Trimethyl borate → Benzenepropanoic acid, 4-borono-α,α-dimethyl-

HRID 361469Notizen

Reaktionsgleichung

Reaktionsgleichung von HRID 361469
Br[C:2]1[CH:7]=[CH:6][C:5]([CH2:8][C:9]([C:12]([OH:14])=[O:13])([CH3:11])[CH3:10])=[CH:4][CH:3]=1.C([Li])CCC.[B:20](OC)([O:23]C)[O:21]C>O1CCCC1.CCCCCC>[C:12]([C:9]([CH3:11])([CH3:10])[CH2:8][C:5]1[CH:6]=[CH:7][C:2]([B:20]([OH:23])[OH:21])=[CH:3][CH:4]=1)([OH:14])=[O:13]

Komponenten

6

Edukt 3

HCID 8470Trimethyl borateHCID 211862823-(4-broMophenyl)-2,2-diMethylpropanoic acidHCID 178418339Butyllithium

Produkt 1

HCID 21186231Benzenepropanoic acid, 4-borono-α,α-dimethyl-

Reagenzien, Katalysatoren, Lösungsmittel 2

HCID 8028TetrahydrofuranLösungsmittelHCID 8058HexaneLösungsmittel

Reaktionsbedingungen

Temperatur
-70 °C

Versuchsvorschrift

1-bromo-4-(2-carboxy-2-methylpropyl)benzene (1.93 g) was dissolved in anhydrous tetrahydrofuran (20 ml) and cooled to -70° C. A 1.25M solution of n-butyl lithium in hexane (18 ml) was added dropwise with stirring under an argon atmosphere, such that the temperature did not exceed -65° C. After a further 20 minutes, trimethyl borate was slowly added at -65° C. and the reaction mixture was allowed to attain -15° C. The reaction was quenched by the addition of a saturated aqueous solution of ammonium chloride (50 ml) and the mixture acidified by the addition of 2M hydrochloric acid. The organic phase was separated and the aqueous layer was extracted with ethyl acetate (2×50 ml). The combined organic phase was washed with brine (15 ml) and evaporated and the residue was triturated with hexane to give 4-(2-carboxy-2-methylpropyl)benzeneboronic acid (1.2 g); 1H NMR (DMSO-d6): 1.06 (s, 6 H), 2.78 (s, 2 H), 7.11 (d, 2 H), 7.67 (d, 2 H), 7.9 (br s, 2 H), 12.2 (br s, 1 H); mass spectrum (-ve ESP) 221 (M-H)-.

Aufarbeitung

  1. customdid not exceed -65° C
  2. customto attain -15° C
  3. customThe reaction was quenched by the addition of a saturated aqueous solution of ammonium chloride (50 ml)
  4. additionthe mixture acidified by the addition of 2M hydrochloric acid
  5. customThe organic phase was separated
  6. extractionthe aqueous layer was extracted with ethyl acetate (2×50 ml)
  7. washThe combined organic phase was washed with brine (15 ml)
  8. customevaporated
  9. customthe residue was triturated with hexane

Quellen und Nachweise

ORD-Eintrag
ord-cfae128bc2294d86a992d9f19548c08b
Quelldatensatz
uspto-grants-1999_02
Patentnummer
US05866568

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