tert-Butyl acetate → 2-Bromo-3',4'-bis(pivaloyloxy)acetophenone

HRID 905292

Reaktionsgleichung

Reaktionsgleichung von HRID 905292
[Br:1]Br.[C:3]([O:9][C:10]1[CH:11]=[C:12]([C:23](=[O:25])[CH3:24])[CH:13]=[CH:14][C:15]=1[O:16][C:17](=[O:22])[C:18]([CH3:21])([CH3:20])[CH3:19])(=[O:8])[C:4]([CH3:7])([CH3:6])[CH3:5].C(OC(C)(C)C)(=O)C.[Cl-].[Al+3].[Cl-].[Cl-]>C(Cl)(Cl)Cl>[Br:1][CH2:24][C:23]([C:12]1[CH:13]=[CH:14][C:15]([O:16][C:17](=[O:22])[C:18]([CH3:21])([CH3:20])[CH3:19])=[C:10]([O:9][C:3](=[O:8])[C:4]([CH3:7])([CH3:6])[CH3:5])[CH:11]=1)=[O:25]

Komponenten

6

Edukt 4

HCID 10908tert-Butyl acetateHCID 24408BromineHCID 6451240Aluminum(III) ChlorideHCID 128761863',4'-Bis(pivaloyloxy)acetophenone

Produkt 1

HCID 128761872-Bromo-3',4'-bis(pivaloyloxy)acetophenone

Reagenzien, Katalysatoren, Lösungsmittel 1

HCID 6212ChloroformLösungsmittel2×

Versuchsvorschrift

A solution of bromine (3.15 ml., 0.061 mole) in chloroform (50 ml.) was added dropwise at room temperature to a stirred solution of 3',4'-bis(pivaloyloxy)acetophenone (19.5 g., 0.061 mole) and t-butyl acetate (8.2 ml., 0.06 mole) in chloroform (150 ml.) containing a catalytic amount of anhydrous aluminium chloride (0.2 g.). The reaction mixture was stirred at room temperature for 1 hour after the addition was complete, chromatographic silica gel (75 g.) was then added and the mixture evaporated in vacuo. The residual solid was added to the top of a column of dry chromatographic silica-gel (1 kg., previously deactivated by addition of 10% w/w water and then equilibrated with 10% v/w of a 5% v/v solution of ethyl acetate in toluene). The column was developed by elution with a 5% v/v solution (1.1 l.) of ethyl acetate in toluene. The column was then eluted with ethyl acetate (2×500 ml.) and the fractions collected were monitored by thin layer chromatography (TLC) (on silica plates developed in a 50% v/v mixture of ethyl acetate and toluene). The later fractions were combined and evaporated to give 2-bromo-3',4'-bis(pivaloyloxy)acetophenone as an oil (14.2 g.) which rapidly crystallised to give a solid of m.p. 64°-66° C.

Aufarbeitung

  1. additionafter the addition
  2. additionchromatographic silica gel (75 g.) was then added
  3. customthe mixture evaporated in vacuo
  4. additionThe residual solid was added to the top of a column of dry chromatographic silica-gel (1 kg
  5. addition, previously deactivated by addition of 10% w/w water
  6. washThe column was developed by elution with a 5% v/v solution (1.1 l.) of ethyl acetate in toluene
  7. washThe column was then eluted with ethyl acetate (2×500 ml.)
  8. customthe fractions collected
  9. additiondeveloped in a 50% v/v mixture of ethyl acetate and toluene)
  10. customevaporated

Quellen und Nachweise

ORD-Eintrag
ord-c2986c0e7e044cc2bc697569c2f159bb
Quelldatensatz
uspto-grants-1983_12
Patentnummer
US04423070

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