Hydrochloric Acid → 5,8-Dimethyl-6-bromothiochroman-4-one

HRID 1602769Notes

Reaction equation

HRID 1602769 reaction equation
[CH3:1][C:2]1[C:7]2[C:8](=[O:12])[CH2:9][CH2:10][S:11][C:6]=2[C:5]([CH3:13])=[CH:4][CH:3]=1.[Cl-].[Al+3].[Cl-].[Cl-].[Br:18]Br.Cl>C(Cl)Cl.O>[Br:18][C:3]1[CH:4]=[C:5]([CH3:13])[C:6]2[S:11][CH2:10][CH2:9][C:8](=[O:12])[C:7]=2[C:2]=1[CH3:1]

Participants

7

Reactant 4

HCID 313Hydrochloric AcidHCID 24408BromineHCID 6451240Aluminum(III) ChlorideHCID 216965945,8-Dimethyl-3,4-dihydro-2H-1-benzothiopyran-4-one

Product 1

HCID 152784955,8-Dimethyl-6-bromothiochroman-4-oneYield 46%

Reagents, catalysts & solvents 2

HCID 962WaterSolventHCID 6344DichloromethaneSolvent2×

Procedure

A solution of 4.07 g (0.021 mol) of the title compound of Step B in 25 mL of methylene chloride was added dropwise to a mixture of 7.07 g (0.053 mol) of aluminum chloride (purchased from Aldrich Chemical Company) and 25 mL of methylene chloride. The suspension was stirred for approximately 15 minutes, 1.14 mL (0.022 mol) of bromine (purchased from Janssen) was added dropwise and the mixture was refluxed for 10 minutes. The hot mixture was poured into 10 mL of concentrated hydrochloric acid containing 75 g of ice, stirred for 10 minutes, diluted with 50 mL of water, and extracted with diethyl ether (2×200 mL). The organic layer was washed with water (2×200 mL), dried (Na2SO4), filtered and evaporated to dryness. The crude product was chromatographed over silica gel eluting with ethyl acetate:hexane (5% 95%) to yield 2.62 g of the title compound of Step C as a solid melting at 87-88° C. 1H NMR (CDCl3): δ2.3 (s,3H), 2.6 (s,3H), 3.0 (m,2H), 3.2 (m,2H), 7.45 (s,1H).

Workup

  1. temperaturethe mixture was refluxed for 10 minutes
  2. stirringstirred for 10 minutes
  3. extractionextracted with diethyl ether (2×200 mL)
  4. washThe organic layer was washed with water (2×200 mL)
  5. dry with materialdried (Na2SO4)
  6. filtrationfiltered
  7. customevaporated to dryness
  8. customThe crude product was chromatographed over silica gel eluting with ethyl acetate

Sources & evidence

ORD record
ord-3dcccd953da047688facbf58da124314
Source dataset
uspto-grants-1999_11
Patent number
US05985799

Reaction notes

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