All Notebooks | Help | Support | About
Archives
Authors
Sections
Tools
Show/Hide Keys
29th October 2012 @ 11:03
Synthesis of 2-amino-2-oxoethyl 5-methyl-1-phenyl-1H-pyrazole-4-carboxylate from cyanomethyl 5-methyl-1-phenyl-1H-pyrazole-4-carboxylate.

523.png

Reaction Time: 19-10-2012 (11.25 IST)

Experimental Procedure: To a flask containing cyanomethyl 5-methyl-1-phenyl-1H-pyrazole-4-carboxylate (300 mg, 1.2 mmol, 1equiv) was added 3.0 mL of TFA:H2SO4 (4:1, v/v) and the mixture was stirred vigorously at room temperature. Within 5 min, TLC showed complete consumption of the starting material. The reaction mixture was diluted with ice water (10 mL) and extracted with EtOAc (3X10 mL). The combined organic layers were washed with saturated Na2CO3 solution, and then with brine (20 mL), dried with anhydrous Na2SO4 and concentrated under reduced pressure to afford a residue which was purified by column chromatography (EtOAc/hexanes, 80:20, v/v) to afford an off white solid (264 mg, 82 %).

A melting point of the pure product: 124 – 125 oC.

TLC after 5 min (ethyl acetate) visualised using UV :
2012-10-25 16.28.18.jpg


[b]1 NMR Spectra
SBHK-523-H1.jpg
Linked Posts
This post is linked by:
Attached Files
29th October 2012 @ 10:31
Synthesis of cyanomethyl 5-methyl-1-phenyl-1H-pyrazole-4-carboxylate from 5-methyl-1-phenyl-1H-pyrazole-4-carboxylic acid and bromoacetonitrile.

516.png


Reaction Time: 18-10-2012 (10.55 IST)

Experimental Procedure: A mixture of 5-methyl-1-phenyl-1H-pyrazole-4-carboxylic acid(300 mg, 1.5 mmol, 1equiv) and K2CO3 (137 mg, 1.0 mmol, 0.7 equiv) was taken in 15 mL of acetone and was stirred for 30 min. Then bromoacetonitrile (100 mg, 1.5 mmol, 1.0 equiv) was added and reaction was continued under heating at reflux. After 8 h, TLC showed complete consumption of the starting material. The reaction mixture was evaporated and to it was added water (20 mL) and the product was extracted with EtOAc (3 X 10 mL). The combined organic layer was washed with brine (15 mL), dried with anhydrous Na2SO4 and concentrated under reduced pressure to afford the crude product. Purification by column chromatography on silica gel (EtOAc/hexanes, 40:60, v/v) afforded pure product as colourless oil (359 mg, 90 %).

TLC after 8 hour (ethyl acetate) visualised using UV :
2012-10-25 16.36.59.jpg


1NMR Spectra :
SBHK-516-H1pA.jpg
Attached Files
4th October 2012 @ 08:12
Synthesis of ethyl 5-methyl-1-phenyl-1H-pyrazole-4-carboxylic acid by basic hydrolysis

5-methylpyrazoleacid.png


Reaction Time: 26-08-2012 (10.25 IST)

Experimental Procedure: Ethyl 5-methyl-1-phenyl-1H-pyrazole-4-carboxylate (1.00 g, 4.3 mmol, 1.0 equiv), yellowish oil , was dissolved in a THF/water (20 mL, 1:1, v/v) mixture at room temperature and left for stirring overnight at room temperature. Even after 16 hours TLC showed no reaction. The mixture was then refluxed at 80 oC, after 45 min TLC showed product formation but starting material remained, so reaction mixture was continued to reflux. After 6 hours TLC showed complete consumption of the starting material. The reaction mixture was cooled to room temperature and then to 0 oC and acidified (pH 1) with 6M HCl. The reaction mixture was diluted with EtOAc (10 mL) and extracted with EtOAc (3X10 mL). The combined organic layers were washed with brine (20 mL), dried with anhydrous Na2SO4 and concentrated under reduced pressure to afford a residue which was subjected to recrystallization in diethylether (15 mL). First crop gave pure product (0.140 g, 0.69 mmol, 16%) as white needles which was used for characterisation. The solvent was removed from mother liquor to give white powder (0.434 g, 2.1 mmol, 50% making 66% in total).

Melting point of the pure product: 195 – 196 oC.

TLC after 22 hour (40% ethyl acetate in hexane) visualised using UV :
2012-10-02 18.59.19.jpg


[b]1 NMR Spectra
SBHK-489-H1.JPG
Linked Posts
This post is linked by:
Attached Files
4th October 2012 @ 07:36
Synthesis of ethyl 5-methyl-1-phenyl-1H-pyrazole-4-carboxylate from ethylacetoacetate, dimethylformamidedimethylacetal and phenylhydrazine.

5-methylpyrazoleester.png


Reaction Time: 24-08-2012 (10.55 IST)

Experimental Procedure: Dimethylformamidedimethylacetal (2.7 mL, 1 equiv, 28 mmol) was added with stirring to ethylacetoacetate (4.5 mL, 1.21 equiv, 34 mmol), the mixture turned yellow then it was heated to reflux for 2 hours at 100 oC. TLC showed consumption of ethylacetoacetate. The generated enamineketone was taken up in ethanol (60 mL) and phenylhydrazine (4.3 mL, 1.21 equiv, 34 mmol) was added to it. The reaction mixture was heated at 80 oC (reflux). After 1 hour TLC showed consumption of phenylhydrazine. The reaction mixture was evaporated under vacuum and to it was added water (50 mL) followed by extraction with EtOAc (3 X 30 mL). The organic layers were combined and washed with brine (40 mL), dried with anhydrous Na2SO4 and concentrated under reduced pressure to afford the crude product which was purified by column chromatography (EtOAc/hexanes, 10:90, v/v) to obtain the product as yellowish oil (5.41, 84 %).


TLC after 2 hour (20% ethyl acetate in hexane) visualised using UV and I2:
2012-08-24 19.17.12.jpg


TLC after 3 hour (20% ethyl acetate in hexane) visualised using UV and I2:
2012-08-24 19.44.40.jpg


1 NMR Spectra:
SBHK-486-H1.JPG
Linked Posts
This post is linked by:
Attached Files