* 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 hydroxylamine hydrochloride; sodium carbonate In dichloromethane; water at 20℃; for 1 h;
92.9 g (0.876 mol) of Na2CO3 and 300 mL of purified water were added to a 1L three-necked flask, and Na2CO3 was completely dissolved by mechanical stirring. 46.83 g (0.674 mol) of hydroxylamine hydrochloride was added, and 220 mL was added dropwise with stirring at room temperature.100g (0.587mol) benzyl chloroformate solution in dichloromethane, about 4h drop;After stirring at room temperature for 1 h, 300 mL of purified water was added and the layers were separated. The aqueous layer was extracted with dichloromethane (150 mL×3); the dichloromethane phases were combined, washed with 300 mL of saturated saline, and dried over 20.0 g of anhydrous sodium sulfate; The filtrate was distilled under reduced pressure at 45°C to remove the solvent to obtain crude compound I.The crude product was dissolved in 100 mL of dichloromethane to completely dissolve the solution. After cooling and cooling in an ice-water bath, 300 mL of petroleum ether was added dropwise. The solution was crystallized at 0° C. for 1 h and suction-filtered with pre-chilled (200 mL, petroleum ether: dichloromethane=3: 1, the volume ratio) was washed with a mixed solvent and dried under reduced pressure at 35° C. for 5 h to obtain 63.0 g of a white powdery solid with an overall yield of 64percent.
Reference：
[1] Organic and Biomolecular Chemistry, 2009, vol. 7, # 21, p. 4531 - 4538
[2] Journal of Organic Chemistry, 2009, vol. 74, # 22, p. 8690 - 8694
[3] Journal of the American Chemical Society, 2010, vol. 132, # 37, p. 12862 - 12864
[4] Synthetic Communications, 2010, vol. 40, # 5, p. 642 - 646
[5] Helvetica Chimica Acta, 1991, vol. 74, # 8, p. 1653 - 1670
[6] Patent: CN107936040, 2018, A, . Location in patent: Paragraph 0036-0040; 0050-0051
[7] Organic Letters, 2017, vol. 19, # 24, p. 6574 - 6577
[8] Journal of the American Chemical Society, 1914, vol. 36, p. 2222
[9] Journal of the Chemical Society, 1960, p. 229 - 238
[10] Journal of the Chemical Society [Section] C: Organic, 1966, p. 354 - 358
[11] Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry (1972-1999), 1979, p. 2138 - 2143
[12] Organic and Biomolecular Chemistry, 2004, vol. 2, # 5, p. 695 - 700
[13] Organic and Biomolecular Chemistry, 2016, vol. 14, # 23, p. 5224 - 5228
[14] Organic Letters, 2016, vol. 18, # 21, p. 5560 - 5563
[15] Journal of Organic Chemistry, 2017, vol. 82, # 15, p. 8251 - 8257
[16] Organic and Biomolecular Chemistry, 2018, vol. 16, # 14, p. 2421 - 2426
[17] Journal of Organic Chemistry, 2018, vol. 83, # 15, p. 8233 - 8240
2
[ 501-53-1 ]
[ 3426-71-9 ]
[ 4950-01-0 ]
Yield
Reaction Conditions
Operation in experiment
70%
With hydroxylamine hydrochloride; sodium hydrogencarbonate In dichloromethane; water at 0 - 4℃; for 2 h;
Method B. Hydroxylamine hydrochloride (8.31 g, 120 mmol) is dissolved in water (200 mL) followed by the introduction of sodium bicarbonate (17.7 g, 211 mmol). Then CH2CI2 (200 mL) is added to the solution and resulting the mixture is cooled in an ice bath to 0-4 °C. Benzyl chloroformate (16.7 mL, 117 mmol) is added with vigorous stirring while maintaining the temperature below 4 °C. After addition is complete the reaction mixture is left to stir for 2 h. The biphasic reaction mixture is transferred into a separating funnel and CH2CI2 is added until the organic phase clarified. The aqueous phase is extracted with CH2CI2 (3x100 ml_) and then washed with brine, dried over MgS04 and concentrated to give a colourless solid. Flash column chromatography (silica gel, CH2CI2 then ethyl acetate/petroleum spirits 3:7 then 1:0) affords 13.7 g (70percent) of 51 as a colourless solid along with 4.60 g (13percent) of 52 as a colourless oil. Spectroscopic data are identical to those reported above.
D-methyl 2-N-benzyloxycarbonyl-aminoxy-3-phenyl propanoate[ No CAS ]
Yield
Reaction Conditions
Operation in experiment
Stage #1: Benzyl N-hydroxycarbamate; (S)-2-bromo-3-phenylpropionic acid With sodium hydride In N,N-dimethyl-formamide at 0 - 5℃;
Stage #2: methanol With thionyl chloride at 20℃; Further stages. Title compound not separated from byproducts.;
With 1,1,1,3',3',3'-hexafluoro-propanol; triethylamine In dichloromethane at 20℃; for 10.7167h; Electrochemical reaction; Inert atmosphere;
80%
With 2-ethyl-4,5-dihydrooxazole; oxygen; copper dichloride In acetonitrile at 20℃; for 144h; Air atmosphere; chemoselective reaction;
73%
With bis-[(trifluoroacetoxy)iodo]benzene In dichloromethane at 20℃; for 1h; Inert atmosphere;
General procedure for the oxidative cycloaddition reaction of hydroxamic acids with dienes andcharacterization of 1,2-oxazine 3
General procedure: To a suspension of hydroxamic acid (1a: 54.9 mg, 1b: 66.9 mg, 1c: 53.3 mg; 0.40 mmol) and diene (2a: 76.2 μL, 2b: 79.2 μL,2c: 165.1 mg; 0.80 mmol, 2d: 226 μL, 2e: 241 μL; 2.0 mmol) in DCM (4.5 mL) was added BTI (189 or 258 mg, 0.44 or0.60 mmol) or DIB (142 or 193 mg, 0.44 or 0.60 mmol) at room temperature. After being stirred at ambient temperature for1 h, the reaction mixture was quenched with sat. NaHCO3 and sat. Na2S2O3, and then extracted with DCM. The organic layerwas dried over MgSO4 and concentrated in vacuo to dryness. The residue was purified by preparative thin layerchromatography (PTLC, hexane/EtOAc 3:1 or 1:1) to give 3aa, 3ab, 3ad, 3ae, 3ba, 3bd and 3be, by column chromatographyon alumina (hexane/EtOAc 30:1-5:1) to give 3ac, 3bc and 3cc, or by column chromatography on silica gel (hexane/EtOAc30:1-5:1) to give 3ca, 3cd and 3ce.
55%
With tert.-butylhydroperoxide; tetra-(n-butyl)ammonium iodide In dichloromethane at 20℃; for 18h; Inert atmosphere; Green chemistry;
42%
With dihydrogen peroxide In acetone at 20℃; for 16h;
With tert.-butylhydroperoxide; rac-cyclohexan-1,2-bis(-N=C-C6H3-5-NO2-2-O-)Ru(PPh3)2 In hexane; dichloromethane-d2
5-hydroxy-5-methyl-3-pentyl-isoxazolidine-2-carboxylic acid benzyl ester[ No CAS ]
C17H25NO4[ No CAS ]
Yield
Reaction Conditions
Operation in experiment
Stage #1: Non-3-en-2-on With 2C13H17NO4*C20H27N3O In toluene at 20℃; for 0.166667h;
Stage #2: Benzyl N-hydroxycarbamate In toluene at 20℃; for 72h; optical yield given as %ee; enantioselective reaction;
With tris(acetonitrile)(η5-pentamethylcyclopentadienyl)rhodium(III) hexafluoroantimonate; silver carbonate In tetrahydrofuran at 100℃; for 10h; Sealed tube;
benzyl 3,6-diphenyl-3,6-dihydro-2H-1,2-oxazine-2-carboxylate[ No CAS ]
Yield
Reaction Conditions
Operation in experiment
54%
With 2,6-dimethylpyridine; tris(bipyridine)ruthenium(II) dichloride hexahydrate; In 1,2-dichloro-ethane; at 23℃; for 24h;Irradiation;
General procedure: To a stirred solution of N-substituted hydroxylamine 4 and 1,3-diene 5 in 1,2-dichloroethane (DCE)was added Ru(bpy)3Cl2*6H2O (0.01 equiv) and 2,6-lutidine (2 equiv). The reaction was suspended between two 26W white lightbulbs which were turned on for the duration of the reaction, and left to stir open to the atmosphere until reaction completion, as determined by TLC analysis of the reaction mixture. During the reaction, the flask was vigorously cooled using compressed air to ensure the reaction temperature remained at rt (approx. 23C). After completion, the solution was filtered through a plug of basic alumina and the solvent was removed in vacuo. The crude residue was purified by flash column chromatography to afford the desired 1,2-oxazine 6.
With [2,2]bipyridinyl; manganese(IV) oxide; copper(II) bis(trifluoromethanesulfonate) In 1,2-dichloro-ethane at 20℃; for 7h; Sealed tube; Inert atmosphere; regioselective reaction;
79%
With 9-(2-mesityl)-10-methylacridinium perchlorate In 1,2-dichloro-ethane at 20℃; for 58h; Schlenk technique; Irradiation;
benzyl (perfluoropyridin-4-yl)oxycarbamate[ No CAS ]
Yield
Reaction Conditions
Operation in experiment
69%
With potassium carbonate In dichloromethane at 20℃; for 4h;
69%
Stage #1: Benzyl N-hydroxycarbamate With potassium carbonate In dichloromethane at 20℃;
Stage #2: Pentafluoropyridine In dichloromethane at 20℃;
5 Example 5
The 6.0 mmol raw material hydroxylamine 2 (the structural formula is as follows),6.0mmol potassium carbonate dissolved in 15mL dichloromethane,Stir the reaction at room temperature for 12h, then add 5.0mmol pentafluoropyridine,Stir the reaction at room temperature for 6-8 hours, and then click the plate. After confirming that the reaction is complete, the reaction solution is vacuum spin-dried.Then the reaction solution was extracted 3 times with ethyl acetate and saturated sodium chloride solution,And use ethyl acetate and petroleum ether with a volume ratio of 5-8% for elution,1.09 g of white solid was obtained, with a yield of 69%.
Stage #1: Benzyl N-hydroxycarbamate With potassium carbonate In ethanol at 20℃;
Stage #2: 2,3,4,5,6-pentachloropyridine In ethanol at 20℃;
2 Example 2
Dissolve 6.0mmol of raw material hydroxylamine 2 (the structural formula is as follows) and 6.0mmol of potassium carbonate in 15mL of ethanol, stir and react at room temperature for 12h,Then add 5.0mmol of pentachloropyridine, stir and react for 6-8h at room temperature,Click the plate again, and after confirming that the reaction is complete, the reaction solution is vacuum spin-dried.Then the reaction solution was extracted with ethyl acetate and saturated sodium chloride solution for 2 to 3 times,And use ethyl acetate and petroleum ether with a volume ratio of 4 to 7% for elution,0.97 g of a white solid was obtained with a yield of 51%.
24%
With potassium carbonate In dichloromethane at 20℃; for 4h;
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