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1,5-Dibromopentane → (R)-(+)-6-[(5-bromopentyl)oxy]-3,4-dihydro-2,5,7,8-tetramethyl-2H-1-benzopyran-2-carboxylic acid methyl ester

HRID 2232495
Notizen
Druckvorschau

Reaktionsgleichung

Reaktionsgleichung von HRID 2232495
[CH3:1][O:2][C:3]([C@@:5]1([CH3:19])[CH2:10][CH2:9][C:8]2[C:11]([CH3:18])=[C:12]([OH:17])[C:13]([CH3:16])=[C:14]([CH3:15])[C:7]=2[O:6]1)=[O:4].C(=O)([O-])[O-].[K+].[K+].C1OCCOCCOCCOCCOCCOC1.[Br:44][CH2:45][CH2:46][CH2:47][CH2:48][CH2:49]Br>O.CCOCC.C(#N)C>[CH3:1][O:2][C:3]([C@@:5]1([CH3:19])[CH2:10][CH2:9][C:8]2[C:11]([CH3:18])=[C:12]([O:17][CH2:49][CH2:48][CH2:47][CH2:46][CH2:45][Br:44])[C:13]([CH3:16])=[C:14]([CH3:15])[C:7]=2[O:6]1)=[O:4]
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Komponenten

8

Edukt 4

HCID 81001,5-DibromopentaneHCID 11430Potassium CarbonateHCID 2855718-Crown-6HCID 14308591(R)-(+)-methyl 3,4-dihydro-6-hydroxy-2,5,7,8-tetramethyl-2H-1-benzopyran-2-carboxylate

Produkt 1

HCID 14329716(R)-(+)-6-[(5-bromopentyl)oxy]-3,4-dihydro-2,5,7,8-tetramethyl-2H-1-benzopyran-2-carboxylic acid methyl ester

Reagenzien, Katalysatoren, Lösungsmittel

3
HCID 962WaterLösungsmittelHCID 3283Diethyl EtherLösungsmittelHCID 6342AcetonitrileLösungsmittel

Versuchsvorschrift

A mixture of 6.5 g (24.6 mmoles) of (R)-(+)-6-hydroxy-3,4-dihydro-2,5,7,8-tetramethyl-2H-1-benzopyran-2-carboxylic acid methyl ester, 10.37 g (75.1 mmoles) of anhydrous potassium carbonate, 1.12 g of 18-crown-6, 39.3 ml (0.2 mole) of 1,5-dibromopentane, and 150 ml of acetonitrile was stirred and refluxed for 21 hours. After being cooled, the mixture was treated with ether and water. The organic layer was separated, washed with water and brine, dried over anhydrous magnesium sulfate, filtered and concentrated under reduced pressure. The residue (68 g) was purified first by column chromatography on silica gel (400 g; eluting with 49:1 toluene-ethyl acetate) and then by preparative HPLC on silica gel using 9:1 hexane-ethyl acetate as the mobile phase. There was obtained 9.71 g (95.6%) or (R)-(+)-6-[(5-brompentyl)oxy]-3,4-dihydro-2,5,7,8-tetramethyl-2H-1-benzopyran-2-carboxylic acid methyl ester as a solid. Recrystallization from ethanol gave a colorless solid mp 64°- 65.5° C., [α]D25 +36.37° (c 2, CHCl3).

Aufarbeitung

  1. temperaturerefluxed for 21 hours
  2. temperatureAfter being cooled
  3. customThe organic layer was separated
  4. washwashed with water and brine
  5. dry with materialdried over anhydrous magnesium sulfate
  6. filtrationfiltered
  7. concentrationconcentrated under reduced pressure
  8. customThe residue (68 g) was purified first by column chromatography on silica gel (400 g; eluting with 49:1 toluene-ethyl acetate)

Quellen und Nachweise

ORD-Eintrag
ord-a7ff44945d974caabaee27066cec27cc
Quelldatensatz
uspto-grants-1988_11
DOI
10.6084/m9.figshare.5104873.v1
Patentnummer
US04788214

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