rac-5-[(3,4-dihydro-6-hydroxy-2,5,7,8-tetramethyl-2H-1-benzopyran-2-yl)ethynyl]-2-hydroxybenzoic acid methyl ester → rac-5-[2-(3,4-Dihydro-6-hydroxy-2,5,7,8-tetramethyl-2H-1-benzopyran-2-yl)ethyl]-2-hydroxybenzoic acid methyl ester

HRID 256865Notes

Reaction equation

HRID 256865 reaction equation
[CH3:1][O:2][C:3](=[O:28])[C:4]1[CH:9]=[C:8]([C:10]#[C:11][C:12]2([CH3:26])[CH2:17][CH2:16][C:15]3[C:18]([CH3:25])=[C:19]([OH:24])[C:20]([CH3:23])=[C:21]([CH3:22])[C:14]=3[O:13]2)[CH:7]=[CH:6][C:5]=1[OH:27]>[Pd].CO>[CH3:1][O:2][C:3](=[O:28])[C:4]1[CH:9]=[C:8]([CH2:10][CH2:11][C:12]2([CH3:26])[CH2:17][CH2:16][C:15]3[C:18]([CH3:25])=[C:19]([OH:24])[C:20]([CH3:23])=[C:21]([CH3:22])[C:14]=3[O:13]2)[CH:7]=[CH:6][C:5]=1[OH:27]

Participants

4

Reactant 1

HCID 15171827rac-5-[(3,4-dihydro-6-hydroxy-2,5,7,8-tetramethyl-2H-1-benzopyran-2-yl)ethynyl]-2-hydroxybenzoic acid methyl ester

Product 1

HCID 15171904rac-5-[2-(3,4-Dihydro-6-hydroxy-2,5,7,8-tetramethyl-2H-1-benzopyran-2-yl)ethyl]-2-hydroxybenzoic acid methyl esterYield 70.7%

Reagents, catalysts & solvents 2

HCID 23938PalladiumCatalystHCID 887MethanolSolvent

Procedure

A mixture of 0.7 g of rac-5-[2-(3,4-dihydro-6-hydroxy-2,5,7,8-tetramethyl-2H-1-benzopyran-2-yl)ethynyl]-2-hydroxybenzoic acid methyl ester, 0.2 g of 5% palladium on carbon and 20 ml of methanol was hydrogenated at atmospheric pressure for 4 hours. The catalyst was separated by filtration and the filtrate was evaporated. The residue was passed over 10 g of silica gel (70-230 mesh) using methylene chloride. The product was crystallized from ether/hexane to give 0.5 g of colorless crystals with m.p. 108°-110°.

Workup

  1. customThe catalyst was separated by filtration
  2. customthe filtrate was evaporated
  3. customThe product was crystallized from ether/hexane

Sources & evidence

ORD record
ord-35ad21c16ff245ecbf64209ecf99e24e
Source dataset
uspto-grants-1993_11
Patent number
US05260294

Reaction notes

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