Sulfuric Acid → 4-(4-Bromo-2-ethylphenyl)-2,6-diethyl-2,6-dimethylpyran-3,5-dione

HRID 341672Notes

Reaction equation

[Br:1][C:2]1[CH:7]=[CH:6][C:5]([CH:8]2[C:10]3([C:14](=[O:15])[C:13]([CH2:17][CH3:18])([CH3:16])[O:12][C:11]3([CH2:20][CH3:21])[CH3:19])[O:9]2)=[C:4]([CH2:22][CH3:23])[CH:3]=1.S(=O)(=O)(O)O>ClCCl>[Br:1][C:2]1[CH:7]=[CH:6][C:5]([CH:8]2[C:14](=[O:15])[C:13]([CH2:17][CH3:18])([CH3:16])[O:12][C:11]([CH2:20][CH3:21])([CH3:19])[C:10]2=[O:9])=[C:4]([CH2:22][CH3:23])[CH:3]=1

Participants

Conditions

Temperature: 7.5 °C

Procedure

To an ice cold solution of 2-(4-bromo-2-ethylphenyl)-4,6-diethyl-4,6-dimethyl-1,5-dioxaspiro[2.4]heptan-7-one (15 g, 0.0397 mol) in dichloromethane (7.5 ml) is added concentrated sulphuric acid (45 ml), dropwise over 50-60 minutes, maintaining the temperature of the reaction mixture at 5-10° C. The reaction mixture is maintained at 5-10° C. for 10-15 minutes, quenched into crushed ice (225 g) and extracted with dichloromethane (3×100 ml). The organic phases are combined, washed with water, and dried over anhydrous sodium sulfate. The mixture is filtered, and the filtrate is evaporated under reduced pressure. The residue is purified by column chromatography on silica gel to give 4-(4-bromo-2-ethylphenyl)-2,6-diethyl-2,6-dimethylpyran-3,5-dione (2 g) as a white solid.

Workup

temperatureThe reaction mixture is maintained at 5-10° C. for 10-15 minutes
customquenched
custominto crushed ice (225 g)
extractionextracted with dichloromethane (3×100 ml)
washwashed with water
dry with materialdried over anhydrous sodium sulfate
filtrationThe mixture is filtered
customthe filtrate is evaporated under reduced pressure
customThe residue is purified by column chromatography on silica gel

Sources & evidence

ORD record: ord-df99c1ae7da04a8588d08dd1553b2b60
Source dataset: uspto-grants-2014_11
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08895761B2

Reaction notes

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