Methyl chloroformate → 2,2-dimethyl-1-benzothiophen-3(2H)-one 1,1-dioxide

HRID 2089504Notes

Reaction equation

HRID 2089504 reaction equation
[CH3:1][CH:2]([S:4]([C:7]1[CH:12]=[CH:11][CH:10]=[CH:9][CH:8]=1)(=[O:6])=[O:5])[CH3:3].C([Li])CCC.CO[C:20](Cl)=[O:21]>C1COCC1>[CH3:1][C:2]1([CH3:3])[S:4](=[O:5])(=[O:6])[C:7]2[CH:12]=[CH:11][CH:10]=[CH:9][C:8]=2[C:20]1=[O:21]

Participants

5

Reactant 3

HCID 6586Methyl chloroformateHCID 199476((1-Methylethyl)sulfonyl)benzeneHCID 178418339Butyllithium

Product 1

HCID 110310922,2-dimethyl-1-benzothiophen-3(2H)-one 1,1-dioxide

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent

Procedure

To a solution of (propane-2-sulfonyl)-benzene (CAS#4238-09-9), which can be prepared as described in Cram, D. J. et al. Journal of the American Chemical Society, 1967, 89, 2072-2077, (1.18 g, 6.4 mmol) in THF (60 mL) at 0° C. is added a 2.5 M solution of n-butyl lithium in hexanes (5.8 mL, 14.7 mmol). The reaction is slowly warmed to room temperature over an hour, at which time it is re-cooled to −78° C. and methylchloroformate (0.74 mL, 9.6 mmol) is added. The reaction is brought to room temperature and permitted to stir for 16 hours. The reaction is then quenched with saturated aqueous NH4Cl and diluted with ethyl acetate. The layers are separated and the aqueous layer is extracted twice with ethyl acetate. The organic layers are combined, dried with Na2SO4, filtered, and concentrated. The resulting residue is purified by silica gel flash chromatography (ethyl acetate-heptane, 0:1 to 1:4) to provide 2,2-dimethyl-1,1-dioxo-1,2-dihydro-1lambda*6*-benzo[b]thiophen-3-one. 1H NMR (400 MHz, CDCl3) δ ppm 1.63 (s, 6 H), 7.79-7.86 (m, 1 H), 7.92-7.99 (m, 1 H), 8.03 (d, J=8.1 Hz, 2 H).

Workup

  1. temperatureis re-cooled to −78° C.
  2. customis brought to room temperature
  3. customThe reaction is then quenched with saturated aqueous NH4Cl
  4. additiondiluted with ethyl acetate
  5. customThe layers are separated
  6. extractionthe aqueous layer is extracted twice with ethyl acetate
  7. dry with materialdried with Na2SO4
  8. filtrationfiltered
  9. concentrationconcentrated
  10. customThe resulting residue is purified by silica gel flash chromatography (ethyl acetate-heptane, 0:1 to 1:4)

Sources & evidence

ORD record
ord-abbc6f889f7645259a3652b4e5649992
Source dataset
uspto-grants-2013_05
Patent number
US08436035B2

Reaction notes

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