(2-METHOXY-1-NAPHTHYL)BORONIC ACID synthesis
- Product Name:(2-METHOXY-1-NAPHTHYL)BORONIC ACID
- CAS Number:104116-17-8
- Molecular formula:C11H11BO3
- Molecular Weight:202.01
121-43-7
3401-47-6
104116-17-8
A tetrahydrofuran (THF, 50 mL) solution of 1-bromo-2-methoxynaphthalene (7.67 g, 32.36 mmol) was slowly added dropwise to a THF solution (15 mL) of magnesium shavings (0.905 g, 37.2 mmol) in a flame-dried reaction vessel protected by argon. The reaction mixture was stirred at room temperature for 2 hours, followed by warming to 50 °C and continued stirring for 1 hour. Upon completion of the reaction, the mixture was cooled to -78 °C and trimethyl borate (11.4 mL, 101.7 mmol) was slowly added. After remaining at -78 °C for 2 h, the reaction mixture was gradually warmed to room temperature and stirred overnight. After addition of water (40 mL), THF was removed by distillation under reduced pressure. the aqueous phase was extracted with dichloromethane, the organic phases were combined and dried over anhydrous magnesium sulfate (MgSO4), filtered and concentrated. The target product 2-methoxy-1-naphthylboronic acid was obtained by recrystallization from dichloromethane as a white powder in 80% yield. The structure of the product was confirmed by 1H NMR (400.14 MHz, CDCl3) and 13C{1H} NMR (75.47 MHz, [D6]DMSO).
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Yield:104116-17-8 86%
Reaction Conditions:
Stage #1: 1-bromo-2-methoxynaphthalenewith magnesium in tetrahydrofuran at 20; for 1 h;Heating;
Stage #2: Triisopropyl borate in tetrahydrofuran at -78 - 20; for 18 h;
Stage #3: with water in tetrahydrofuran; for 1 h;
Steps:
3.2.1 Method 1
Magnesium (5.00g, 0.21mol) was activated by heating and stirring in vacuo for 1h at 80°C after which time it was allowed to cool to room temperature. Dry THF (20mL) was added under an atmosphere of nitrogen. A solution of 1-bromo-2-methoxynaphthalene (10.9g, 46.3mmol) in THF was then added slowly via cannula to give a black suspension. The mixture was heated with a heat gun at regular intervals during the addition period. The solution was then allowed to stir for 1h at room temperature. The resulting mixture was added slowly via cannula to a solution of triisopropylborate (14.6mL, 63.3mmol) in THF (20mL) at -78°C. The reaction mixture was allowed to warm to room temperature while stirring overnight (18h). Water (40mL) was added and the suspension was allowed stir for a further 1h. The reaction mixture was evaporated in vacuo and dichloromethane (100mL) was added. The organic layer was separated, and the aqueous layer was washed with dichloromethane (4×50mL). The combined organic extracts were dried over MgSO4 and filtered. The solvent was removed in vacuo to give a brown solid, which was stirred in pentane overnight producing the title compound 10 (8.04g, 86%) as a white powder. m.p. 116-118°C (lit [45]. m.p. 117-119°C); 1H NMR (300MHz; DMSO-d6) δ=8.27 (s, 2H, B(OH)2), 7.89-7.81 (m, 2H), 7.69 (d, 1H, J=8.3Hz), 7.44-7.28 (m, 3H), and 3.85 (s, OCH3); 13C NMR (75MHz; DMSO-d6) 159.0 (4°), 136.2 (4°), 129.8, 128.9 (4°), 128.4, 127.8 (2C), 126.3, 123.5, 114.1, 56.6 (OMe); IR (KBr) νmax 3350, 1589, 1512, 1333, 1244, and 1063cm-1.
References:
Sweetman, Brian A.;Guiry, Patrick J. [Tetrahedron,2018,vol. 74,# 38,p. 5567 - 5581]
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104116-17-8
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104116-17-8
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104116-17-8
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104116-17-8
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