2 Bromoethanol Synthesis Essay

3.1. Chemistry

Melting points were recorded on an X-4 microscope melting point apparatus (Beijing Tech Instrument Co., Ltd., Beijing, China) without calibration. The 1H-NMR and 13C-NMR spectra were measured by a Bruker AV-400 spectrometer (Bruker Bioscience, Billerica, MA, USA), with tetramethylsilane as an internal standard. High-resolution mass spectra (HRMS) were measured with an Agilent Accurate-Mass Q-TOF 6530 (Agilent, Santa Clara, CA, USA) in ESI mode. Reaction progress was monitored by TLC on silica gel precoated GF254 plates (Qingdao Haiyang Chemical Co. Ltd., Qingdao, Shandong, China). Preparative flash column chromatography was performed on the 200–300 mesh silica gel (Qingdao Haiyang Chemical Co. Ltd., Qingdao, Shandong, China). Unless otherwise noted, all solvents and reagents were commercially available and used without further purification.

3.1.1. General Procedure for the Synthesis of Compounds 1ad

A solution of 1,3-dihydroxybenzene (11.0 g, 100 mmol) in substituted ethyl acetoacetate (100 mmol) was added dropwise to stirring H2SO4 kept at 0 °C. After completion of the addition, the reaction mixture was kept stirring for 12 h at room temperature and then poured onto ice-water. The crude products were filtrated and recrystallized from ethanol [18].

7-Hydroxy-4-methyl-2H-chromen-2-one (1a): White solid; yield 73%. ESI-HRMS [M + H]+: (m/z) Calcd. for C10H9O3: 177.0546. Found: 177.0556.

7-Hydroxy-4-(trifluoromethyl)-2H-chromen-2-one (1b): White solid; yield 52%. ESI-HRMS [M − H]: (m/z) Calcd. for C10H6F3O3: 231.0275. Found: 231.0162.

7-Hydroxy-3,4-dimethyl-2H-chromen-2-one (1c) White solid; yield 76%. ESI-HRMS [M + H]+: (m/z) Calcd. for C11H11O3: 191.0703. Found: 191.0712.

3-Chloro-7-hydroxy-4-methyl-2H-chromen-2-one (1d): White solid; yield 74%. ESI-HRMS [M + H]+: (m/z) Calcd. for C10H8ClO3: 211.0156. Found: 211.0166.

3.1.2. The Synthesis of Compound 1e

2, 4-dihydroxybenzaldehyde (6.9 g, 0.05 mol), diethyl malonate (9.6 g, 0.06 mol) and piperidine (0.2 g, 2.5 mmol) were refluxing in 150 mL ethanol for 10 h. After cooled to room temperature, the crude products were filtrated and recrystallized from methanol [19].

Ethyl 7-hydroxy-2-oxo-2H-chromene-3-carboxylate (1e): Light yellow solid; yield 81%. ESI-HRMS [M + Na]+: (m/z) Calcd. for C12H10O5Na: 257.0420. Found: 257.0434.

3.1.3. General procedure for the synthesis of compounds 2ae, 3ae

The compounds 2ae and 3ae were synthesized according to the method from literature [26,27,28]. To a solution of compound 1ae (10.0 mmol) in acetone (30 mL), 1,2–dibromoethane or 1,3-dibromopropane (30.0 mmol) and potassium carbonate (12.3 mmol) were added. The reaction mixture was stirred at 56 °C for 10 h, then poured into water, and extracted with ethyl acetate (30 mL × 3). The organic layer was dried over anhydrous Na2SO4 and concentrated under reduced pressure.

7-(2-Bromoethoxy)-4-methyl-2H-chromen-2-one (2a): White solid; yield 62%. ESI-HRMS [M + H]+: (m/z) Calcd. for C12H12BrO3: 282.9964. Found: 282.9981.

7-(2-Bromoethoxy)-4-(trifluoromethyl)-2H-chromen-2-one (2b): White solid; yield 53%. ESI-HRMS [M + H]+: (m/z) Calcd. for C12H9BrF3O3: 336.9682. Found: 336.9712.

7-(2-Bromoethoxy)-3,4-dimethyl-2H-chromen-2-one (2c): White solid; yield 67%. ESI-HRMS [M + H]+: (m/z) Calcd. for C13H14BrO3: 297.0121. Found: 297.0129.

7-(2-Bromoethoxy)-3-chloro-4-methyl-2H-chromen-2-one (2d): White solid; yield 70%. ESI-HRMS [M + H]+: (m/z) Calcd. for C12H11BrClO3: 316.9575. Found: 316.9589.

Ethyl 7-(2-bromoethoxy)-2-oxo-2H-chromene-3-carboxylate (2e): Yellow solid; yield 65%. ESI-HRMS [M + H]+: (m/z) Calcd. for C14H14BrO5: 341.0019. Found: 341.0036.

7-(3-Bromopropoxy)-4-methyl-2H-chromen-2-one (3a): White solid; yield 62%. ESI-HRMS [M + H]+: (m/z) Calcd. for C13H14BrO3: 297.0121. Found: 297.0132.

7-(3-Bromopropoxy)-4-(trifluoromethyl)-2H-chromen-2-one (3b): White solid; yield 62%. ESI-HRMS [M + H]+: (m/z) Calcd. for C13H11BrF3O3: 350.9838. Found: 350.9851.

7-(3-Bromopropoxy)-3,4-dimethyl-2H-chromen-2-one (3c): White solid; yield 62%. ESI-HRMS [M + H]+: (m/z) Calcd. for C14H16BrO3: 311.0277. Found: 311.0284.

7-(3-Bromopropoxy)-3-chloro-4-methyl-2H-chromen-2-one (3d): White solid; yield 62%. ESI-HRMS [M + H]+: (m/z) Calcd. for C13H13BrClO3: 330.9731. Found: 330.9748.

Ethyl 7-(3-bromopropoxy)-2-oxo-2H-chromene-3-carboxylate (3e): Yellow solid; yield 62%. ESI-HRMS [M + H]+: (m/z) Calcd. for C15H16BrO5: 355.0176. Found: 355.0183.

3.1.4. General Procedure for the Synthesis of Compounds 4ae

To a solution of compound 1a (10.0 mmol) in DMF (20 mL), propargyl bromide (1.30 g, 10.9 mmol) and potassium carbonate (1.70 g, 12.3 mmol) were added. The reaction mixture was stirred at 60 °C for 5 h, then was diluted with ethyl acetate (80 mL) and washed with water (100 mL × 2). The organic layer was dried over anhydrous Na2SO4 and concentrated under reduced pressure. The crude products 4a were used without purification.

The compounds 4be were synthesized by the same operation procedure of compound 4a.

4-Methyl-7-(prop-2-yn-1-yloxy)-2H-chromen-2-one (4a): White solid; yield 91%; m.p. 129–132 °C. ESI-HRMS [M + H]+: (m/z) Calcd. for C13H10O3: 215.0703. Found: 215.0715.

7-(Prop-2-yn-1-yloxy)-4-(trifluoromethyl)-2H-chromen-2-one (4b): White solid; yield 78%; m.p. 82–84 °C. ESI-HRMS [M + H]+: (m/z) Calcd. for C13H8F3O3: 269.0420. Found: 269.0437.

3,4-Dimethyl-7-(prop-2-yn-1-yloxy)-2H-chromen-2-one (4c): White solid; yield 85%; m.p. 118–122 °C. ESI-HRMS [M + H]+: (m/z) Calcd. for C14H13O3: 229.0859. Found: 229.0875.

3-Chloro-4-methyl-7-(prop-2-yn-1-yloxy)-2H-chromen-2-one (4d):White solid; yield 82%; m.p. 131–134 °C. ESI-HRMS [M + H]+: (m/z) Calcd. for C13H10ClO3: 249.0313. Found: 249.0323.

Ethyl 2-oxo-7-(prop-2-yn-1-yloxy)-2H-chromene-3-carboxylate (4e): White solid; yield 79%; m.p. 122–124 °C. ESI-HRMS [M + H]+: (m/z) Calcd. for C15H13O5: 273.0757. Found: 273.0764.

3.1.5. General Procedure for the Synthesis of Compounds 7a, 7b, 9a

To a solution of DHA (10.0 mmol) and 2-bromoethanol (10.0 mmol) in CH2Cl2 (30 mL), boron fluoride ethyl ether (0.5 mL) was added dropwise at 0 °C. The reaction mixture was stirred at 0 °C for 8 h, then washed with saturated NaHCO3 solution (20 mL × 3). The organic layer was dried over anhydrous Na2SO4 and concentrated under reduced pressure. The crude products were purified by silica gel column chromatography (PET/EtOAc = 10:1, v/v) to get the target compound 7a.

The compounds 7b and 9a were synthesized by the same operation procedure of compound 7a.

1-Bromo-2-(10β-dihydroartemisinoxy)ethane (7a): White solid; yield 87%; m.p. 72–74 °C. 1H-NMR (400 MHz, CDCl3) δ (ppm): 0.94 (d, J = 7.2 Hz, 3H), 0.96 (d, J

IUPAC Name

2-bromoethanol

InChI

InChI=1S/C2H5BrO/c3-1-2-4/h4H,1-2H2

InChI Key

LDLCZOVUSADOIV-UHFFFAOYSA-N

Canonical SMILES

C(CBr)O

MeSH Synonyms

2-bromoethanol, ethylene bromohydrin, ethylene bromohydrin, 1-(13)C-labeled cpd, ethylene bromohydrin, 14C-labeled cpd, ethylene bromohydrin, 2-(14)C-labeled cpd

Depositor-Supplied Synonyms

2-BROMOETHANOL, Ethylene bromohydrin, Ethanol, 2-bromo-, 540-51-2, 2-bromoethan-1-ol, 2-Bromo-1-ethanol, Bromoethanol, 2-Hydroxyethyl bromide, Glycol bromohydrin, 1-Bromo-2-ethanol, Ethylenebromohydrin, 2-Bromoethyl alcohol, 2-bromo-ethanol, CCRIS 3862, LDLCZOVUSADOIV-UHFFFAOYSA-N, NSC 2869, EINECS 208-748-1, BRN 0878140, AI3-15350, BRJ, 2bromoethanol, 2-bromo ethanol, 2-bromanylethanol, 2- bromo ethanol, 1-bromoethan-2-ol, beta-bromoethyl alcohol, CH2BrCH2OH(trans), ACMC-209lck, DSSTox_CID_200, AC1L1W6Q, AC1Q7CH3, SCHEMBL7949, WLN: Q2E, DSSTox_RID_75429, DSSTox_GSID_20200, B65586_ALDRICH, KSC270I5D, 442334_SUPELCO, CHEMBL468583, UNII-Z33995S34R, 16140_FLUKA, CTK1H0451, NSC2869, MolPort-001-779-800, BB_SC-7017, NSC-2869, STR01207, Tox21_201036, ANW-31938, BBL027406, RW2124, SBB058668, AKOS000118753, LS-1339, MCULE-5097256006, RP19613, RTR-037031, Z33995S34R, NCGC00091063-01, NCGC00091063-02, NCGC00258589-01, AN-45738, BC207410, BP-21193, CAS-540-51-2, KB-86001, TR-037031, B0590, FT-0611552, ST51037165, X4411, InChI=1/C2H5BrO/c3-1-2-4/h4H,1-2H, 100587-EP2281563A1, 100587-EP2281817A1, 100587-EP2289890A1, 100587-EP2292615A1, 100587-EP2295411A1, 100587-EP2298743A1, 100587-EP2301939A1, 4-01-00-01385 (Beilstein Handbook Reference), A829928, 3B4-0829, I14-0273, I14-7755, 1867-11-4, 29155-34-8

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