ChemicalBook CAS DataBase List 3,4-dihydro-2H-1,4-benzoxazin-6-ol

3,4-dihydro-2H-1,4-benzoxazin-6-ol synthesis

9synthesis methods

Product Name:3,4-dihydro-2H-1,4-benzoxazin-6-ol
CAS Number:26021-57-8
Molecular formula:C8H9NO2
Molecular Weight:151.16

53412-38-7

26021-57-8

General procedure for the synthesis of 3,4-dihydro-2H-benzo[b][1,4]oxazin-6-ol from 6-hydroxy-2H-benzo[b][1,4]oxazin-3(4H)-one: 6-Hydroxy-2H-benzo[b][1,4]oxazin-3(4H)-one (0.39 g, 2.35 mmol) was dissolved in tetrahydrofuran (THF) and at 0 °C 1 M borane-THF solution (7.05 mL, 7.05 mmol) was slowly added dropwise for a controlled time of 5 min. After the dropwise addition, the reaction mixture was gradually warmed to room temperature and stirred overnight. Upon completion of the reaction, the excess borane was quenched by careful addition of methanol. Subsequently, the solvent was removed by distillation under reduced pressure and the crude product was extracted with ethyl acetate (EtOAc) to afford pure 3,4-dihydro-2H-benzo[b][1,4]oxazin-6-ol as an oil in quantitative yield (0.34 g). The product was confirmed by nuclear magnetic resonance hydrogen spectroscopy (1H NMR, DMSO-d6): δ 8.48 (s, 1H), 6.37 (d, 1H, J = 8.47 Hz), 5.96 (d, 1H, J = 2.75 Hz), 5.82 (dd, 1H, J = 8.44, 2.76 Hz), 3.97 (t, 2H, J = 4.38 Hz), 3.18 ( t, 2H, J = 4.31 Hz). Nuclear magnetic resonance carbon spectrum (13C NMR, DMSO-d6): δ 152.2, 136.6, 135.8, 116.7, 103.8, 102.0, 65.0, 47.2. electrospray high-resolution mass spectrometry (ES-HRMS) measured [M + H]+ as 152.0711, which is in accordance with the theoretically calculated value (C8H10NO2).

53412-38-7
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$65.00/100mg

26021-57-8
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$72.00/100mg

Yield:26021-57-8 100%

Reaction Conditions:

with borane-THF in tetrahydrofuran at 0 - 20;

Steps:

d
Compound 48 (0.39 g, 2.35 mmol) was dissolved in THF and IM BH₃-THF (7.05 ml, 7.05 mmol) was added to the reaction mixture at 0 ⁰C slowly over a time of 5 min. After the addition the reaction mixture was warmed to the room temperature and left overnight. Excess borane was destroyed by careful addition of methanol. The solvent was removed and the crude reaction mixture was extracted in EtOAc to give an oily pure compound in quantitative yield (0.34 g.). ¹H NMR(dmso-d₆): 8.48 (s, IH), 6.37 (d, IH, J=8.47 Hz), 5.96 (d, IH, J=2.75 Hz), 5.82 (dd, IH, J=8.44, 2.76 Hz), 3.97 (t, 2H, J=4.38 Hz), 3.18 (t, 2H, J=4.31 Hz). ¹³C NMR (dmso-d6): 152.2, 136.6, 135.8, 116.7, 103.8, 102.0, 65.0, 47.2. ES- HRMS [M+H]⁺ 152.0711. Calcd for (C₈Hi₀NO₂): 152.0711

References:

UNIVERSITY OF MASSACHUSETTS WO2009/36351, 2009, A2 Location in patent:Page/Page column 21; 22/24

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