13808-64-5

Usage

Uses

Used in Chemical Synthesis:
4-Bromo-3-methylpyrazole is used as a synthetic intermediate for the preparation of various chemical compounds. Its unique structure allows for further functionalization and incorporation into more complex molecules, making it a valuable building block in the synthesis of pharmaceuticals, agrochemicals, and other specialty chemicals.
Used in Pharmaceutical Industry:
4-Bromo-3-methylpyrazole is used as a key intermediate in the preparation of substituted piperidines. These substituted piperidines are potent, selective, and capable of penetrating the central nervous system (CNS). They act as α4β2 nicotinic acetylcholine receptor potentiators, which have potential therapeutic applications in the treatment of neurological disorders such as Alzheimer's disease, schizophrenia, and epilepsy.
Additionally, 4-Bromo-3-methylpyrazole is utilized in the synthesis of small molecular B2 receptor antagonists. These antagonists have potential applications in the treatment of various conditions, including inflammation, pain, and cardiovascular diseases, by blocking the action of certain receptors in the body.

InChI:InChI=1/C4H5BrN2/c1-3-4(5)2-6-7-3/h2H,1H3,(H,6,7)

Synthetic route

4-bromo-3-methyl-1-phenylsulphonylpyrazole (130874-31-6) → 4-bromo-3-methyl-1H-pyrazole (13808-64-5)

Conditions	Yield
With potassium hydroxide In methanol for 1h; Heating;	83%
With potassium hydroxide In methanol for 1h; Heating; other 4-bromo-1-phenylsulphonylpyrazoles;	83%

3-Methylpyrazole (1453-58-3) → 4-bromo-3-methyl-1H-pyrazole (13808-64-5)

Conditions	Yield
Stage #1: 3-Methylpyrazole With N-Bromosuccinimide In N,N-dimethyl-formamide at 60℃; Continuous flow reactor; Stage #2: With water; acetic acid In N,N-dimethyl-formamide	49%

3(resp. 5)-methyl-pyrazole → 4-bromo-3-methyl-1H-pyrazole (13808-64-5)

Conditions	Yield
With water; bromine

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + di-tert-butyl dicarbonate (24424-99-5) → tert-butyl 4-bromo-3-methyl-1H-pyrazole-1-carboxylate (1021919-24-3)

Conditions	Yield
With sodium hydroxide In 1,4-dioxane at 20℃;	100%
With sodium carbonate In dichloromethane; water for 2.5h;
With sodium carbonate In dichloromethane at 20℃; for 16h;
With dmap; triethylamine In acetonitrile at 20℃;	0.32 g

3,7-dihydro-1,3,7-trimethyl-1H-purine-2,6-dione (58-08-2) + 4-bromo-3-methyl-1H-pyrazole (13808-64-5) → 4,5,8-tris(4-bromo-3-methyl-1H-pyrazol-1-yl)-1,3,7-trimethyl-3,4,5,7-tetrahydro-1H-purine-2,6-dione

Conditions	Yield
With tetrabutylammonium tetrafluoroborate In acetonitrile at 45℃; for 10h; Inert atmosphere; Electrochemical reaction; Green chemistry; diastereoselective reaction;	99%

9-borabicyclo[3.3.1]nonane dimer (21205-91-4) + 4-bromo-3-methyl-1H-pyrazole (13808-64-5) + potassium hydride → potassium[bis(3-Me-4-Br-pyrazolyl)borate(C8H14)]

Conditions	Yield
In toluene for 3h; Inert atmosphere; Schlenk technique; Reflux;	96%

4-oxanyl methanesulfonate (134419-59-3) + 4-bromo-3-methyl-1H-pyrazole (13808-64-5) → 4-bromo-3-methyl-1-(tetrahydro-2H-pyran-4-yl)-1H-pyrazole

Conditions	Yield
With caesium carbonate In N,N-dimethyl-formamide at 100℃; for 10h;	88%

triisopropylsilyl chloride (13154-24-0) + 4-bromo-3-methyl-1H-pyrazole (13808-64-5) → 4-bromo-3-methyl-1-(triisopropylsilyl)-1H-pyrazole

Conditions	Yield
With triethylamine In dichloromethane for 72h; Reflux;	86.1%

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + carbon dioxide (124-38-9) + methyl iodide (74-88-4) → methyl 4-bromo-3-methyl-1H-pyrazole-1-carboxylate (1207853-38-0)

Conditions	Yield
Stage #1: 4-bromo-3-methyl-1H-pyrazole; carbon dioxide With cesium hydroxide; (hydroxido){N,N'-bis(2,6-diisopropylphenyl)imidazol-2-ylidene}copper(I) In tetrahydrofuran at 40℃; under 1125.11 Torr; for 0.204167h; Inert atmosphere; Stage #2: methyl iodide In tetrahydrofuran Inert atmosphere; regioselective reaction;	85%

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + phenylboronic acid (98-80-6) → 3-Methyl-4-phenyl-1H-pyrazole (13788-84-6)

Conditions	Yield
With palladium diacetate; potassium carbonate; catacxium A In 1,4-dioxane; water at 100℃; for 12h; Inert atmosphere;	84%

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + 1,3,5-trimethyl-benzene (108-67-8) → 4-bromo-1-mesityl-3-methyl-1H-pyrazole

Conditions	Yield
With C24H42N3(1+)*ClO4(1-); lithium perchlorate; acetic acid In acetonitrile at 20℃; for 72h; Electrochemical reaction; Sealed tube; Irradiation;	83%

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + benzenesulfonyl chloride (98-09-9) → 4-bromo-3-methyl-1-phenylsulphonylpyrazole (130874-31-6)

Conditions	Yield
With pyridine for 2h; Heating;	82%

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + phenylboronic acid (98-80-6) → 4-bromo-3-methyl-1-phenyl-1H-pyrazole (50877-45-7)

Conditions	Yield
With pyridine; oxygen; copper diacetate In dichloromethane at 20℃; for 24h;	82%

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + dimethylamino sulfonyl chloride (13360-57-1) → 4-bromo-3-methyl-pyrazole-1-sulphonic acid dimethylamide (882689-55-6)

Conditions	Yield
With 1,4-diaza-bicyclo[2.2.2]octane In acetonitrile at 20℃; for 6h;	81%
With 1,4-diaza-bicyclo[2.2.2]octane In acetonitrile at 20℃; for 6h;	81%
Stage #1: 4-bromo-3-methyl-1H-pyrazole With sodium hydride In N,N-dimethyl-formamide; mineral oil at 0℃; for 0.5h; Stage #2: dimethylamino sulfonyl chloride In N,N-dimethyl-formamide; mineral oil at 0 - 20℃;	54%
Stage #1: 4-bromo-3-methyl-1H-pyrazole With potassium tert-butylate In tetrahydrofuran at 20℃; for 0.333333h; Stage #2: dimethylamino sulfonyl chloride In tetrahydrofuran
Stage #1: 4-bromo-3-methyl-1H-pyrazole With sodium hydride In N,N-dimethyl-formamide at 0 - 20℃; for 1.25h; Stage #2: dimethylamino sulfonyl chloride In N,N-dimethyl-formamide at 0 - 20℃; for 3.25h;

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + benzyl bromide (100-39-0) → 1-benzyl-4-bromo-3-methyl-1H-pyrazole

Conditions	Yield
Stage #1: 4-bromo-3-methyl-1H-pyrazole With sodium hydride In N,N-dimethyl-formamide; mineral oil at 20℃; for 0.5h; Inert atmosphere; Stage #2: benzyl bromide In N,N-dimethyl-formamide; mineral oil at 0 - 20℃;	80%
Stage #1: 4-bromo-3-methyl-1H-pyrazole With sodium hydride In tetrahydrofuran at 0℃; for 0.5h; Stage #2: benzyl bromide In tetrahydrofuran at 0 - 15℃; for 1h;	60%
Stage #1: 4-bromo-3-methyl-1H-pyrazole With sodium hydride In tetrahydrofuran at 0℃; for 0.5h; Stage #2: benzyl bromide In tetrahydrofuran at 0 - 15℃; for 1h;	60%

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + 4-methoxy-phenol (150-76-5) → 2-(4-bromo-3-methyl-1H-pyrazol-1-yl)-4-methoxyphenol

Conditions	Yield
With dipotassium peroxodisulfate In acetonitrile at 80℃; for 5h; Inert atmosphere; Schlenk technique;	76%

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + [Ru(2,2′-bipyridine-6,6′-dicarboxylate)((CH3)2SO)2] (1357927-37-7) → [Ru(2,2′-bipyridine-6,6′-dicarboxylate)(DMSO)(4-bromo-3-methyl-pyrazole)2]

Conditions	Yield
In methanol for 0.333333h; Reflux; Inert atmosphere;	75%

3-bromomethyl-3-methyloxetane (78385-26-9) + 4-bromo-3-methyl-1H-pyrazole (13808-64-5) → 4-bromo-3-methyl-1-((3-methyloxetan-3-yl)methyl)-1H-pyrazole

Conditions	Yield
With caesium carbonate In N,N-dimethyl-formamide at 100℃; for 1.5h; Microwave irradiation;	74.9%

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + trityl chloride (76-83-5) → 4-bromo-3-methyl-1-trityl-1H-pyrazole (474706-49-5)

Conditions	Yield
With triethylamine In chloroform at 20℃; Inert atmosphere;	73%

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + 2-(4-bromo-3-methyl-1H-pyrazol-1-yl)-4-methoxyphenol → 2,6-bis(4-bromo-3-methyl-1H-pyrazol-1-yl)-4-methoxyphenol

Conditions	Yield
With dipotassium peroxodisulfate In acetonitrile at 80℃; for 5h; Inert atmosphere; Schlenk technique;	72%

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + 2,2,2-trifluoroethyl trifluoromethanesulphonate (6226-25-1) → 4-bromo-3-methyl-1-(2,2,2-trifluoroethyl)-1H-pyrazole

Conditions	Yield
With caesium carbonate In N,N-dimethyl-formamide at 100℃; for 0.5h; Microwave irradiation;	68.4%

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + ethyl bromoacetate (105-36-2) → ethyl 2-(4-bromo-3-methyl-1H-pyrazol-1-yl)acetate

Conditions	Yield
With sodium hydride; potassium iodide In N,N-dimethyl-formamide; mineral oil at 80℃; for 12h;	68%

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + [Ru(2,2′-bipyridine-6,6′-dicarboxylate)((CH3)2SO)2] (1357927-37-7) → [Ru(2,2′-bipyridine-6,6′-dicarboxylate)(4-bromo-3-methyl-pyrazole)3]

Conditions	Yield
In methanol for 6h; Reflux; Inert atmosphere;	68%

1-methyl-2(1H)-quinoxalinone (6479-18-1) + 4-bromo-3-methyl-1H-pyrazole (13808-64-5) → 3-(4-bromo-3-methyl-1H-pyrazol-1-yl)-1-methylquinoxalin-2(1H)-one

Conditions	Yield
With air In acetonitrile at 20℃; for 20h; Irradiation;	60%

2-iodo-propane (75-30-9) + 4-bromo-3-methyl-1H-pyrazole (13808-64-5) → 4-bromo-1-isopropyl-3-methyl-1H-pyrazole (1215295-87-6)

Conditions	Yield
With caesium carbonate In acetonitrile at 90℃; for 12h;	56%
With caesium carbonate In acetonitrile at 90℃; for 12h;	56%

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + 1-(tert-butoxycarbonyl)piperidin-4-yl methanesulfonate (141699-59-4) → tert-butyl 4-(4-bromo-5-methyl-1H-pyrazol-1-yl)piperidine-1-carboxylate (1076223-99-8) + tert-butyl 4-(4-bromo-3-methyl-1H-pyrazol-1-yl)piperidine-1-carboxylate (1092500-89-4)

Conditions	Yield
With sodium hydride In mineral oil at 70℃;	A 27% B 53%
With sodium hydride In N,N-dimethyl acetamide; mineral oil at 70℃;	A 27% B 53%
Stage #1: 4-bromo-3-methyl-1H-pyrazole With sodium hydride In N,N-dimethyl-formamide at 0℃; for 1h; Stage #2: 1-(tert-butoxycarbonyl)piperidin-4-yl methanesulfonate In N,N-dimethyl-formamide at 95℃; for 1h;
Stage #1: 4-bromo-3-methyl-1H-pyrazole With sodium hydride In N,N-dimethyl-formamide; mineral oil at 0℃; for 1h; Stage #2: 1-(tert-butoxycarbonyl)piperidin-4-yl methanesulfonate In N,N-dimethyl-formamide; mineral oil at 90℃; for 4h;

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + 1-Chloro-4-fluorobenzene (352-33-0) → 4-bromo-1-(4-chlorophenyl)-3-methyl-1H-pyrazole

Conditions	Yield
With tetrabutylammonium tetrafluoroborate; acetic acid; 2,3-dicyano-5,6-dichloro-p-benzoquinone In acetonitrile at 20℃; for 36h; Sealed tube; Inert atmosphere; Irradiation; Electrolysis;	52%

2-bromo-5-methyl-1,3-thiazole (41731-23-1) + 4-bromo-3-methyl-1H-pyrazole (13808-64-5) → C8H8BrN3S

Conditions	Yield
Stage #1: 4-bromo-3-methyl-1H-pyrazole With sodium hydride In N,N-dimethyl-formamide at 20℃; for 0.5h; Stage #2: 2-bromo-5-methyl-1,3-thiazole In N,N-dimethyl-formamide at 20 - 90℃;	50%

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + 4-bromo-2-(n-propyl)pyridine (98420-99-6) → 4-(4-bromo-3-methyl-1H-pyrazol-1-yl)-2-propylpyridine

Conditions	Yield
With copper(l) iodide; caesium carbonate In N,N-dimethyl acetamide at 1140℃; for 6h; Sealed tube;	49%

4-bromo-3-methyl-1H-pyrazole (13808-64-5) + (2-trimethylethylsilylethoxy)methyl chloride (76513-69-4) → 2-[(4-bromo-3-methylpyrazol-1-yl)methoxy]ethyltrimethylsilane

Conditions	Yield
Stage #1: 4-bromo-3-methyl-1H-pyrazole With sodium hydride In tetrahydrofuran at 0℃; for 0.5h; Stage #2: (2-trimethylethylsilylethoxy)methyl chloride In tetrahydrofuran at 25℃; for 4h;	44.22%

2-bromo-1,3-thiazole (3034-53-5) + 4-bromo-3-methyl-1H-pyrazole (13808-64-5) → C7H6BrN3S

Conditions	Yield
Stage #1: 4-bromo-3-methyl-1H-pyrazole With sodium hydride In N,N-dimethyl-formamide at 20℃; for 0.5h; Stage #2: 2-bromo-1,3-thiazole In N,N-dimethyl-formamide at 20 - 90℃;	42%

Upstream product

• 1453-58-3 3-Methylpyrazole 
• 130874-31-6 4-bromo-3-methyl-1-phenylsulphonylpyrazole 

Downstream Products

• 5775-82-6 4-bromo-1,3-dimethyl-1H-pyrazole 
• 5775-86-0 4-bromo-1,5-dimethyl-1H-pyrazole 
• 5932-19-4 3,4-dibromo-5-methylpyrazole 
• 5334-39-4 3-methyl-4-nitro-1H-pyrazole 
• 120594-15-2 3,3'-dimethyl-4,4'-dibromo-1,1'-bis-pyrazolyl-para-chlorophenylmethane 
• 120594-16-3 3,5'-dimethyl-4,4'-dibromo-1,1'-bis-pyrazolyl-para-chlorophenylmethane 
• 120594-13-0 3,3'-dimethyl-4,4'-dibromo-1,1'-bis-pyrazolyl-ortho-chlorophenylmethane 
• 120594-14-1 3,5'-dimethyl-4,4'-dibromo-1,1'-bis-pyrazolyl-ortho-chlorophenylmethane 
• 105873-92-5 3,3'-dimethyl-4,4'-dibromo-1,1'-bispyrazolylphenylmethane 
• 105873-93-6 3,5'-dimethyl-4,4'-dibromo-1,1'-bispyrazolylphenylmethane 
• 130874-31-6 4-bromo-3-methyl-1-phenylsulphonylpyrazole 
• 1268613-69-9 C₁₃H₁₃BrN₂O 
• 1453-58-3 3-Methylpyrazole 
• 1092563-68-2 tert-butyl 4-(3-methyl-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazol-1-yl)piperidine-1-carboxylate 

Relevant academic research and scientific papers

Facile, fast and safe process development of nitration and bromination reactions using continuous flow reactors

Chemists working in a pilot plant often face safety issues during scale-up operations. With the help of emerging microfluidic applications and microdevices, running hazardous, highly exothermic or potentially unstable reactions can be easily transposed into a safe continuous flow mode. This paper describes how a potentially hazardous pyrazole nitration and the bromination of a variety of electron-rich heteroaromatic substrates were efficiently performed using a cheap and easily available system for bench chemists. Advantages of the continuous flow mode in organic synthetic chemistry will be exemplified by the large-scale production of raw materials under safe, green and reproducible conditions.

Pyrazole Chemistry. Part 4. Directed Lithiation of 4-Bromo-1-phenylsulphonylpyrazole: a Convenient Approach to Vicinally Disubstituted Pyrazoles

4-Bromo-1-phenylsulphonylpyrazole (10), obtained from 4-bromopyrazole (5) and benzenesulphonyl chloride, can be metallated regioselectively by phenyl-lithium to give the 5-lithio derivative (15) which upon quenching with appropriate electrophiles leads to the 4-bromo-1-phenylsulphonyl-5-substituted pyrazoles (16)-(23), (25), and (26).Compounds (22), (23), and (25) were found to undergo isomerisation to afford the thermodynamically more stable 4-bromo-1-phenylsulphonyl-3-substituted pyrazoles (11), (24), and (13) under the reaction conditions applied.The phenylsulphonyl protecting group then can be removed readily under alkaline conditions to yield the corresponding 4-bromo-3(5)-substituted 1H-pyrazoles (6), (9), (28), (29), and (30).