* All experimental methods are cited from the reference, please refer to the original source for details. We do not guarantee the accuracy of the content in the reference.
Stage #1: at 2 - 20℃; Stage #2: at 2 - 140℃; for 3.25 h;
To DMF (120 mL, 1.55 mol) at 2 °C, freshly distilled phosphorus oxychloride (61 mL, 0.65 mol) was slowly added. The temperature was allowed to rise gradually to room temperature. The solution was cooled again to 2 °C and a solution of imidazo[1,2-a]-pyridine 1 (10 g, 0.085 mol) in DMF (60 mL) was added dropwise. The mixture was warmed to 105 °C, whereupon the temperature rose to 140 °C. The oil bath was removed until the temperature stabilized at 120 °C. The reaction mixture was heated for 45 min at 120 °C and 2.5 h at 85 °C, then cooled and poured into 5percent HCl (600 mL) ice-cooled and brought to pH 9 using 20percent NaOH. The resulting solution was extracted with CH2Cl2 (1200 mL) overnight. Then the organic layer was separated and dried over MgSO4, the solvent removed under reduced pressure, the crude product washed with water (5 .x. 15 mL) and again dried, providing the pure product 3.49 g (31percent).
13%
Stage #1: for 1 h; Stage #2: With sodium hydroxide In water
a) Imidazo [1, 2-a] pyridine-3-carbaldehyde; Imidazo [1, 2-a] pyridine (0.500 g, 4.23 mmol) was dissolved in 1 mL of DMF and phosphorus oxychloride (0.71 g, 4.6 mmol) was added dropwise and the mixture was stirred and checked on LC-MS. After lh the mixture was poured into water and made alkaline with 1M NaOH. The mixture was extracted three times with EtOAc and the combined organic layer was washed with water, dried over Na2SO4, filtered and evaporated. The crude product was flash chromatographed on silica gel with DCM: MeOH 99: 1-96: 4. Yield: 83 mg (13percent). 'H NMR (300 MHz, CDCl3) 6 9.95 (s, 1H), 9.50 (m, 1H), 8.32 (s, 1H), 7.80 (m, 1H), 7.56 (m, 1H), 7.13 (m, 1H).
Reference：
[1] Farmaco, Edizione Scientifica, 1981, vol. 36, # 12, p. 994 - 1003
[2] Journal of Medicinal Chemistry, 2010, vol. 53, # 9, p. 3454 - 3464
[3] European Journal of Medicinal Chemistry, 2011, vol. 46, # 10, p. 4820 - 4826
[4] Journal of Medicinal Chemistry, 1996, vol. 39, # 14, p. 2856 - 2859
[5] Patent: WO2005/66132, 2005, A1, . Location in patent: Page/Page column 89-90
[6] Tetrahedron Letters, 2001, vol. 42, # 17, p. 3077 - 3080
2
[ 274-76-0 ]
[ 67-68-5 ]
[ 6188-43-8 ]
Yield
Reaction Conditions
Operation in experiment
86%
at 100℃; for 12 h;
FeCl3 (0.025 mmol, 4 mg) and AcOH (0.1 mmol, 6 mg) was mixed with DMSO (3 mL) in a glass vial or round-bottom flask equipped with a magnetic stirring bar. Then, substrate 1 (0.5 mmol) was added. The mixture was stirred under an dioxygen atmosphere (1 atm) at 100°C for 12 h. After cooling down to room temperature, 5 mL of ethyl acetate was added and removal of the DMSO with brine, the residue was purified by flash chromatography on silica gel to obtain the desired product 2 using light petroleum ether/ethyl acetate (4:1, v/v) as eluent, which furnished the 3-formylimidazo[1,2-a]pyridine.
Reference：
[1] Tetrahedron Letters, 2016, vol. 57, # 34, p. 3870 - 3872
[2] Chemical Communications, 2015, vol. 51, # 10, p. 1823 - 1825
3
[ 117459-95-7 ]
[ 6188-43-8 ]
Reference：
[1] Journal of Organic Chemistry, 2013, vol. 78, # 3, p. 1266 - 1272
[2] Chemical Communications, 2011, vol. 47, # 17, p. 5043 - 5045
[3] European Journal of Organic Chemistry, 2013, # 1, p. 35 - 39
[4] European Journal of Organic Chemistry, 2013, # 1, p. 35 - 39
[5] European Journal of Organic Chemistry, 2013, # 1, p. 35 - 39
4
[ 274-76-0 ]
[ 110-18-9 ]
[ 6188-43-8 ]
Reference：
[1] Organic and Biomolecular Chemistry, 2018, vol. 16, # 18, p. 3473 - 3478
5
[ 2717-95-5 ]
[ 6188-43-8 ]
Reference：
[1] Patent: US5760021, 1998, A,
6
[ 1284210-49-6 ]
[ 6200-59-5 ]
[ 6188-43-8 ]
Reference：
[1] Chemical Communications, 2011, vol. 47, # 17, p. 5043 - 5045
7
[ 504-29-0 ]
[ 624-67-9 ]
[ 6188-43-8 ]
Reference：
[1] Journal of Organic Chemistry, 2014, vol. 79, # 22, p. 11209 - 11214
[2] Advanced Synthesis and Catalysis, 2015, vol. 357, # 1, p. 46 - 50
8
[ 117459-95-7 ]
[ 6200-59-5 ]
[ 6188-43-8 ]
Reference：
[1] Chemical Communications, 2011, vol. 47, # 17, p. 5043 - 5045
9
[ 5866-28-4 ]
[ 6188-43-8 ]
Reference：
[1] Angewandte Chemie - International Edition, 2011, vol. 50, # 25, p. 5678 - 5681
10
[ 504-29-0 ]
[ 2065-75-0 ]
[ 6188-43-8 ]
Reference：
[1] Chinese Chemical Letters, 2015, vol. 26, # 1, p. 118 - 120
[2] Patent: WO2006/128692, 2006, A2, . Location in patent: Page/Page column 64; 65
11
[ 1284210-49-6 ]
[ 6188-43-8 ]
Reference：
[1] Chemical Communications, 2011, vol. 47, # 17, p. 5043 - 5045
[2] Chemical Communications, 2011, vol. 47, # 17, p. 5043 - 5045
[3] Chemical Communications, 2011, vol. 47, # 17, p. 5043 - 5045
[4] European Journal of Organic Chemistry, 2013, # 1, p. 35 - 39
[5] European Journal of Organic Chemistry, 2013, # 1, p. 35 - 39
[6] European Journal of Organic Chemistry, 2013, # 1, p. 35 - 39
[7] European Journal of Organic Chemistry, 2013, # 1, p. 35 - 39
12
[ 38427-94-0 ]
[ 6188-43-8 ]
Reference：
[1] Chemical Communications, 2011, vol. 47, # 17, p. 5043 - 5045
[2] Chemical Communications, 2011, vol. 47, # 17, p. 5043 - 5045
[3] Chemical Communications, 2011, vol. 47, # 17, p. 5043 - 5045
[4] European Journal of Organic Chemistry, 2013, # 1, p. 35 - 39
[5] European Journal of Organic Chemistry, 2013, # 1, p. 35 - 39
[6] European Journal of Organic Chemistry, 2013, # 1, p. 35 - 39
[7] European Journal of Organic Chemistry, 2013, # 1, p. 35 - 39
13
[ 117459-95-7 ]
[ 5857-45-4 ]
[ 30489-43-1 ]
[ 6188-43-8 ]
Reference：
[1] European Journal of Organic Chemistry, 2013, # 1, p. 35 - 39
[2] Journal of Organic Chemistry, 2013, vol. 78, # 3, p. 1266 - 1272
14
[ 504-29-0 ]
[ 6188-43-8 ]
Reference：
[1] Angewandte Chemie - International Edition, 2011, vol. 50, # 25, p. 5678 - 5681
[2] European Journal of Organic Chemistry, 2013, # 1, p. 35 - 39
[3] European Journal of Organic Chemistry, 2013, # 1, p. 35 - 39
[4] European Journal of Organic Chemistry, 2013, # 1, p. 35 - 39
[5] European Journal of Organic Chemistry, 2013, # 1, p. 35 - 39
15
[ 117459-95-7 ]
[ 5857-45-4 ]
[ 6188-43-8 ]
Reference：
[1] European Journal of Organic Chemistry, 2013, # 1, p. 35 - 39
[2] Journal of Organic Chemistry, 2013, vol. 78, # 3, p. 1266 - 1272
16
[ 117459-95-7 ]
[ 1309357-89-8 ]
[ 6188-43-8 ]
Reference：
[1] Chemical Communications, 2011, vol. 47, # 17, p. 5043 - 5045
17
[ 5857-45-4 ]
[ 6188-43-8 ]
Reference：
[1] European Journal of Organic Chemistry, 2013, # 1, p. 35 - 39
18
[ 504-29-0 ]
[ 63247-73-4 ]
[ 6188-43-8 ]
Reference：
[1] Russian Journal of Organic Chemistry, 2005, vol. 41, # 9, p. 1397 - 1398
19
[ 74944-12-0 ]
[ 6188-43-8 ]
Reference：
[1] Chemistry of Heterocyclic Compounds (New York, NY, United States), 1980, vol. 16, # 4, p. 409 - 417[2] Khimiya Geterotsiklicheskikh Soedinenii, 1980, vol. 16, # 4, p. 528 - 537
20
[ 274-76-0 ]
[ 6188-43-8 ]
Reference：
[1] Chemistry of Heterocyclic Compounds (New York, NY, United States), 1980, vol. 16, # 4, p. 409 - 417[2] Khimiya Geterotsiklicheskikh Soedinenii, 1980, vol. 16, # 4, p. 528 - 537
In a 25 mL test tube, add 0.2 mmol of the compound imidazole [1,2-a] pyridine,Copper nitrate trihydrate 0.1 mmol,Add 2 ml of N, N-dimethylformamide (DMF) as the reaction solvent,A balloon filled with oxygen,Stir at 130 C.After the TLC (thin layer chromatography) detection reaction is completed, the reaction solution is cooled to room temperature.Take off the balloon,Slowly vent unreacted oxygen.Reaction liquid filtration,The filtrate was rotary evaporated under reduced pressure to remove the solvent.Then separated and purified by column chromatography,To give the compound imidazole [1,2-a] pyridin-3-aldehyde,The yield of this step is 35%.
31%
To DMF (120 mL, 1.55 mol) at 2 C, freshly distilled phosphorus oxychloride (61 mL, 0.65 mol) was slowly added. The temperature was allowed to rise gradually to room temperature. The solution was cooled again to 2 C and a solution of imidazo[1,2-a]-pyridine 1 (10 g, 0.085 mol) in DMF (60 mL) was added dropwise. The mixture was warmed to 105 C, whereupon the temperature rose to 140 C. The oil bath was removed until the temperature stabilized at 120 C. The reaction mixture was heated for 45 min at 120 C and 2.5 h at 85 C, then cooled and poured into 5% HCl (600 mL) ice-cooled and brought to pH 9 using 20% NaOH. The resulting solution was extracted with CH2Cl2 (1200 mL) overnight. Then the organic layer was separated and dried over MgSO4, the solvent removed under reduced pressure, the crude product washed with water (5 × 15 mL) and again dried, providing the pure product 3.49 g (31%).
13%
a) Imidazo [1, 2-a] pyridine-3-carbaldehyde; Imidazo [1, 2-a] pyridine (0.500 g, 4.23 mmol) was dissolved in 1 mL of DMF and phosphorus oxychloride (0.71 g, 4.6 mmol) was added dropwise and the mixture was stirred and checked on LC-MS. After lh the mixture was poured into water and made alkaline with 1M NaOH. The mixture was extracted three times with EtOAc and the combined organic layer was washed with water, dried over Na2SO4, filtered and evaporated. The crude product was flash chromatographed on silica gel with DCM: MeOH 99: 1-96: 4. Yield: 83 mg (13%). 'H NMR (300 MHz, CDCl3) 6 9.95 (s, 1H), 9.50 (m, 1H), 8.32 (s, 1H), 7.80 (m, 1H), 7.56 (m, 1H), 7.13 (m, 1H).
Sodium borohydride (1.61 g, 2.1 eq) was added to a solution of aldehyde 3 (2.92 g, 0.02 mol) in 400 mL of MeOH. The homogenous solution was refluxed for 1 h (oil bath, 75 C). The progress of the reaction was checked either by NMR (evaporation of 1 mL of reaction mixture, dissolution in CDCl3) or by TLC (acetone, Rf(substrate) = 0.56, Rf(product) = 0.24). The reaction mixture was cooled to RT, quenched with 30 mL of 6 N HCl, evaporated to dryness and treated with 70 mL of saturated sodium carbonate solution. The resulting non-homogenous mixture was evaporated to dryness and the semi-solid residue extracted with CH2Cl2 (5 × 110 mL), and then for another 2 h with 60 mL of CH2Cl2. The combined organic extracts were dried over Na2SO4 and evaporated to dryness, giving 2.53 g of product (85.5%).
b) (1S, 35)-N-(6-Fluoro-4-methylquinolin-2-yl)-N'-(imidazo [1, 2-a] pyridin-3- ylmethyl) cyclopentane-1, 3-diamine; (15, 3S)-N-(6-Fluoro-4-methylquinolin-2-yl) cyclopentane-1, 3-diamine (76 mg, 0.29 mmol) and imidazo [1, 2-a] pyridine-3-carbaldehyde (43 mg, 0.29 mmol) were dissolved in 2 mL of DCM and allowed to react for 4h. Sodium triacetoxyborohydride (112 mg, 0.53 mmol) was added and the mixture was stirred overnight. Much of the imine was left according to LC-MS. Sodium borohydride (50 mg, 1.3 mmol) was added and stirring was continued for 30 min. The mixture was acidified with 2M HCl and after 5 min the mixture was poured into water which was made alkaline with 2M NaOH. The mixture was extracted three times with EtOAc and the combined organic layer was washed with water, dried over Na2SO4, filtered and evaporated. The crude product was chromatographed on a 2 g Isolute Si column with DCM/MeOH/TEA 100/5/1. Yield: 91 mg (77%). 1H NMR (400 MHz, CDCl3) 6 8.29 (m, 1H), 7.60 (dd, 1H), 7.56 (m, 1H), 7.46 (s, 1H), 7.31 (dd, 1H), 7.23 (m, 1H), 7.13 (m, 1H), 6.77 (m, 1H), 6.46 (s, 1H), 4.85 (bd, 1H), 4.44 (m, 1H), 4.03 (s, 2H), 3.29 (m, 1H), 2.44 (bd, 3H), 2.27 (m, 1H), 2.10-1. 95 (m, 2H), 1.77 (m, 1H), 1.55-1. 35 (m, 2H). 13C NMR (100 MHz, CDC13) 6 159.9, 157.5, 156.9, 147.0, 145.7, 145.12, 145.08, 133.1, 129.2, 129.1, 125.7, 124.9, 124.8, 124.7, 123.3, 119.3, 119.1, 118.5, 113.0, 112.8, 108.6, 108.4, 58.6, 52.3, 43.0, 41.5, 33.1, 32.7, 19.7. LC-MS [M+H] + 390.2.
ethyl 2-(N,N-dimethylamino)-3-(imidazo[1,2-a]pyridine)propenoate[ No CAS ]
Yield
Reaction Conditions
Operation in experiment
With NaH;
To a stirred, ice-cooled suspension of 3.6 g (0.15 mole) of NaH in about 100 ml of anhydrous ether is added a mixture of 12.85 g (0.088 mole) of 3-(imidazo[1,2-a]pyridine)carboxaldehyde and 23.4 g (0.178 mole) of N,N-dimethylglycine ethyl ester in 50 ml of ether. This is added over about one hour. The reaction mixture is stirred for about 18 hours, while it warms to room temperature during that time. It is then cooled in ice, and about 50 ml of saturated aqueous NH4 Cl is added. The layers are separated, and the water layer is extracted with ether. The combined organic layers are dried and distilled under high vacuum to give ethyl 2-(N,N-dimethylamino)-3-(imidazo[1,2-a]pyridine)propenoate.
With hexamethylenetetramine; In water; propionic acid;
Synthesis of 3-(Imidazo[1,2-a]pyridine)carboxaldehyde A solution of 1.75 g (0.01 mole) of 3-(N,N-dimethylaminomethyl)imidazo[1,2-a]pyridine (prepared as by Lombardino, J. Org. Chem. 30, 2403 (1965)) and 1.40 g (0.01 mole) of hexamethylenetetramine in 15 ml of 66% propanoic acid is added dropwise over 2-3 hours to a refluxing solution of 1.4 g of hexamethylenetetramine in 10 ml 66% propanoic acid. The reaction is heated at reflux a further 2 hours, and is then cooled to room temperature. Water is added, causing 3-(imidazo[1,2-a]pyridine)carboxaldehyde to precipitate.
2-[(imidazo[1,2-a]pyridin-3-ylmethyl)thio]-1H-benzimidazole[ No CAS ]
Yield
Reaction Conditions
Operation in experiment
With sodium borohydrid; In hydrogenchloride; methanol;
The resultant solid was collected by filtration, washed with water, and air dried to yield 1.8 g of 3-imidazo[1,2-a]pyridinecarboxaldehyde as the analytically pure p hydrate. [Calcd. for C8 H6 N2 O.H2 O: C, 58.53; H, 3.68; N, 17.06. Found: C, 58.77; H, 3.68; N, 17.48.]To a solution of 1.6 g (10 mmole) of 3-imidazo[1,2-a]-pyridinecarboxaldehyde in 15 ml of methanol was added 204 mg (5.4 mmole) of sodium borohydride. After one hour the mixture was acidified with concentrated hydrochloric acid and then concentrated in vacuo. Recrystallization of the residue from ethanol yielded 707 mg of 3-hydroxymethylimidazo[1,2-a]pyridine as the hydrochloride salt. A 500 mg (2.7 mmole) portion of the hydroxymethyl compound was dissolved in 3.0 ml of concentrated hydrochloric acid and heated at 80 for one hour.
1-(imidazo[1,2-a]pyridin-3-ylmethyl)-4-phenylpyrrolidin-2-one[ No CAS ]
Yield
Reaction Conditions
Operation in experiment
8%
With triethylamine; In 1,4-dioxane; ethanol; at 20℃; for 72h;
A solution of 2-aminopyridine x8 (1 g, 1 eq, 10.6 mmol) and bromomalonaldehyde x9 (1.6 g, 1 eq, 10.6 mmol) in 1.4-dioxane (20 ml) is refluxed for 3 days (lmidazo[1 ,2- a]pyridine-3-carbaldehyde x10 is formed in situ and not isolated). After cooling to room temperature, triethylamine (2.96 ml, 2 eq, 21.25 mmol), methyl 4-amino-3- phenylbutanoate hydrochloride x11 (2.44 g, 1 eq, 10.6 mmol) and ethanol (10 ml) are successively added. The mixture is then allowed to react during 3 days at room temperature. The reaction mixture is poured on ice, and organic solvents are removed EPO <DP n="66"/>under reduced pressure. The resulting aqueous layer is extracted by CH2CI2 and the cumulated organic layers are dried over MgSOphi filtered, and condensed under reduced pressure. The crude product is purified by preparative chromatography on silicagel (CH2Cl2/iPrOH: 97/3 (v/v)), then recristallized in ethyl acetate leading to 1-(imidazo[1 ,2- a]pyridin-3-ylmethyl)-4-phenylpyrrolidin-2-one 7 as a white powder.Yield: 8 %.LC-MS (MH+): 292.
In ethanol; water; at 100℃; for 0.333333h;Inert atmosphere; Microwave irradiation; Green chemistry;
General procedure: 6-bromo-2-aminopyridine (0.208 g, 1.2 mmol, 1 eq.) and 2-bromomalonaldehyde (0.272 g, 1.8 mmol, 1.5 eq.) were dissolved in the mixture of ethanol and water (v/v 1:1, total 2 ml) and placed in the pressure vial, equipped with a magnetic bar. The mixture was stirred for 1 min and purge with argon via syringe. Then microwave (MW) irradiation (with initial 150 W power) was applied. Depending on the substituents present in 2-aminopyridine 1, the following conditions were applied: a) for 2-aminopyridines substituted with halogen, or nitro or cyano groups: 10 min, 110 C; or b) for 2-aminopyridines substituted with methyl or phenyl groups: 20 min, 100 C. Afterwards, the reaction mixture was evaporated. Next the reaction mixture was neutralized with TEA, diluted with DCM (10 mL), and adsorbed on silica gel (~3 g).* The solvent was evaporated, and the residue was subjected to column chromatography using gradient DCM/acetone (100:0 => 75:25) as eluent to give product as yellow powder.
In 1,4-dioxane; for 72h;Heating / reflux;
A solution of 2-aminopyridine x8 (1 g, 1 eq, 10.6 mmol) and bromomalonaldehyde x9 (1.6 g, 1 eq, 10.6 mmol) in 1.4-dioxane (20 ml) is refluxed for 3 days (lmidazo[1 ,2- a]pyridine-3-carbaldehyde x10 is formed in situ and not isolated). After cooling to room temperature, triethylamine (2.96 ml, 2 eq, 21.25 mmol), methyl 4-amino-3- phenylbutanoate hydrochloride x11 (2.44 g, 1 eq, 10.6 mmol) and ethanol (10 ml) are successively added. The mixture is then allowed to react during 3 days at room temperature. The reaction mixture is poured on ice, and organic solvents are removed EPO <DP n="66"/>under reduced pressure. The resulting aqueous layer is extracted by CH2CI2 and the cumulated organic layers are dried over MgSOphi filtered, and condensed under reduced pressure. The crude product is purified by preparative chromatography on silicagel (CH2Cl2/iPrOH: 97/3 (v/v)), then recristallized in ethyl acetate leading to 1-(imidazo[1 ,2- a]pyridin-3-ylmethyl)-4-phenylpyrrolidin-2-one 7 as a white powder.Yield: 8 %.LC-MS (MH+): 292.
Triethylamine (0.27 ml_, 1.95 mmol) is added to a solution of ethyl 4-(aminomethyl)- heptanoate hydrochloride a52 (0.435 g, 1.95 mmol) in absolute Et^O (7 ml_). The formed precipitate is separated by filtration, and the filtrate is evaporated under reduced pressure.The residue is dissolved in dichloromethane (3.6 ml_), and imidazo[1 ,2-a]pyridine-3- carbaldehyde (0.284 g, 1.95 mmol) and Ti(O-iPr)4 (0.94 ml_, 3.14 mmol) are added to the obtained solution. The mixture is stirred at room temperature for 3 h, and the solvents are removed under reduced pressure. The residue is dissolved in absolute methanol (0.5 ml_), and NaBH4 (0.116 g, 3.06 mmol) is added under stirring. After 15 min, the reaction mixture is quenched by the addition of a 0.1 N NaOH solution (5 ml_). The mixture is stirred for 10 <n="75"/>min, diluted with dichloromethane (20 ml_), and passed through a Celite path. Celite is washed with dichloromethane, and the filtrate is evaporated. The residue (0.58 g) is subjected to rough purification by flash chromatography on silicagel (chloroform/methanol 50/1 v/v) to give a crude product. According to the ^ H NMR and LC-MS data, this product consists of the mixture of compound 21 , its non-cyclized form (corresponding aminoester), and 5-propylvalerolactame. This mixture is dissolved in toluene (3 ml.) and refluxed for 4.5 h. Toluene is removed under reduced pressure, and the residue is purified by reverse phase HPLC (C18 column; gradient acetonitrile/water/TFA from 20/80/0.1 to 85/15/0.1 v/v/v) to give 1-(imidazo[1 ,2-a]pyridin-3-ylmethyl)-5-propylpiperidin-2-one trifluoroacetate 21 (0.149 g). Yield: 20 %. LC-MS (MH+): 272.
With iodine pentoxide; 2,2,6,6-Tetramethyl-1-piperidinyloxy free radical; In water; acetonitrile; at 80℃; for 2h;
0.3mmolN-allyl-2-aminopyridine, 0.15 mmol of diiodine pentoxide, 0.6 mmol2,2,6,6-tetramethylpiperidine nitrogen oxide was added to a 15 mL thick-wall pressure-resistant reaction tube,An additional 3 mL of solvent (acetonitrile: water = 800: 1) was added. then,Magnetic stir at 80 C for 2 hours. After cooling to room temperature,Add two spoons of silica gel (100-200 mesh) to the reaction solution.The solvent was removed by distillation under reduced pressure, and the product represented by the structural formula was obtained by column chromatography (petroleum ether / ethyl acetate = 10: 1 as eluent). This material was a yellow-white solid with a yield of 47%.
E)-ethyl 3-(imidazo [ 1 ,2-a] pyridin-3-yl)acrylate(Ethoxycarbonylmethylene)triphenylphosphorane (0.72 g, 2.05 mmol) was added to a solution of imidazo[l,2-a]pyridine-3-carbaldehyde (0.25 g, 1.71 mmol) in anhydrous tetrahydrofuran (THF) (20mL) at room temperature. The reaction mixture was heated overnight at 65C. After completion of the reaction as indicated by HPLC, the reaction mixture was diluted with ethyl acetate (EtOAc) (20mL) and quenched with a saturated solution of ammonium chloride (10 mL). The organic layer was washed with water (3 x 20 mL) and brine (15 mL). It was dried over anhydrous Na2S04, filtered and evaporated to get the crude product. This crude was purified by silica gel column chromatography using 50-80% EtOAc in Hexanes to provide pure (E)-ethyl 3-(imidazo[l,2-a]pyridin-3- yl)acrylate (0.19 g) as a white solid. ES+ (M+H)+ 217.
0.19 g
In tetrahydrofuran; at 20 - 65℃;
(E)-ethyl 3-(imidazo[1,2-a]pyridin-3-yl)acrylate (Ethoxycarbonylmethylene)triphenylphosphorane (0.72 g, 2.05 mmol) was added to a solution of <strong>[6188-43-8]imidazo[1,2-a]pyridine-3-carbaldehyde</strong> (0.25 g, 1.71 mmol) in anhydrous tetrahydrofuran (THF) (20 mL) at room temperature. The reaction mixture was heated overnight at 65 C. After completion of the reaction as indicated by HPLC, the reaction mixture was diluted with ethyl acetate (EtOAc) (20 mL) and quenched with a saturated solution of ammonium chloride (10 mL). The organic layer was washed with water (3*20 mL) and brine (15 mL). It was dried over anhydrous Na2SO4, filtered and evaporated to get the crude product. This crude was purified by silica gel column chromatography using 50-80% EtOAc in Hexanes to provide pure (E)-ethyl 3-(imidazo[1,2-a]pyridin-3-yl)acrylate (0.19 g) as a white solid. ES+(M+H)+217.
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