Cesium carbonate → Ethyl 2-(1-hydroxy-4-methyl-6-(5-nitro-1,3,4-thiadiazol-2-yloxy)-1,3-dihydrobenzo[c][1,2]oxaborol-3-yl)acetate

HRID 1798296Notes

Reaction equation

HRID 1798296 reaction equation
[OH:1][B:2]1[C:6]2[CH:7]=[C:8]([OH:12])[CH:9]=[C:10]([CH3:11])[C:5]=2[CH:4]([CH2:13][C:14]([O:16][CH2:17][CH3:18])=[O:15])[O:3]1.Br[C:20]1[S:21][C:22]([N+:25]([O-:27])=[O:26])=[N:23][N:24]=1.C([O-])([O-])=O.[Cs+].[Cs+]>C(#N)C>[OH:1][B:2]1[C:6]2[CH:7]=[C:8]([O:12][C:20]3[S:21][C:22]([N+:25]([O-:27])=[O:26])=[N:23][N:24]=3)[CH:9]=[C:10]([CH3:11])[C:5]=2[CH:4]([CH2:13][C:14]([O:16][CH2:17][CH3:18])=[O:15])[O:3]1

Participants

5

Reactant 3

HCID 10796Cesium carbonateHCID 122078702-Bromo-5-nitro-1,3,4-thiadiazoleHCID 58292549Ethyl 2-(1,6-dihydroxy-4-methyl-1,3-dihydrobenzo[c][1,2]oxaborol-3-yl)acetate

Product 1

HCID 58292621Ethyl 2-(1-hydroxy-4-methyl-6-(5-nitro-1,3,4-thiadiazol-2-yloxy)-1,3-dihydrobenzo[c][1,2]oxaborol-3-yl)acetateYield 36%

Reagents, catalysts & solvents 1

HCID 6342AcetonitrileSolvent2×

Conditions

Temperature
-25 °C

Procedure

To a stirred solution of ethyl 2-(1,6-dihydroxy-4-methyl-1,3-dihydrobenzo[c][1,2]oxaborol-3-yl)acetate (43 g, 0.17 mol) in anhydrous acetonitrile (2000 mL) at −20° C. was added a solution of 2-bromo-5-nitro-1,3,4-thiadiazole (70 g, 0.33 mol.) in acetonitrile (1000 mL). Then Cs2CO3 (166 g, 0.51 mol, 3 eq.) as added portionwise at this temperature. The mixture was stirred at −20 to −30° C. for 20 hrs. Then, the reaction mixture was allowed to warm to r.t. and stirred at this temperature for 15 h. After filtration, the filtrate was concentrated and acidified to pH=2 at 0° C. with diluted hydrochloric acid. The mixture was extracted with EtOAc and the organic extracts were washed with brine, dried over sodium sulfate and concentrated in vacuo The residue was purified by chromatography on silica gel column (petroleum ether/EtOAc/AcOH, gradient elution) to give the ethyl 2-(1-hydroxy-4-methyl-6-(5-nitro-1,3,4-thiadiazol-2-yloxy)-1,3-dihydrobenzo[c][1,2]oxaborol-3-yl)acetate as a yellow solid (23 g, 36% yield).

Workup

  1. temperatureto warm to r.t.
  2. stirringstirred at this temperature for 15 h
  3. filtrationAfter filtration
  4. concentrationthe filtrate was concentrated
  5. customacidified to pH=2 at 0° C. with diluted hydrochloric acid
  6. extractionThe mixture was extracted with EtOAc
  7. washthe organic extracts were washed with brine
  8. dry with materialdried over sodium sulfate
  9. concentrationconcentrated in vacuo The residue
  10. customwas purified by chromatography on silica gel column (petroleum ether/EtOAc/AcOH, gradient elution)

Sources & evidence

ORD record
ord-fba2969565064ccaacf4b164b2616c82
Source dataset
uspto-grants-2013_01
Patent number
US08343944B2

Reaction notes

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