 mg, 0.0963 mmol) and intermediate 2-chloro-6-(2-hydrazinyl)(4-nitrobenzlidene)pyrazine (20.1 mg 0.0726 mmol) were added to a 50 mL round bottomed flask. The flask was evacuated and placed under nitrogen. Dry DCM (10 mL) was then added. The resulting solution was stirred at room temperature until TLC had shown the reaction had gone to completion. The solvent was removed in vacuo.

Analytical data

 

p3 Assigned .pdf
1H NMR

P3 13C (1).pdf
13C NMR

P3 (1).pdf
IR

Intermediate3.pdf
MS

Write up data

Experiemental completed as shown in procedure, reaction time 180 minutes 

InChi keys

PIDA: ZBIKORITPGTTGI-UHFFFAOYSA-N

2-chloro-6-(2-hydrazinyl)(4-nitrobenzlidene)pyrazine: IEHJAFIAPRDGAK-LHHJGKSTSA-N

5-chloro-3-(3-nitrophenyl)-[1,2,4]triazolo[4,3-a]pyrazine: WCCGFMGKEGZANC-UHFFFAOYSA-N

 

Gastric Acid Stability Test on 5-chloro-3-(4-chlorophenyl)-[1,2,4]triazolo[4,3-a]pyrazine

Gastric Acid Stability Test on 5-chloro-3-(4-chlorophenyl)-[1,2,4]triazolo[4,3-a]pyrazine

5-chloro-3-(4-chlorophenyl)-[1,2,4]triazolo[4,3-a]pyrazine was added to a gastric acid mimic to test its stability.

Risk Assessment:

Stomach acid risk assessment.pdf

Procedure:

A 50 mL standard solution of DCl (0.075 mL, 7 mol dm-3, 0.525 mmol) and KCl (0.1863 g, 2.50 mmol) was made up with D2O. This solution was tested using Litmus paper to ensure that is was approximately pH 2. Each pyrazine product was added to the solution (ca. 2 mL), and a 1H NMR was instantly taken.

Analytical Data: 

Run 1:

P4 Acid Test Run 1 Assigned.pdf

Run 2:

P4 Acid Test Run 2 - Assigned.pdf

Write up:

This product was partially soluble in solution. Run 1 was taken 5 minutes after adding the product to the solution and run 2 was taken 3 hours afterwards. As shown by there being no change in the 1H NMRs, the product remained undegraded.

InChi Key:

5-chloro-3-(4-chlorophenyl)-[1,2,4]triazolo[4,3-a]pyrazine: RYOJXLCESFRDHI-UHFFFAOYSA-N

Gastric Acid Stability Test on 5-chloro-3-(3-nitrophenyl)-[1,2,4]triazolo[4,3-a]pyrazine

Gastric Acid Stability Test on 5-chloro-3-(3-nitrophenyl)-[1,2,4]triazolo[4,3-a]pyrazine

5-chloro-3-(3-nitrophenyl)-[1,2,4]triazolo[4,3-a]pyrazine was added to a gastric acid mimic to test its stability.

Risk Assessment: 

Stomach acid risk assessment.pdf

Procedure:

A 50 mL standard solution of DCl (0.075 mL, 7 mol dm-3, 0.525 mmol) and KCl (0.1863 g, 2.50 mmol) was made up with D2O. This solution was tested using Litmus paper to ensure that is was approximately pH 2. Each pyrazine product was added to the solution (ca. 2 mL), and a 1H NMR was instantly taken.

Analytical Data: 

P3 Acid Test.pdf

Write up:

This product did not dissolve in the solution. Further experiments should be completed to test the products stability in solution more similar to the bile.

InChi Key:

5-chloro-3-(3-nitrophenyl)-[1,2,4]triazolo[4,3-a]pyrazine: WCCGFMGKEGZANC-UHFFFAOYSA-N

Gastric Acid Stability Test on 5-chloro-3-(2-hydroxyphenyl)-[1,2,4]triazolo[4,3-a]pyrazine

Gastric Acid Stability Test on 5-chloro-3-(2-hydroxyphenyl)-[1,2,4]triazolo[4,3-a]pyrazine

5-chloro-3-(2-hydroxyphenyl)-[1,2,4]triazolo[4,3-a]pyrazine was added to a gastric acid mimic to test its stability.

Risk Assessment: 

Stomach acid risk assessment.pdf

Procedure:

A 50 mL standard solution of DCl (0.075 mL, 7 mol dm-3, 0.525 mmol) and KCl (0.1863 g, 2.50 mmol) was made up with D2O. This solution was tested using Litmus paper to ensure that is was approximately pH 2. Each pyrazine product was added to the solution (ca. 2 mL), and a 1H NMR was instantly taken.

Analytical Data: 

P2 Acid Test.pdf

Write up:

This product did not dissolve in the solution. Further experiments should be completed to test the products stability in solution more similar to the bile.

InChi Key:

5-chloro-3-(2-hydroxyphenyl)-[1,2,4]triazolo[4,3-a]pyrazine: GZVIZULYDGVDDJ-UHFFFAOYSA-N

Gastric Acid Stability Test on 5-chloro-3-(4-carboxyphenyl)-[1,2,4]triazolo[4,3-a]pyrazine

Gastric Acid Stability Test on 5-chloro-3-(4-carboxyphenyl)-[1,2,4]triazolo[4,3-a]pyrazine

5-chloro-3-(4-carboxyphenyl)-[1,2,4]triazolo[4,3-a]pyrazine was added to a gastric acid mimic to test its stability.

Risk Assessment:

Stomach acid risk assessment.pdf

Procedure:

A 50 mL standard solution of DCl (0.075 mL, 7 mol dm-3, 0.525 mmol) and KCl (0.1863 g, 2.50 mmol) was made up with D2O. This solution was tested using Litmus paper to ensure that is was approximately pH 2. Each pyrazine product was added to the solution (ca. 2 mL), and a 1H NMR was instantly taken.

Analytical Data: 

P1 Acid Test.pdf

Write up:

This product did not dissolve in the solution. Further experiments should be completed to test the products stability in solution more similar to the bile.

InChi Key:

5-chloro-3-(4-carboxyphenyl)-[1,2,4]triazolo[4,3-a]pyrazine: MXFMGDAHAUPHHU-UHFFFAOYSA-N