Quinizarin → 1,4-Anthraquinone

HRID 2306895

Reaction equation

HRID 2306895 reaction equation
C[O:2][C:3]1[C:16]2[C:7](=[CH:8][C:9]3[C:14]([CH:15]=2)=[CH:13][CH:12]=[CH:11][CH:10]=3)[C:6]([O:17]C)=[CH:5][CH:4]=1.C1C=CC2C(=O)C3C(=C(O)C=CC=3O)C(=O)C=2C=1.[BH4-].[Na+]>COCCOCCOC.CO>[C:3]1(=[O:2])[C:16]2[C:7](=[CH:8][C:9]3[C:14]([CH:15]=2)=[CH:13][CH:12]=[CH:11][CH:10]=3)[C:6](=[O:17])[CH:5]=[CH:4]1

Participants

6

Reactant 3

HCID 6688QuinizarinHCID 831071,4-DimethoxyanthraceneHCID 4311764Sodium borohydride2×

Product 1

HCID 694571,4-AnthraquinoneYield 95%

Reagents, catalysts & solvents 2

HCID 887MethanolSolventHCID 8150DiglymeSolvent

Procedure

Although the preparation of 1,4-dimethoxyanthracene (1) has been reported (Criswell, et al., J. Org. Chem. 1974, 39, 770-774) by using methylation of quinizarin (3) followed by sequential reduction of the diketo function with sodium borohydride in diglyme, the difficulty in the reduction steps prompted us to investigate an easier method in the preparation of 1. Reduction of 3 with sodium borohydride in MeOH followed by quenching with HCl gave a 95% yield of 1,4-anthraquinone (4) (Scheme 2). Reduction of the quinone moiety of 4 with aqueous sodium hydrosulfite in 1,4-dioxane provided 1,4-dihydroxyanthracene (5). Methylation of 5 with sodium hydride in DMF at room temperature gave excellent yield of 1.

Workup

  1. customin the preparation of 1
  2. customby quenching with HCl

Sources & evidence

ORD record
ord-2846e1f06cac499386558423024d60af
Source dataset
uspto-grants-2004_12
Patent number
US06828450B2

Linked notes

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