* 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.
With tetrachloromethane; sodium t-butanolate In N,N-dimethyl-formamide at 20℃; for 3 h;
Benzoxazole (1 mmol, 119.1 mg),Carbon tetrachloride (1.1 mmol, 169.2 mg) was placed in a 10 mL round bottom flask.Added 5 mL of N,N-dimethylformamide and sodium tert-butoxide (4.0 mmol, 384.4 mg).Stir at room temperature for 3 hours,TLC monitored the endpoint of the reaction.The mixture was poured into water and extracted with dichloromethane. The organic phase was collected and dried. The dichloromethane was removed by rotary evaporation to give the crude product.The crude product was subjected to silica gel column chromatography with petroleum ether and ethyl acetate as eluent (volume ratio = 30:1).2-Chlorobenzoxazole (light yellow oily liquid, 136.7 mg, yield 89percent) was obtained.
Reference：
[1] Patent: CN107501023, 2017, A, . Location in patent: Paragraph 0065; 0066
[2] Journal of Organometallic Chemistry, 1999, vol. 588, # 2, p. 155 - 159
[3] Synthesis (Germany), 2013, vol. 45, # 7, p. 936 - 942
Reference：
[1] Yakugaku Zasshi, 1953, vol. 73, p. 1316[2] Chem.Abstr., 1955, p. 299
5
[ 273-53-0 ]
[ 17200-30-5 ]
[ 70886-33-8 ]
Reference：
[1] Yakugaku Zasshi, 1953, vol. 73, p. 1316[2] Chem.Abstr., 1955, p. 299
6
[ 273-53-0 ]
[ 2382-96-9 ]
Yield
Reaction Conditions
Operation in experiment
92.6%
With 1.3-propanedithiol; potassium hydroxide In dimethyl sulfoxide at 130℃; for 12 h; Inert atmosphere; Sealed tube
Benzoxazole 119.12 mg (1.0 mmol) and 1,3-propanedithiol 325 μL (3.0 mmol), potassium hydroxide 280.55 mg (5.0 mmol), 3 mL DMSO, placed in a reaction tube equipped with a magnetic stir bar The mixture was sealed with argon, heated and stirred, and reacted in an oil bath at 130 ° C for 12 hours. After the reaction is completed, the reaction solution is transferred to a separating funnel with water washing, an appropriate amount of dilute sulfuric acid is added, the pH of the aqueous phase is adjusted to 1-3, and the organic phase is extracted with ethyl acetate, and the upper organic phase is transferred with anhydrous magnesium sulfate. dry.The mixture was decanted under reduced pressure and subjected to column chromatography to give a brown solid product (140 mg).The yield was 92.6percent.
Reference：
[1] Patent: CN108530374, 2018, A, . Location in patent: Paragraph 0022; 0023
[2] Organic and Biomolecular Chemistry, 2017, vol. 15, # 39, p. 8276 - 8279
7
[ 273-53-0 ]
[ 591-50-4 ]
[ 2688-84-8 ]
Reference：
[1] European Journal of Organic Chemistry, 2012, # 35, p. 6856 - 6860
8
[ 273-53-0 ]
[ 124-38-9 ]
[ 74-88-4 ]
[ 27383-86-4 ]
Yield
Reaction Conditions
Operation in experiment
90%
Stage #1: With 3-benzyl-1-(1-((2,6-diisopropylphenyl)imino)ethyl)-1H-imidazol-3-ium chloride; potassium <i>tert</i>-butylate In N,N-dimethyl-formamide at 80℃; for 18 h; Inert atmosphere Stage #2: at 65℃; for 1 h; Inert atmosphere
In the reaction flask, Under argon, a catalyst (9.9 mg, 0.025 mmol, 5 molpercent), Potassium tert-butoxide (0.0672 g, 0.6 mmol), DMF (3.0 mL) Benzoxazole (50.7 μl, 0.5 mmol), carbon dioxide gas, The reaction was stirred at 80 ° C for 18 hours under normal pressure. Cooled to 65 ° C, Methyl iodide (93 μl, 1.5 mmol) was added and the reaction was stirred at 65 ° C for 1 hour. The reaction was quenched with deionized water and the reaction product was extracted with ethyl acetate. The yield was 95percent by gas chromatography, The column chromatography was carried out in a volume ratio of ethyl acetate / petroleum ether 1:10 mixed solvent as developing solvent) in a yield of 90percent.
Reference：
[1] Green Chemistry, 2018, vol. 20, # 5, p. 989 - 996
[2] Organic Letters, 2010, vol. 12, # 15, p. 3567 - 3569
[3] Journal of the American Chemical Society, 2010, vol. 132, # 26, p. 8858 - 8859
[4] Patent: CN106565623, 2017, A, . Location in patent: Paragraph 0021
[5] Angewandte Chemie - International Edition, 2010, vol. 49, # 46, p. 8670 - 8673
9
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[ 27383-86-4 ]
Reference：
[1] Organic Letters, 2012, vol. 14, # 15, p. 3986 - 3989
[2] Patent: US2013/85276, 2013, A1,
[3] Green Chemistry, 2016, vol. 18, # 13, p. 3804 - 3807
With acetylhydroxamic acid; sulfuric acid In acetonitrile at 80℃; for 0.133333 h; Microwave irradiation
General procedure: 2-Hydroxy acetophenone 4a (1.0 g, 7.4 mmol), acetohydroxamic acid (0.83 g, 11.0 mmol), acetonitrile (3 ml), and conc. H2SO4 (0.2 ml) were taken into a 10 ml pressure tube and subjected to microwave heating (CEM discover, 360 W, 80 °C, 25 psi) for 8 min. Next, the reaction mixture was diluted with ethyl acetate (3 ml) and to this; saturated sodium bicarbonate solution (5 ml) was added drop-wise. The mixture was extracted with ethyl acetate (2 .x. 10 ml) and the combined organic layer was washed with saturated NaCl solution, dried over anhy. Na2SO4, and concentrated under reduced pressure. Purification of the mixture by normal column chromatography (silica gel 60-120 mesh, ethyl acetate/hexane: 1:9) gave benzoxazole 5a (0.67 g, 70percent) in the form of a yellow oil and 2-hydroxy acetophenone oxime 6a (68 mg, 6percent, mp 104-107 °C) in the form of a white powder.
In the reaction flask, Under argon, a catalyst (9.9 mg, 0.025 mmol, 5 molpercent), Potassium tert-butoxide (0.0672 g, 0.6 mmol), DMF (3.0 mL) Benzoxazole (50.7 mul, 0.5 mmol), carbon dioxide gas, The reaction was stirred at 80 ° C for 18 hours under normal pressure. Cooled to 65 ° C, Methyl iodide (93 mul, 1.5 mmol) was added and the reaction was stirred at 65 ° C for 1 hour. The reaction was quenched with deionized water and the reaction product was extracted with ethyl acetate. The yield was 95percent by gas chromatography, The column chromatography was carried out in a volume ratio of ethyl acetate / petroleum ether 1:10 mixed solvent as developing solvent) in a yield of 90percent.
With hydridotetakis(triphenylphosphine)rhodium(I); Dimethyldisulphide; 1,2-bis-(diphenylphosphino)ethane; In tetrahydrofuran; at 90℃;Inert atmosphere;
General procedure: In a two-necked flask equipped with a reflux condenser were placed RhH(PPh3)4 (4 mol%, 11.5 mg), 1,2-bis(diphenylphosphino)ethane (8 mol%, 8.0 mg), dimethyl disulfide (12 mol%, 2.7 mL), 1,3-benzothiazole 5 (1.25 mmol, 137 mL), and (alpha-methylthio)isobutyrophenone 10 (0.25 mmol, 48.6 mg) in THF (0.25 mL) under an argon atmosphere, and the solution was heated at 90C for 3 h. The solvent was removed under reduced pressure, and the residue was purified by flash column chromatography on silica gel giving 11 (19.6 mg, 43%) and isobutyrophenone 8 (14.7 mg, 40%) with the recovery of 5 (141.1 mg, 83%) and 10 (23.7 mg, 49%).
With potassium dichromate; dichloro(2,2'-bipyridine)palladium(II); copper(l) cyanide; potassium carbonate; In chlorobenzene; at 150℃; for 24h;Sealed tube; Molecular sieve;
General procedure: Under air, a reaction tube was charged with benzoxazole (0.2 mmol), dimethylsulfamoyl chloride (0.3 mmol), BipyPdCl2 (10 mol %), CuCN (20 mol %), K2CO3 (0.4 mmol), K2Cr2O7 (0.2 mmol) and dry PhCl (2 mL). The mixture was stirred at 150 o C for 24 h. After the completion of the reaction, monitored by TLC, the solvent was evaporated under reduced pressure and the residue was purified by flash column chromatography on silica gel to give the product.
With potassium dichromate; dichloro(2,2'-bipyridine)palladium(II); copper(l) cyanide; potassium carbonate; In chlorobenzene; at 150℃; for 24h;Sealed tube; Molecular sieve;
General procedure: Under air, a reaction tube was charged with benzoxazole (0.2 mmol), dimethylsulfamoyl chloride (0.3 mmol), BipyPdCl2 (10 mol %), CuCN (20 mol %), K2CO3 (0.4 mmol), K2Cr2O7 (0.2 mmol) and dry PhCl (2 mL). The mixture was stirred at 150 o C for 24 h. After the completion of the reaction, monitored by TLC, the solvent was evaporated under reduced pressure and the residue was purified by flash column chromatography on silica gel to give the product.
General procedure: An amine (1 mmol, 2 equiv) was added to a solution of Nchlorosuccinimide(149 mg, 1.1 mmol, 2.2 equiv) in CH2Cl2(5 mL) at r.t. in the dark. After 3 h, Ir(dtbpy)(ppy)2PF6 (4 mg,5 mumol, 0.01 equiv), Ph3N (245 mg, 1 mmol, 2 equiv), andbenzoxazole (60 mg, 0.5 mmol, 1 equiv) were added. Thereaction rube was sealed and placed at a distance of 5 cm from 3 W blue LED and stirred for 60 h. After the reactionwas complete, the solvent was evaporated under vacuo. Thecrude mixture was purified by flash column chromatographyeluting with a mixture of PE-EtOAc. 2-(4-Morpholinyl)benzoxazole (3a)Known compound; yellow solid; mp 85-87 C. 1H NMR(400 MHz, CDCl3): delta = 7.37 (d, J = 7.6 Hz, 1 H), 7.27 (d,J = 6.4 Hz, 1 H), 7.18 (t, J = 7.6 Hz, 1 H), 7.04 (t, J = 7.6 Hz,1 H), 3.82 (t, J = 4.4 Hz, 4 H), 3.69 (t, J = 5.2 Hz, 4 H). 13CNMR (100 MHz, CDCl3): delta = 162.0, 148.7, 142.8, 124.0,120.9, 116.4, 108.8, 66.1, 45.7.
With iron(III) oxide; copper(l) iodide; 1,10-Phenanthroline; di-tert-butyl peroxide; lithium tert-butoxide; In toluene; at 110℃; for 12h;Schlenk technique; Sealed tube; Green chemistry;
General procedure: CuI (0.1 mmol), Fe2O3(0.1 mmol), 1,10-phenanthroline(0.1mmol) ,LiOBu-t(1.0 mmol), t-BuOOBu-t(1.0 mmol), benzooxazole(0.5 mmol) and phenylboronic acid(1.0 mmol)were weighed into an oven-dried Schlenk tube which was sealed with a plug. Then toluene(3.0 mL) was added.The reaction mixture was stirred at 110 oC for 12 h. The resulting mixture was then cooled to room temperatureand diluted with ethyl acetate. The organic layer was collected, washed with water and brine, and dried overNa2SO4. After removal of the solvent in vacuo, the residue was purified by silica gel chromatography to give thedesired 2-phenylbenzo[d]oxazole.
(2-(benzo[d]oxazol-2-yl)-3-methylphenyl)(4-fluorophenyl)-methanone[ No CAS ]
Yield
Reaction Conditions
Operation in experiment
48%
With norborn-2-ene; trifuran-2-yl-phosphane; potassium carbonate; copper(I) bromide; palladium dichloride; In acetonitrile; at 100℃;Schlenk technique; Inert atmosphere;
In a dry 25 mL Schlenk reaction tube, 65 mg of o-methyl iodobenzene, 236 mg of <strong>[25569-77-1]4-fluorobenzoic anhydride</strong>, 71 mg of benzoxazole, 5.3 mg of palladium chloride,14 mg of tris(2-furyl)phosphine, 43 mg of copper bromide, 56 mg of norbornene, 124 mg of potassium carbonate, and 3 mL of acetonitrile.Under nitrogen atmosphere, stirring was performed at 100C for 16 hours.After the reaction was completed, the mixture was cooled to room temperature and insoluble material was removed by filtration and passed through a silica gel column (volume ratio of ethyl acetate to petroleum ether was 1:10) to obtain 159 mg of a product in a yield of 48%. The reaction process was as follows:
(R)-N-(2,3-dihydro-1H-inden-1-yl)-N-(prop-2-yn-1-yl)benzo[d]oxazol-2-amine[ No CAS ]
Yield
Reaction Conditions
Operation in experiment
59%
With tetra-(n-butyl)ammonium iodide; acetic acid; In acetonitrile; at 20℃;Electrochemical reaction; Green chemistry;
General procedure: A 30 mL screw capped vial with a septum was inserted carbon anode and aluminum cathode (CAUTION: Electrodes should not come in contact with each other). The electrodes were connected to a cell phone charger (5V) by use of alligator clips. To the reaction vial were added benzoxazole 1 (119 mg, 1 mmol), N-Boc piperazine 2a (372 mg, 2 mmol), acetic acid (300 mg, 5 mmol, 5 equiv.) and TBAI (37 mg, 10 mol%) and the mixture was dissolved in 20mL of acetonitrile and stirred gently at room temperature. Electric current was passed through the reaction vial at room temperature for 3 h. The progress of the reaction was monitored by TLC and LC-MS. After the completion of the reaction, the solvent was removed in vacuo and the crude material was re-dissolved in ethyl acetate (25 mL) and then washed with saturated aqueous sodium carbonate solution (3×10mL). The organic layer was separated, washed with water and then dried over sodium sulfate. The product was purified by column chromatography using hexane and ethyl acetate as eluent to afford 282 mg of compound 3a (93 % yield).
With copper(l) iodide; potassium phosphate tribasic heptahydrate; palladium diacetate; nixantphos; In N,N-dimethyl-formamide; at 120℃; for 24h;Inert atmosphere;
General procedure: 2 mol% Pd(OAc)2/3 mol% Nixantphos, anhydrous DMF (1.0 ml) were added to an oven-dried 10 ml reaction vial equipped with a stir bar, the mixture was stirred at 45 C under an argon atmosphere for 1h to be a dark brown solution. 1 mol% CuI/1.1 mol% Nixantphos, anhydrous DMF (1.0 ml) were added to an oven-dried 10 ml reaction vial equipped with a stir bar, the mixture was stirred at 60 C under an argon atmosphere for 2h to be a colorless transparent solution. The amount of catalyst and solvent should scaled up by the number of reactions. Benzoxazoles (0.25 mmol), aryl chlorides (0.3 mmol) and K3PO4*7H2O (42.3 mg, 0.125 mmol, 0.5 equiv) were added to an oven-dried 10 ml reaction vial equipped with a stir bar. A stock solution of Pd(OAc)2/Nixantphos and CuI/Nixantphos in 1 ml of dry DMF was taken up by syringe and added to the reaction vial. The reaction vial filled with argon was then sealed with a septum. The reaction mixture was stirred for12 h or 24 h at 120 C, quenched with two drops of H2O, diluted with 3 mL of ethyl acetate, and filtered over a pad of MgSO4 and silica. The pad was rinsed with additional ethyl acetate, and the solution was concentrated in vacuo. The crude material was loaded onto a silica gel column and purified by flash chromatography.
With copper(l) iodide; potassium phosphate tribasic heptahydrate; palladium diacetate; nixantphos; In N,N-dimethyl-formamide; at 120℃; for 12.0h;Inert atmosphere;
General procedure: 2 mol% Pd(OAc)2/3 mol% Nixantphos, anhydrous DMF (1.0 ml) were added to an oven-dried 10 ml reaction vial equipped with a stir bar, the mixture was stirred at 45 C under an argon atmosphere for 1h to be a dark brown solution. 1 mol% CuI/1.1 mol% Nixantphos, anhydrous DMF (1.0 ml) were added to an oven-dried 10 ml reaction vial equipped with a stir bar, the mixture was stirred at 60 C under an argon atmosphere for 2h to be a colorless transparent solution. The amount of catalyst and solvent should scaled up by the number of reactions. Benzoxazoles (0.25 mmol), aryl chlorides (0.3 mmol) and K3PO4*7H2O (42.3 mg, 0.125 mmol, 0.5 equiv) were added to an oven-dried 10 ml reaction vial equipped with a stir bar. A stock solution of Pd(OAc)2/Nixantphos and CuI/Nixantphos in 1 ml of dry DMF was taken up by syringe and added to the reaction vial. The reaction vial filled with argon was then sealed with a septum. The reaction mixture was stirred for12 h or 24 h at 120 C, quenched with two drops of H2O, diluted with 3 mL of ethyl acetate, and filtered over a pad of MgSO4 and silica. The pad was rinsed with additional ethyl acetate, and the solution was concentrated in vacuo. The crude material was loaded onto a silica gel column and purified by flash chromatography.
With copper(l) iodide; potassium phosphate tribasic heptahydrate; palladium diacetate; nixantphos; In N,N-dimethyl-formamide; at 120℃; for 24h;Inert atmosphere;
General procedure: 2 mol% Pd(OAc)2/3 mol% Nixantphos, anhydrous DMF (1.0 ml) were added to an oven-dried 10 ml reaction vial equipped with a stir bar, the mixture was stirred at 45 C under an argon atmosphere for 1h to be a dark brown solution. 1 mol% CuI/1.1 mol% Nixantphos, anhydrous DMF (1.0 ml) were added to an oven-dried 10 ml reaction vial equipped with a stir bar, the mixture was stirred at 60 C under an argon atmosphere for 2h to be a colorless transparent solution. The amount of catalyst and solvent should scaled up by the number of reactions. Benzoxazoles (0.25 mmol), aryl chlorides (0.3 mmol) and K3PO4*7H2O (42.3 mg, 0.125 mmol, 0.5 equiv) were added to an oven-dried 10 ml reaction vial equipped with a stir bar. A stock solution of Pd(OAc)2/Nixantphos and CuI/Nixantphos in 1 ml of dry DMF was taken up by syringe and added to the reaction vial. The reaction vial filled with argon was then sealed with a septum. The reaction mixture was stirred for12 h or 24 h at 120 C, quenched with two drops of H2O, diluted with 3 mL of ethyl acetate, and filtered over a pad of MgSO4 and silica. The pad was rinsed with additional ethyl acetate, and the solution was concentrated in vacuo. The crude material was loaded onto a silica gel column and purified by flash chromatography. 2-(4-(tert-butyl)phenyl)benzo[d]oxazole (3a): This reaction was performed following General Procedure with benzoxazole (1a, 29.8 mg, 25.3 mul, 0.25 mmol, 1.0 equiv) and <strong>[3972-56-3]1-(tert-butyl)-4-chlorobenzene</strong> (2a, 50.4 mg, 49.9 mul, 0.3 mmol, 1.2 equiv). The crude material was purified by flash chromatography on silica gel (eluted with petroleum ether: EtOAc = 15:1) to give the product (59.6 mg, 95%) as a white solid. 1H NMR (400 MHz, CDCl3) delta= 8.19 (d, J= 8.5 Hz, 2H), 7.79- 7.76 (m, 1H), 7.59-7.54 (m, 3H), 7.36- 7.33 (m, 2H), 1.38 (s, 9H) ppm; 13C{1H} NMR (100 MHz, CDCl3) delta = 163.3, 155.1, 150.7, 142.2, 127.5, 125.9, 124.9, 124.5, 124.4, 119.9, 110.5, 35.1, 31.2 ppm. The spectroscopic data match the previously reported data[1].
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