2-Methylterephthalic acid → 2-carboxy-5-oxo-5H-dibenzo[a,d]cycloheptene

HRID 259503

Reaktionsgleichung

Reaktionsgleichung von HRID 259503
[CH3:1][C:2]1[CH:10]=[C:9]([C:11]([OH:13])=[O:12])[CH:8]=[CH:7][C:3]=1[C:4]([OH:6])=O>CO>[O:6]=[C:4]1[C:3]2[CH:7]=[CH:8][C:9]([C:11]([OH:13])=[O:12])=[CH:10][C:2]=2[CH:1]=[CH:1][C:2]2[CH:10]=[CH:9][CH:8]=[CH:7][C:3]1=2

Komponenten

3

Edukt 1

HCID 2280862-Methylterephthalic acid

Produkt 1

HCID 125630012-carboxy-5-oxo-5H-dibenzo[a,d]cycloheptene

Reagenzien, Katalysatoren, Lösungsmittel 1

HCID 887MethanolLösungsmittel

Versuchsvorschrift

5-Oxo-5H-dibenzo[a,d]cycloheptene-2-carboxylic acid is prepared by esterifying 2-methylterephthalic acid with methanol, in the presence of acid catalyst, to afford the corresponding dimethyl ester which, in turn, is reacted with N-bromosuccinimide to afford 2-bromomethylterephthalic acid dimethyl ester. This diester is reacted with triphenylphosphine to afford 2,5-bis(carbomethoxy)benzyltriphenyl phosphonium bromide which is treated with benzaldehyde and a non-nucleophilic base, such as diazabicylononene, to afford, after alkaline hydrolysis, cis and trans stilbene 2,5-dicarboxylic acid. Hydrogenation of this latter compound with hydrogen over a 5% palladium on carbon catalyst affords 2-(2-phenethyl)terephthalic acid. Treatment with polyphosphoric acid yields 5-oxo-5H-dibenzo[a,d]cycloheptane-2-carboxylic acid which can be recystallized from aqueous dimethylformamide. 5-oxo-5H-dibenzo[a,d]cycloheptene-2-carboxylic acid is prepared by successively treating 5-oxo-5H-dibenzo[a,d]cycloheptane-2-carboxylic acid with diazomethane, N-bromosuccinimide, and dimethylformamide/diazabicyclononene, followed by base hydrolysis and acidification.

Quellen und Nachweise

ORD-Eintrag
ord-3dd634edde1848818245498a65a51fb1
Quelldatensatz
uspto-grants-1977_07
Patentnummer
US04038299

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