Ammonium formate → 5-Methyl-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-3,4-dihydro-2H-1-benzopyran

HRID 1774569Notes

Reaction equation

HRID 1774569 reaction equation
Cl[C:2]1[C:11]2[O:10][CH2:9][CH2:8][CH2:7][C:6]=2[C:5]([CH3:12])=[C:4]([B:13]2[O:17][C:16]([CH3:19])([CH3:18])[C:15]([CH3:21])([CH3:20])[O:14]2)[CH:3]=1.C([O-])=O.[NH4+]>[Pd].CO>[CH3:18][C:16]1([CH3:19])[C:15]([CH3:20])([CH3:21])[O:14][B:13]([C:4]2[CH:3]=[CH:2][C:11]3[O:10][CH2:9][CH2:8][CH2:7][C:6]=3[C:5]=2[CH3:12])[O:17]1

Participants

5

Reactant 2

HCID 2723923Ammonium formateHCID 595785552-(8-Chloro-5-methylchroman-6-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane

Product 1

HCID 574162235-Methyl-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-3,4-dihydro-2H-1-benzopyranYield 94.1%

Reagents, catalysts & solvents 2

HCID 23938PalladiumCatalystHCID 887MethanolSolvent

Procedure

Palladium on activated charcoal (10% Pd by weight, 120 mg) was added to a solution of 2-(8-chloro-5-methyl-3,4-dihydro-2H-1-benzopyran-6-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (7f) (1.20 g, 3.89 mmol) and ammonium formate (2.45 g, 38.89 mmol) in methanol (20 mL). The mixture was refluxed for 60 minutes. The mixture was then cooled to room temperature, filtered through a pad of Celite® and rinsed with methanol. The filtrate was concentrated in vacuo. The residue was dissolved in ethyl acetate (20 mL) and washed with water (20 mL). The organic layer was dried over sodium sulfate, concentrated in vacuo to provide 4,4,5,5-tetramethyl-2-(5-methyl-3,4-dihydro-2H-1-benzopyran-6-yl)-1,3,2-dioxaborolane (7g) (1.00 g, 3.66 mmol, 94%) as a white solid, which was used without further purification.

Workup

  1. temperatureThe mixture was refluxed for 60 minutes
  2. filtrationfiltered through a pad of Celite®
  3. washrinsed with methanol
  4. concentrationThe filtrate was concentrated in vacuo
  5. dissolutionThe residue was dissolved in ethyl acetate (20 mL)
  6. washwashed with water (20 mL)
  7. dry with materialThe organic layer was dried over sodium sulfate
  8. concentrationconcentrated in vacuo

Sources & evidence

ORD record
ord-f0c2069e726b4193b5e3be722436bef4
Source dataset
uspto-grants-2016_02
Patent number
US09260395B2

Reaction notes

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