Trimethyl borate → (2-(Benzyloxy)naphthalen-1-yl)boronic acid

HRID 352023

Reaction equation

HRID 352023 reaction equation
Br[C:2]1[C:11]2[C:6](=[CH:7][CH:8]=[CH:9][CH:10]=2)[CH:5]=[CH:4][C:3]=1[O:12][CH2:13][C:14]1[CH:19]=[CH:18][CH:17]=[CH:16][CH:15]=1.[Li]CCCC.[B:25](OC)([O:28]C)[O:26]C>CCOCC>[C:14]1([CH2:13][O:12][C:3]2[CH:4]=[CH:5][C:6]3[C:11](=[CH:10][CH:9]=[CH:8][CH:7]=3)[C:2]=2[B:25]([OH:28])[OH:26])[CH:19]=[CH:18][CH:17]=[CH:16][CH:15]=1

Participants

5

Reactant 3

HCID 8470Trimethyl borateHCID 3788832-Benzyloxy-1-bromonaphthaleneHCID 178418339Butyllithium

Product 1

HCID 22715022(2-(Benzyloxy)naphthalen-1-yl)boronic acidYield 83.1%

Reagents, catalysts & solvents 1

HCID 3283Diethyl EtherSolvent

Conditions

Temperature
0 °C

Procedure

To a suspension of 1-bromo-2-(phenylmethoxy)naphthalene (6.26 g, 20.0 mmol) in Et2O (75 mL) at −78° C. was added n-BuLi (8.0 mL, 2.5 M, 20 mmol) in hexanes and the mixture was stirred at 0° C. for 1 h. After re-cooling to −78° C., the mixture was treated with trimethyl borate (2.5 mL, 22 mmol) and allowed to warm to room temperature overnight. The resulting mixture was quenched with 1 M HCl (50 mL) and stirred at room temperature for 45 min. The phases were separated and the extraction was completed with CH2Cl2. The combined organic extracts were dried (MgSO4) and evaporated in vacuo to give the title compound, 2-(phenylmethoxy)-1-napthaleneboronic acid as a white powder (4.62 g, 83%), which was used in the next step without further purification. For analytical purposes, a small amount of the product was re-crystallised from MeOH/H2O: mp 133.0-135.0° C. (MeOH/H2O); 1H NMR (250 MHz, d4-MeOH) δ5.20 (s, 2H), 7.28-7.60 (m, 9H), and 7.56-7.88 (m, 2H); 13C NMR (63 MHz, d4-MeOH) δ71.95, 115.4, 124.8, 127.7 (2C), 128.4, 128.9, 129.5, 129.6, 130.7 (2C?), 131.8, 137.2, 139.0 and 159.7;i IR (CHCl3) νmax 3609, 3490, 1592, 1509, 1386, and 1332 cm−1; MS (EI+) m/z (rel intensity) 278 (10%, M+), 234 (10), and 91 (100); HRMS calcd for C17H15BO3 (M+) 277.1151, found 277.1163. Anal. Calcd for C17H15BO3: C, 73.42; H, 5.44. Found: C, 73.07; H, 5.33.

Workup

  1. temperatureAfter re-cooling to −78° C.
  2. temperatureto warm to room temperature overnight
  3. customThe resulting mixture was quenched with 1 M HCl (50 mL)
  4. stirringstirred at room temperature for 45 min
  5. customThe phases were separated
  6. extractionthe extraction
  7. dry with materialThe combined organic extracts were dried (MgSO4)
  8. customevaporated in vacuo

Sources & evidence

ORD record
ord-e1548cd83be642968594425b9f17e593
Source dataset
uspto-grants-2004_06
Patent number
US06743922B2

Linked notes

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