Tag Archives: Malaria

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




Purification 2-chloro-6-hydrazinopydrazine

Purification of 2-chloro-6-hydrazinopydrazine

2-chloro-6-hydrazinopydrazine was purified using flash chromatography incase it had degraded.

Risk Assessment:

General Solvents Risk Assessment.pdf

Reaction Scheme:

Tabulated Chemicals and Quantities:

Mass of Crude 2-chloro-6-hydrazinopydrazine (g, mmol) Pure 2-chloro-6-hydrazinopydrazine(g, mmol) Yeild (%)
1.006, 6.99 0.549, 3.81 54.6

Procedure:

Crude 2-chloro-6-hydrazinopydrazine (1.006 g, 6.99 mmol, brown clumpy crystals) was purified using flash chromatography on silica with a solvent system of 98% ethyl acetate and 2% triethylamine. The pure product was identified from its decomposed residues using TLC (Rf = 0.34) using the same solvent system. The product was concentrated in vacuo (0.549 g, 3.81 mmol, 54.6%). The pure 2-chloro-6-hydrazinopydrazine yielded orange crystals and was characterised via 1H NMR and IR spectrometry.

Analytical Data:

1H NMR of Crude 2-chloro-6-hydrazinopydrazine:

Crude SM_Jvalues Assigned.pdf

1H NMR of Pure 2-chloro-6-hydrazinopydrazine:

Crude SM_Jvalues Assigned.pdf

Write-up:

There were no deviations from the procedure. Ethyl Acetate and triethylamine were used as a solvent system as the compounds are very polar.

InChi Key: 

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

Synthesis of 2-chloro-6-(2-hydrazinyl)(4-nitrobenzlidene)pyrazine (SM, RM, 1-1)

2-chloro-6-(2-hydrazinyl)(4-nitrobenzlidene)pyrazine was synthesised as one of the intermediates used for the synthesis of the final drug analogues

Risk assesment file attached below

MChem miniproject risk assessment pro-forma Nitro-benzaldehyde.pdf

Reaction scheme

    

  2-chloro-6-hydrazinopydrazine  4-Nitrobenzaldehyde Product
Mass / mg  52.0 55.0   67.3
Moles / mol  0.361 0.364  0.243 
Equivalents 1.00  1.01   /

Yield: 70%

Procedure

2-chloro-6-hydrazinopydrazine (52.0 mg, 0.361 mmol) was added to R-benzaldehyde (55.0mg, 0.364 mmol) and dissolved in ethanol (15 cm3) in a 50 mL round bottomed flask. The solution was put under reflux and monitored using TLC (using a solvent system of 7:3 PET ether:EtOAc) until completion. A solid crashed out throughout the reaction and the solution was found to have no remaining starting material. The solid was filtered and washed with ice cold ethanol (3 x 2 mL). . Each intermediate was characterised via 1H NMR, 13C NMR, IR, ESI MS and melting point. 

Analytical data

I3 C ASSIGNED (1).pdf
13C NMR

Intermediate 3 (4-nitro) DMSO - ASSIGNED.pdf
1H NMR

I3.pdf
IR

Intermediate3 mass spec.pdf
MS

1H NMR (300 MHz, DMSO): 8.66 (1 H, s, N=CH), 8.26 (2 H, d, J = 8.88 Hz, Ph), 8.15 (2 H, d, J = 6.09 Hz, Ph), 8.01 (2 H, d, J = 8.88 Hz, Ph), 3.33 (24 H, s, H2O).

13C NMR (75 MHz, chloroform-d): No resolved peaks.

13C NMR (75 MHz, DMSO): 147.74 (Ph-NO2), 146.03 (N=C), 140.51 (Ph-NH), 133.83 (Ph), 129.63 (Ph), 127.88 (Ph), 124.47 (Ph).

MS (TOF MS ESI+): m/z 278.0439 ([M + H]+).

Write up data 

Experiment undertaken as seen in procedure. This reaction was completed in 60 minutes

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

See files attached for risk assessment: 

24dimethoxybenzaldehyde reaction 2 ring closing.pdf

Reaction scheme for synthesis of 5-chloro-3-(2,4-dimethoxyphenyl)-[1,2,4]triazolo[4,3-a]pyrazine

Reagent Mass/ g Moles/ mmol  Equivalents/ Relative molecular mass / g mol-1
 2-chloro-6-(2-hydrazinyl(2,4-dimethoxy)benzylidene))pyrazine  0.0208  0.071  1.0  292.726
 diacetoxyiodobenzene  0.0771  0.239  3.4  322.094


Procedure

2-chloro-6-(2-hydrazinyl(2,4-dimethoxy)benzylidene))pyrazine (0.0208 g, 0.071 mmol, 1.0 eq.) and diacetoxyiodobenzene (0.0256 g, 0.079 mmol, 1.1 eq.) were dissolved in dry dichloromethane and stirred under nitrogen at room temperature for 5 hours. The reaction was monitored by TLC (solvent system: ethyl acetate/light petroleum (40-60 oC) = 5:5). After 5 hours, TLC showed the presence of some product and unreacted 2-chloro-6-(2-hydrazinyl(2,4 dimethoxy)benzylidene))pyrazine and diacetoxyiodobenzene. The solvent was then removed in vacuo and the solid obtained was dissolved in chloroform (10mL). Diacetoxyiodobenzene (0.0771 g, 0.239 mmol, 3.4 eq.) was added and the mixture was heated to 40 oC under nitrogen with stirring for 1.5 hours. The reaction was monitored by TLC (solvent system: ethyl acetate/light petroleum (40-60 oC) = 5:5). The solvent was removed in vacuo, yielding orange-brown crystals which were then dissolved in chloroform (1 mL) and purified by flash column chromatography on silica gel (eluent: ethyl acetate/light petroleum (40-60 oC) = 5:5). TLC indicated the presence of two products and so the fractions of each product were combined and the solvent removed in vacuo, yielding one brown solid and one white solid. Through examining NMR data, the white solid was concluded to be the desired product, 5-chloro-3-(2,4-dimethoxyphenyl)-[1,2,4]triazolo[4,3-a]pyrazine (0.0131 g, 0.0451 mmol, 63.1 %).

Analytical data

1H NMR (300 MHz; chloroform-d): δ 9.29 (s, 1H, pyrazine), 7.81 (s, 1H, pyrazine), 7.49 (d, J = 9 Hz, 1H, Ar), 6.65 (d, J = 3 Hz, 1H, Ar ), 6.54 (s, 1H, Ar), 3.91 (s, 3H, OMe), 3.72 (s, 3H, OMe)
13C{1H} NMR (75.5 MHz; chloroform-d) δ 163.62 (Ar), 160.01 (Ar), 142.73 (pyrazine CH), 132.96 (Ar), 129.12 (pyrazine CH), 104.37 (Ar), 98.26 (Ar)
ESI-MS m/z 291.0643 ([M+H]+), 313.0463 ([M+Na]+)

InChi Keys
2-chloro-6-(2-hydrazinyl(2,4-dimethoxy)benzylidene))pyrazine: AQDLOVYDRCNOGX-OMCISZLKSA-N
diacetoxyiodobenzene: ZBIKORITPGTTGI-UHFFFAOYSA-N
5-chloro-3-(2,4-dimethoxyphenyl)-[1,2,4]triazolo[4,3-a]pyrazine: ZCUXHWCQYZCFEI-UHFFFAOYSA-N

Synthesis of 2-chloro-6-(2-hydrazinyl(2,4-dimethoxybenzylidene))pyrazine (SH 1-1)

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

See files attached for risk assessment:

24dimethoxybenzaldehyde reaction 1.pdf

Reaction scheme for synthesis of 2-chloro-6-(2-hydrazinyl(2,4-dimethoxybenzylidene))pyrazine

Reagent Mass / mg Moles / mmol Equivalents /  Relative Molecular Mass / g mol-1
2-chloro-6-hydrazinopyridazine 50  0.35  1.0  144.565
2,4-dimethoxybenzaldehyde 60  0.36  1.0  166.176


Procedure

2-chloro-6-hydrazinopyridazine (50 mg, 0.35 mmol, 1.0 eq.) and 2,4-dimethoxybenzaldehyde (60 mg, 0.36 mmol, 1.03 eq.) were dissolved in ethanol (10 mL) and refluxed for 2 hours. The reaction was monitored by TLC (solvent system: ethyl acetate/light petroleum (40-60 oC) = 3:7). A dark yellow solution was formed and upon cooling, a dark orange precipitate was formed. The mixture was filtered and the precipitate was collected and dissolved in a minimum amount of hot ethanol (ca. 4 mL). Upon the addition of a minimum amount of hot water (ca. 2 mL), crystals were precipitated out and the mixture was left to cool. Powder-like, pale yellow crystals were collected via filtration and washed with cold ethanol (ca. 2 mL) ( 42.7 mg, 0.146 mmol, 42.2 %). 

 Analytical data

IR (ATR): 3180 (N-H stretch), 1615 (C=N stretch), 1569 (N-H bend), 1093 (C-O stretch), 836 (C-Cl stretch) cm-1
1H NMR (300 MHz; DMSO-d6): δ 11.35 (s, 1H, NH), 8.50 (s, 1H, Ar), 8.32 (s, 1H, Ar), 7.99 (s, 1H, Ar), 7.86 (d, J = 9 Hz, 1H, Ar), 6.62 (s, 1H, Ar), 6.59 (d, J = 9 Hz, 1H, Ar ), 3.85 (s, 3H, OMe), 3.82 (s, 3H, OMe)
13C{1H} NMR (75.5 MHz; DMSO-d6) δ 162.43 (Ar), 159.06 (Ar), 152.87 (pyrazine C), 146.00 (pyrazine C), 139.03 (C=N imine), 132.12 (pyrazine CH), 129.08 (pyrazine CH), 126.96 (Ar), 115.77 (N=CHC), 106.91 (Ar), 98.64 (Ar), 56.21 (OMe), 55.88 (OMe)
13C{1H} DEPT-90 NMR (75.5 MHz; DMSO-d6) δ  139.03 (C=N imine), 132.12 (pyrazine CH), 129.08 (pyrazine CH), 126.96 (Ar), 106.91 (Ar), 98.64 (Ar) 
13C{1H} DEPT-135 NMR (75.5 MHz; DMSO-d6) δ 139.03 (C=N imine), 132.12 (pyrazine CH), 129.08 (pyrazine CH), 126.96 (Ar), 106.91 (Ar), 98.64 (Ar), 56.21 (OMe), 55.88 (OMe)
ESI-MS m/z 293.0800 ([M+H]+), 315.0617 ([M+Na]+)

InChi Keys
2-chloro-6-hydrazinopyridazine: FEDQSVIJHNBUHH-UHFFFAOYSA-N
2,4-dimethoxybenzaldehyde: LWRSYTXEQUUTKW-UHFFFAOYSA-N
2-chloro-6-(2-hydrazinyl(2,4-dimethoxybenzylidene))pyrazine: AQDLOVYDRCNOGX-OMCISZLKSA-N

Synthesis of 3-oxo-2-(3-(trifluoromethyl)phenyl)pentanenitrile (SGS18-3-1)

This reaction was performed by Heath, Ronan, Francis, Nathan, Jonah, Oliver, Daniel, Stuart, Jacky and Erin.

Synthesis of 18-3-1

3-(Trifluoromethyl)phenylacetonitrile (11.4g, 0.0617 mol) was added to ethyl propanoate (5.35 g, 0.0524 mol) and THF (100 mL). Potassium tert-butoxide (17.0 g, 0.152 mol) was added with stirring. The reaction mixture immediately turned red and warmed. The reaction was then placed in a water bath and the temperature maintained at 40°C with stirring for 7 h. The potassium tert-butoxide dissolved after 30 min of stirring.

HCl (80 mL, 1 M) was added to stop the reaction, then DCM (60 mL) was added. The intense red organic layer was collected, and the aqueous layer extracted with DCM (30 mL x 2). The organic layer was dried over sodium sulfate and then filtered.

A TLC was run in 25:75 EtOAc:hex, and showed that the crude mixture contains some starting material and two coloured spots. This is consistent with the expected keto and enol tautomers.

 

TLC 75:25 hexane:EtOAc