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[ CAS No. 55676-21-6 ]

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Chemical Structure| 55676-21-6
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CAS No. :55676-21-6 MDL No. :MFCD03840751
Formula : C7H6ClNO Boiling Point : -
Linear Structure Formula :- InChI Key :N/A
M.W :155.58 g/mol Pubchem ID :10942697
Synonyms :

Safety of [ 55676-21-6 ]

Signal Word:Warning Class:N/A
Precautionary Statements:P261-P305+P351+P338 UN#:N/A
Hazard Statements:H302-H315-H319-H335 Packing Group:N/A
GHS Pictogram:

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  • Upstream synthesis route of [ 55676-21-6 ]
  • Downstream synthetic route of [ 55676-21-6 ]

[ 55676-21-6 ] Synthesis Path-Upstream   1~24

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Reference: [1] Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry (1972-1999), 1990, # 9, p. 2409 - 2415
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YieldReaction ConditionsOperation in experiment
81% With chromium(VI) oxide In acetone at -30 - 20℃; for 3 h; Step 2:
1-(2-Chloropyridin-3-yl)ethanone
A solution of 1-(2-chloropyridin-3-yl)ethanone (10 g, 0.0635 mol) in dry acetone (200 mL) was introduced under argon into a 1 L flask.
The mixture was cooled to -30° C. and pure, pulverized chromic anhydride (19 g, 0.19 mol) was added.
The reaction mixture was kept at room temperature for 3 h. 2-Propanol (100 mL) was added, followed by aqueous sodium hydrogen carbonate to pH 8.
After filtration, solids were washed with chloroform.
The organic and aqueous layers were then separated and the aqueous layer was extracted with chloroform (2*100 mL).
The combined organics were dried over anhydrous sodium sulfate and evaporated to yield the crude pyridyl ketone as an oil.
This product was purified by column chromatography (8 g, 81percent).
*1H NMR (CDCl3) 8.44 (dd, J=5 and 2 Hz, 1H) 7.91 (dd, J=7.5 and 2 Hz, 1H), 7.34 (dd, J=7.5 and 5 Hz, 1H), 2.68 (s, 3H).
81% With chromium(VI) oxide In acetone at -30 - 20℃; for 3 h; Inert atmosphere Step 2: l-(2-Chloropyridin-3-yl)ethanone.A solution of l-(2-chloropyridin-3-yl)ethanone (1O g, 0.0635 mol) in dry acetone (200 mL) was introduced under argon into a 1 L flask. The mixture was cooled to -30 0C and pure, pulverized chromic anhydride (19 g, 0.19 mol) was added. The reaction mixture was kept at room temperature for 3 h. 2-Propanol (100 mL) was added, followed by aqueous sodium hydrogen carbonate to pH 8. After filtration, solids were washed with chloroform. The organic and aqueous layers were then separated and the aqueous layer was extracted with chloroform (2x10OmL). The combined organics were dried over anhydrous sodium sulfate and evaporated to yield the crude pyridyl ketone as an oil. This product was purified by column chromatography (8 g, 81percent). *1H NMR (CDCl3) 8.44 (dd, J = 5 and 2 Hz, 1 H) 7.91 (dd, J = 7.5 and 2 Hz, 1 H), 7.34 (dd, J = 7.5 and 5 Hz, 1 H), 2.68 (s, 3 H).
77% With chromium(VI) oxide In acetone at -30 - 20℃; for 3.25 h; Inert atmosphere Step 2[00176] To a solution of l-(2-chloropyridin-3-yl)ethanol (II) in dry acetone at - 30°C under nitrogen was added in portions chromium (VI) oxide (1.80 g, 18 mmol). The solution was further stirred 15 min at -30°C and allowed to warm to room temperature. The solution was stirred for 3 h at room temperature before adding isopropanol (10 mL). The solution was made alkaline by slowly adding a saturated NaHC03 solution. The solution was filtered through a bed of Celite. The solids were washed by DCM. The organic phase of the filtrate was separated and the aqueous phase extracted with DCM (2 x 50 mL). The combined organic layers were dried over MgS04, filtered and concentrated under reduced pressure to yield l-(2-chloropyridin-3-yl)ethanone (III) as a brown liquid (0.72 g, 4.63 mmol, 77percent yield). 1H NMR (CDC13) δ ppm 2.71 (s, 3 H), 7.35 (dd, J=7.63, 4.80 Hz, 1 H), 7.91 (dd, J=7.54, 1.88 Hz, 1 H), 8.55 (dd, J=4.71, 1.88 Hz, 1 H).
77% With chromium(VI) oxide In acetone at -30 - 20℃; for 3.25 h; Inert atmosphere To a solution of 1-(2-chloropyridin-3-yl)ethanol (XII) in dry acetone at −30° C. under nitrogen was added in portions chromium (VI) oxide (1.80 g, 18 mmol). The solution was further stirred 15 min at −30° C. and allowed to warm to room temperature. The solution was stirred for 3 h at room temperature before adding isopropanol (10 mL). The solution was made alkaline by slowly adding a saturated aqueous NaHCO3 solution. The solution was filtered through a bed of Celite. The solids were washed by DCM. The organic phase of the filtrate was separated and the aqueous phase extracted with DCM (2×50 mL). The combined organic layers were dried over MgSO4, filtered and concentrated under reduced pressure to yield 1-(2-chloropyridin-3-yl)ethanone (XIII) as a brown liquid (0.72 g, 4.63 mmol, 77percent yield). 1H NMR (CDCl3) δ ppm 2.71 (s, 3H), 7.35 (dd, J=7.63 Hz, J=4.80 Hz, 1H), 7.91 (dd, J=7.54 Hz, J=1.88 Hz, 1H), 8.55 (dd, J=4.71 Hz, J=1.88 Hz, 1H).
77% With chromium(VI) oxide In acetone at -30 - 20℃; for 3.25 h; Inert atmosphere Step 2
To a solution of 1-(2-chloropyridin-3-yl)ethanol (X) in dry acetone at -30° C. under nitrogen was added in portions chromium (VI) oxide (1.80 g, 18 mmol).
The solution was further stirred 15 min at -30° C. and allowed to warm to room temperature.
The solution was stirred for 3 h at room temperature before adding isopropanol (10 mL).
The solution was made alkaline by slowly adding a saturated aqueous NaHCO3 solution.
The solution was filtered through a bed of Celite.
The solids were washed by DCM.
The organic phase of the filtrate was separated and the aqueous phase extracted with DCM (2*50 mL).
The combined organic layers were dried over MgSO4, filtered and concentrated under reduced pressure to yield 1-(2-chloropyridin-3-yl)ethanone (XI) as a brown liquid (0.72 g, 4.63 mmol, 77percent yield).
1H NMR (CDCl3) δ ppm 2.71 (s, 3H), 7.35 (dd, J=7.63 Hz, J=4.80 Hz, 1H), 7.91 (dd, J=7.54 Hz, J=1.88 Hz, 1H), 8.55 (dd, J=4.71 Hz, J=1.88 Hz, 1H).
77% With chromium(VI) oxide In acetone at -30 - 20℃; for 3.25 h; To a solution of 1-(2-chloropyridin-3-yl)ethanol (X) in dry acetone at -30°C under nitrogen was added in portions chromium (VI) oxide (1.80 g, 18 mmol). The solution was further stirred 15 min at -30°C and allowed to warm to room temperature. The solution was stirred for 3 h at room temperature before adding isopropanol (10 mL). The solution was made alkaline by slowly adding a saturated aqueous NaHCCb solution. The solution was filtered through a bed of Celite. The solids were washed by DCM. The organic phase of the filtrate was separated and the aqueous phase extracted with DCM (2 x 50 mL). The combined organic layers were dried over MgSO4, filtered and concentrated under reduced pressure to yield 1 -(2-chloropyridin-3 -yl)ethanone (XI) as a brown liquid (0.72 g, 4.63 mmol, 77percent yield). 1H NMR (CDCl3) δ ppm 2.71 (s, 3H), 7.35 (dd, J=7.63Hz, J=4.80Hz, 1H), 7.91 (dd, J=7.54Hz, J=1.88Hz, 1H), 8.55 (dd, J=4.71Hz, J=1.88Hz, 1H).

Reference: [1] Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry (1972-1999), 1990, # 9, p. 2409 - 2415
[2] Patent: US2006/47126, 2006, A1, . Location in patent: Page/Page column 30
[3] Patent: WO2011/5759, 2011, A2, . Location in patent: Page/Page column 77
[4] Patent: WO2011/84486, 2011, A1, . Location in patent: Page/Page column 106; 110-111
[5] Patent: US2013/296302, 2013, A1, . Location in patent: Paragraph 0494
[6] Patent: US2016/68550, 2016, A1, . Location in patent: Paragraph 1056
[7] Patent: WO2016/40193, 2016, A1, . Location in patent: Paragraph 0703
[8] Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry (1972-1999), 1990, # 9, p. 2409 - 2415
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YieldReaction ConditionsOperation in experiment
72%
Stage #1: at 0℃; for 1 h;
Stage #2: With water In tetrahydrofuran
A solution of 2-chloro-N-methoxy-N-methyl-nicotinamide (23.6 g, 118 mmol) in tetrahydrofuran (350 mL, 0.34M) at 0° C. was treated dropwise via an addition funnel with methyl magnesium chloride (3.0M solution in tetrahydrofuran, 100 mL, 300 mmol).
The reaction became a very thick opaque white mixture and was diluted with additional tetrahydrofuran (150 mL).
The reaction was stirred at 0° C. for 1 h.
At this time, the reaction was carefully quenched with water (250 mL) and then partitioned between additional water (250 mL) and ethyl acetate (250 mL).
The aqueous layer was back extracted with ethyl acetate (2*250 mL).
The combined organics were washed with a saturated aqueous sodium chloride solution (250 mL), dried over magnesium sulfate, filtered, rinsed with ethyl acetate, and concentrated in vacuo.
Flash chromatography (AnaLogix Intelliflash 280, 400 g silica gel column, 25-50percent ethyl acetate/hexanes) afforded 1-(2-chloro-pyridin-3-yl)-ethanone (13.17 g, 72percent) as a yellow oil.
Reference: [1] ACS Medicinal Chemistry Letters, 2012, vol. 3, # 9, p. 764 - 768
[2] Patent: US2012/258982, 2012, A1, . Location in patent: Page/Page column 41
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YieldReaction ConditionsOperation in experiment
91%
Stage #1: at 0℃; for 0.5 h; Inert atmosphere
Stage #2: With ammonium chloride In tetrahydrofuranInert atmosphere
General procedure: Methylmagnesium chloride (0.5 M in THF, 8.0 mL, 4.0 mmol) was added to a solution of 2-pyridyl 2-chloropyridine-3-carboxylate (2c, 939 mg, 4.0 mmol) in THF (12 mL) at 0 °C under argon atmosphere. After stirring for 0.5 h, the mixture was quenched with saturated NH4Cl solution (5 mL) and THF was evaporated in vacuo. The mixture was poured into saturated NH4Cl solution (30 mL) and extracted with dichloromethane (3 × 20 mL). The combined organic phases were dried overanhydrous MgSO4, filtered, and concentrated in vacuo. The residue was purified by vacuum distillation using a Kugelrohr apparatus to give 3c (566 mg, 91percent).
Reference: [1] Bulletin of the Korean Chemical Society, 2013, vol. 34, # 4, p. 1253 - 1256
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YieldReaction ConditionsOperation in experiment
90% at 0℃; for 1 h; To a solution of 2 (473 mg, 3.0 mmol) in THF (8 mL) was added phenylethynyllithium, generated from phenylacetylene (306 mg, 3.0 mmol) and methyllithium (1.5 M in Et2O, 2.0 mL, 3.0 mmol) for 0.5 h at 0 C, or methyllithium (1.5 M in Et2O, 2.0 mL, 3.0 mmol) at 0 C. After being stirred for 0.5 h, the mixture was quenched with 0.5 N HCl (5 mL) and THF was evaporated in vacuo. The mixture was poured into 0.1 N HCl (30 mL) and extracted with dichloromethane(3 × 20 mL). The condensed residue was purified by silicagel column chromatography using 30percent EtOAc/n-hexane or vacuum distillation using a Kugelrohr apparatus to give 3a (616 mg, 85percent) and 6 (420 mg, 90percent), respectively.
90% for 0.5 h; Phenylacetylene (306 mg, 3.0 mmol) and methyl lithium (1.5 M in Et2O, 2.0 mL, 3.0 mmol) were reacted at 0 C for 0.5 hour Was added to a solution of compound 2 (473 mg, 3.0 mmol) in THF (8 mL). For 0.5 hours After mixing, the reaction was quenched by the addition of 0.5 N HCl (5 mL) and THF to the mixture and evaporated in vacuo. evaporation The resulting mixture was taken up in 0.1 N HCl (30 mL) and extracted with dichloromethane (3 x 20 mL). The concentrated residue was dissolved in 30percent The residue was purified by silica gel column chromatography using EtOAc / n-hexane as an extraction solvent to obtain Compound 3a (616 mg, 85percent) Respectively. Also, methyllithium (1.5 M in Et2O, 2.0 mL, 3.0 mmol) was added to a solution of compound 2 (473 mg, 3.0 mmol). After mixing for 0.5 h, the reaction was stopped by adding 0.5 N HCl (5 mL) to the mixture THF was evaporated in vacuo. The evaporated mixture was poured into 0.1 N HCl (30 mL) and added with dichloromethane (3 x 20 mL) . The concentrated residue was vacuum distilled using a Kugelrohr distillation column to yield compound 6 (420 mg, 90percent).
Reference: [1] Bulletin of the Korean Chemical Society, 2015, vol. 36, # 7, p. 1908 - 1911
[2] Patent: KR101766414, 2017, B1, . Location in patent: Paragraph 0078; 0079; 0081
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Reference: [1] Tetrahedron, 1992, vol. 48, # 42, p. 9233 - 9236
[2] Patent: WO2006/123145, 2006, A1, . Location in patent: Page/Page column 40
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YieldReaction ConditionsOperation in experiment
72% at 155℃; for 3 h; After diluting the product in step b) with the appropriate amount of dry toluene,Slowly added to the stirred solution of step a) at room temperature.After stirring for 40 min, the solution was concentrated with concentrated HCl (261 g, 2.32 mol).The toluene layer was evaporated and cooled to give a pale yellow solid.To this solid was added DMSO (650 ml) and water (29 ml).The mixture was heated and maintained at 155 ° C for 3 hours and then heated until the reaction solution was cooled and poured into 2.5 L of cold water,A large amount of off-white solid precipitated, filtered and dried.To give 96 g of product 2-chloro-3-acetylpyridine in 72percent yield.
56% With hydrogenchloride; water In dimethyl sulfoxide at 130℃; for 2 h; Water (1.3 mL) was added to a solution of diethyl 2-(2-chloronicotinoyl)malonate (31.7 mmol) in dimethylsulfoxide (50 mL).
The pH of the reaction mixture was added adjusted to 5-6 by the addition of hydrochloric acid and the reaction mixture was heated at 130° C. for 2 h.
The reaction mixture was then quenched with ice water (300 mL) and the aqueous layer was extracted with ethyl acetate (3*50 mL).
The combined organic layers were washed with brine, dried (sodium sulfate), and concentrated.
The residue was purified by chromatography (1/20 ethyl acetate/petroleum ether to provide 1-(2-chloropyridin-3-yl)ethanone in 56percent yield as light yellow oil.
52% With water In dimethyl sulfoxide at 130℃; for 3.5 h; A solution of diethyl 2-(2-chloronicotinoyl)malonate (267 mmol) in dimethylsulfoxide (100 ml) was added dropwise over 1.5 h to a 130° C. solution of water (10 mL) in dimethylsulfoxide (260 mL).
The reaction mixture was maintained at 130° C. for an additional 2 h and was allowed to cool to rt.
The reaction mixture was diluted with cold (0° C.) water (500 mL) and was extracted with ethyl acetate (3*200 mL).
The combined organic layers were washed with brine (5*200 mL), dried (sodium sulfate), and concentrated.
The residue was purified by chromatography (10/1 petroleum ether/ethyl acetate) to provide 1-(2-chloropyridin-3-yl)ethanone 52percent yield as yellow oil.
Reference: [1] Patent: CN106946770, 2017, A, . Location in patent: Paragraph 0070
[2] Patent: US2007/78147, 2007, A1, . Location in patent: Page/Page column 75
[3] Patent: US2007/78147, 2007, A1, . Location in patent: Page/Page column 73
[4] Patent: WO2005/61476, 2005, A2, . Location in patent: Page/Page column 89
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  • [ 2942-59-8 ]
  • [ 75-16-1 ]
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Reference: [1] Journal of Medicinal Chemistry, 2014, vol. 57, # 18, p. 7577 - 7589
[2] Patent: WO2011/79804, 2011, A1, . Location in patent: Page/Page column 24
[3] Patent: US2012/245178, 2012, A1, . Location in patent: Page/Page column 13
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  • [ 2942-59-8 ]
  • [ 79-37-8 ]
  • [ 594-27-4 ]
  • [ 144-55-8 ]
  • [ 55676-21-6 ]
Reference: [1] Patent: US5688795, 1997, A,
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  • [ 75-16-1 ]
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Reference: [1] European Journal of Medicinal Chemistry, 2012, vol. 57, p. 311 - 322
[2] Patent: WO2016/132134, 2016, A1, . Location in patent: Page/Page column 74
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Reference: [1] Organic and Biomolecular Chemistry, 2010, vol. 8, # 22, p. 5166 - 5173
[2] Canadian Journal of Chemistry, 1988, vol. 66, # 3, p. 420-428
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Reference: [1] Journal of Heterocyclic Chemistry, 1999, vol. 36, # 2, p. 445 - 452
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  • [ 55676-21-6 ]
Reference: [1] ACS Medicinal Chemistry Letters, 2012, vol. 3, # 9, p. 764 - 768
[2] Patent: US2012/258982, 2012, A1,
[3] European Journal of Medicinal Chemistry, 2012, vol. 57, p. 311 - 322
[4] Bulletin of the Korean Chemical Society, 2013, vol. 34, # 4, p. 1253 - 1256
[5] Bulletin of the Korean Chemical Society, 2015, vol. 36, # 7, p. 1908 - 1911
[6] Patent: WO2006/123145, 2006, A1,
[7] Patent: WO2016/132134, 2016, A1,
[8] Patent: KR101766414, 2017, B1,
  • 14
  • [ 6602-54-6 ]
  • [ 676-58-4 ]
  • [ 55676-21-6 ]
Reference: [1] Organic and Biomolecular Chemistry, 2010, vol. 8, # 22, p. 5166 - 5173
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  • [ 55676-21-6 ]
Reference: [1] Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry (1972-1999), 1990, # 9, p. 2409 - 2415
[2] Patent: WO2011/5759, 2011, A2,
[3] Patent: WO2011/84486, 2011, A1,
[4] Patent: US2013/296302, 2013, A1,
[5] Patent: US2016/68550, 2016, A1,
[6] Patent: WO2016/40193, 2016, A1,
  • 16
  • [ 6602-54-6 ]
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  • [ 55676-21-6 ]
Reference: [1] Zeitschrift fuer Chemie (Stuttgart, Germany), 1990, vol. 30, # 7, p. 245 - 246
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  • [ 350-03-8 ]
  • [ 55676-21-6 ]
Reference: [1] Canadian Journal of Chemistry, 1988, vol. 66, # 3, p. 420-428
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  • [ 55676-21-6 ]
  • [ 65326-33-2 ]
Reference: [1] Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry (1972-1999), 1990, # 9, p. 2409 - 2415
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  • [ 124-41-4 ]
  • [ 131674-40-3 ]
YieldReaction ConditionsOperation in experiment
53% for 4 h; Inert atmosphere Sodium methoxide (0.065 g, 1.2 mmol) and 1-(2-chloropyridin-3-yl)ethanone (0.063 gm, 0.4 mmol) were stirred in anhydrous methanol (1.5 mL) in a 7 mL vial under a nitrogen atmosphere for 4 hours. The reaction was cooled to room temperature and 0.5 mL of H2O was added. The mixture was concentratedon a rotary evaporator to remove methanol and the resulting aqueous mixture was partitioned between dichloromethane (20 mL) and water (20 mL). The organic layer was dried over anhydrous sodium sulfate and concentrated on a rotary evaporator to provide the crude product as an orange oil (0.032 g, 53percent yield), which was used without further purification. 1H-NMR (CDCl3) δ 8.33 (dd, J = 4.8 and 2.0 Hz, 1H),8.13 (dd, J = 7.5 and 2.0 Hz, 1H), 7.00 (dd, J = 7.5 and 4.8 Hz, 1H), 4.08 (s,3H), 2.67 (s, 3H). MS (ESI+): m/z (M+H)+ = 152.
Reference: [1] Bioorganic and Medicinal Chemistry, 2015, vol. 23, # 17, p. 5352 - 5359
[2] Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry (1972-1999), 1990, # 9, p. 2409 - 2415
[3] Patent: WO2015/187934, 2015, A1, . Location in patent: Paragraph 0218
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YieldReaction ConditionsOperation in experiment
85% With hydrazine In ethanol for 12 h; Heating / reflux Step 3:
3-Methyl-1H-pyrazolo[3,4b]pyridine
A solution of 1-(2-chloropyridin-3-yl)ethanone (22 g, 0.1415 mol) and hydrazine hydrate 98percent (113 g, 2.21 mol) in ethanol (300 mL) was refluxed for 12 h.
About 80percent of the ethanol was distilled off under reduced pressure using a rotary evaporator.
The residue was allowed to come to room temperature.
The precipitated solid was filtered and washed with water.
The product was dried at 90° C. to constant weight (16 g, 85percent) mp 152-154° C. 1H NMR (CDCl3) 8.62 (dd, J=4.5 and 1.4 Hz, 1H), 8.08 (dd, J=8.0 and 1.4 Hz, 1H), 7.15 (dd J=8.0 and 4.5 Hz, 1H), 2.64 (s, 3H). MS (FAB) m/z: 133 (M++1).
85% With hydrazine hydrate In ethanol for 12 h; Reflux Step 3: 3-Methyl-lH-pyrazolo[3,4b]pyridine. A solution of l-(2-chloropyridin-3-yl)ethanone (22 g, 0.1415 mol) and hydrazine hydrate 98percent (113 g, 2.21 mol) in ethanol (300 mL) was refluxed for 12 h. About 80percent of the ethanol was distilled off under reduced pressure using a rotary evaporator. The residue was allowed to come to room temperature. The precipitated solid was filtered and washed with water. The product was dried at 90 0C to constant weight (16 g, 85percent) mp 152-154 0C. 1H NMR (CDCl3) 8.62 (dd, J = 4.5 and 1.4 Hz, 1 H), 8.08 (dd, J = 8.0 and 1.4 Hz, 1 H), 7.15 (dd J = 8.0 and 4.5 Hz, 1 H), 2.64 (s, 3 H). MS (FAB) m/z: 133 (M+ +1).
72% With hydrazine hydrate In butan-1-olReflux Step 3[00177] To a solution of l-(2-Chloropyridin-3-yl)ethanone (III) (0.311 g, 2 mmol) in n-butanol (10 mL) was added hydrazine hydrate (1.45 mL, 30 mmol). The reaction was refluxed overnight. The solution was cooled and the solvent was evaporated under vacuum. The residue was dissolved in DCM and washed successively by water and brine. The organic layers were dried over MgS04, filtered and concentrated under reduced pressure to give 3-methyl-lH-pyrazolo[3,4-.pound.]pyridine (IV) as a white solid (192 mg, 1.44 mmol, 72percent yield). 1H NMR (CDC13) δ ppm 2.64 (s, 3 H), 7.14 (dd, J=8.01, 4.62 Hz, 1 H), 8.14 (dd, J=7.54, 1.88 HZ, 1 H), 8.59 (dd, J=4.52, 1.32 HZ, 1 H), 11.68 (brs, 1H).
72% With hydrazine hydrate In butan-1-olReflux To a solution of 1-(2-Chloropyridin-3-yl)ethanone (XIII) (0.311 g, 2 mmol) in n-butanol (10 mL) was added hydrazine hydrate (1.45 mL, 30 mmol). The reaction was refluxed overnight. The solution was cooled and the solvent was evaporated under vacuum. The residue was dissolved in DCM and washed successively by water and brine. The organic layers were dried over MgSO4, filtered and concentrated under reduced pressure to give 3-methyl-1H-pyrazolo[3,4-b]pyridine (XIV) as a white solid (192 mg, 1.44 mmol, 72percent yield). 1H NMR (CDCl3) δ ppm 2.64 (s, 3H), 7.14 (dd, J=8.01 Hz, J=4.62 Hz, 1H), 8.14 (dd, J=7.54 Hz, J=1.88 Hz, 1H), 8.59 (dd, J=4.52 Hz, J=1.32 Hz, 1H), 11.68 (brs, 1H)
72% With hydrazine hydrate In butan-1-olReflux Step 3
To a solution of 1-(2-chloropyridin-3-yl)ethanone (XI) (0.311 g, 2 mmol) in n-butanol (10 mL) was added hydrazine hydrate (1.45 mL, 30 mmol).
The reaction was refluxed overnight.
The solution was cooled and the solvent was evaporated under vacuum.
The residue was dissolved in DCM and washed successively by water and brine.
The organic layers were dried over MgSO4, filtered and concentrated under reduced pressure to give 3-methyl-1H-pyrazolo[3,4-b]pyridine (XII) as a white solid (192 mg, 1.44 mmol, 72percent yield).
1H NMR (CDCl3) δ ppm 2.64 (s, 3H), 7.14 (dd, J=8.01 Hz, J=4.62 Hz, 1H), 8.14 (dd, J=7.54 Hz, J=1.88 Hz, 1H), 8.59 (dd, J=4.52 Hz, J=1.32 Hz, 1H), 11.68 (brs, 1H).
72% With hydrazine hydrate In butan-1-olReflux To a solution of 1-(2-chloropyridin-3-yl)ethanone (XI) (0.31 1 g, 2 mmol) in n-butanol (10 mL) was added hydrazine hydrate (1.45 mL, 30 mmol). The reaction was refluxed overnight. The solution was cooled and the solvent was evaporated under vacuum. The residue was dissolved in DCM and washed successively by water and brine. The organic layers were dried over MgSO4, filtered and concentrated under reduced pressure to give 3-methyl-1H-pyrazolo [3,4-b]pyridine (XII) as a white solid (192 mg, 1.44 mmol, 72percent yield). 1H NMR (CDCl3) δ ppm 2.64 (s, 3 H), 7.14 (dd, J=8.01Hz, J=4.62Hz, 1H), 8.14 (dd, J=7.54Hz, J=1.88Hz, 1H), 8.59 (dd, J=4.52Hz, J=1.32Hz, 1H), 1 1.68 (brs, 1H).

Reference: [1] European Journal of Medicinal Chemistry, 2012, vol. 57, p. 311 - 322
[2] Patent: US2006/47126, 2006, A1, . Location in patent: Page/Page column 30
[3] Patent: WO2011/5759, 2011, A2, . Location in patent: Page/Page column 77-78
[4] Canadian Journal of Chemistry, 1988, vol. 66, # 3, p. 420-428
[5] Patent: WO2011/84486, 2011, A1, . Location in patent: Page/Page column 106; 111
[6] Patent: US2013/296302, 2013, A1, . Location in patent: Paragraph 0495
[7] Patent: US2016/68550, 2016, A1, . Location in patent: Paragraph 1057
[8] Patent: WO2016/40193, 2016, A1, . Location in patent: Paragraph 0704
[9] Patent: WO2005/9958, 2005, A1, . Location in patent: Page 180
[10] Patent: WO2011/79804, 2011, A1, . Location in patent: Page/Page column 24
[11] Patent: US2012/245178, 2012, A1, . Location in patent: Page/Page column 13
[12] Journal of Medicinal Chemistry, 2014, vol. 57, # 18, p. 7577 - 7589
  • 21
  • [ 55676-21-6 ]
  • [ 116855-03-9 ]
Reference: [1] Canadian Journal of Chemistry, 1988, vol. 66, # 3, p. 420-428
  • 22
  • [ 55676-21-6 ]
  • [ 116855-08-4 ]
Reference: [1] Canadian Journal of Chemistry, 1988, vol. 66, # 3, p. 420-428
[2] Patent: WO2011/5759, 2011, A2,
[3] Patent: WO2011/84486, 2011, A1,
[4] Patent: US2013/296302, 2013, A1,
[5] Patent: US2016/68550, 2016, A1,
[6] Patent: WO2016/40193, 2016, A1,
  • 23
  • [ 55676-21-6 ]
  • [ 916325-85-4 ]
Reference: [1] Patent: WO2011/84486, 2011, A1,
[2] Patent: US2013/296302, 2013, A1,
[3] Patent: US2013/296302, 2013, A1,
[4] Patent: US2016/68550, 2016, A1,
[5] Patent: WO2016/40193, 2016, A1,
  • 24
  • [ 55676-21-6 ]
  • [ 916325-83-2 ]
Reference: [1] Patent: WO2011/5759, 2011, A2,
[2] Patent: WO2011/84486, 2011, A1,
[3] Patent: US2013/296302, 2013, A1,
[4] Patent: US2016/68550, 2016, A1,
[5] Patent: WO2016/40193, 2016, A1,
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