Triphenylphosphine → Phosphonium, [[3-(methoxycarbonyl)phenyl]methyl]triphenyl-, bromide
Reaktionsgleichung
[Br:1][CH2:2][C:3]1[CH:4]=[C:5]([CH:10]=[CH:11][CH:12]=1)[C:6]([O:8][CH3:9])=[O:7].[C:13]1([P:19]([C:26]2[CH:31]=[CH:30][CH:29]=[CH:28][CH:27]=2)[C:20]2[CH:25]=[CH:24][CH:23]=[CH:22][CH:21]=2)[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=1>C1(C)C(C)=CC=CC=1>[Br-:1].[CH3:9][O:8][C:6]([C:5]1[CH:4]=[C:3]([CH:12]=[CH:11][CH:10]=1)[CH2:2][P+:19]([C:20]1[CH:21]=[CH:22][CH:23]=[CH:24][CH:25]=1)([C:26]1[CH:31]=[CH:30][CH:29]=[CH:28][CH:27]=1)[C:13]1[CH:14]=[CH:15][CH:16]=[CH:17][CH:18]=1)=[O:7]Komponenten
4
Edukt 2
Produkt 1
Reagenzien, Katalysatoren, Lösungsmittel 1
Versuchsvorschrift
The preparation of begins with the known methyl 3-(bromomethyl)benzoate. This halide is heated in xylene solution with triphenylphosphine to yield (3-methoxycarbonylbenzyl)triphenylphosphonium bromide. The phosphonium salt is converted to the ylide with sodium ethoxide and the ylide caused to react with acetaldehyde to yield ethyl 3-(1-propenyl)benzoate. (Note that the ethyl ester has been obtained as a result of transesterification with solvent ethanol.) The ester is heated with N-bromosuccinimide in carbon tetrachloride for an extended period to yield ethyl 3-(3-bromo-1-propenyl)benzoate. This compound is treated with the anion derived from methyl methylthiomethyl sulfoxide as described in section (b) above. The resulting dimethylmercaptal S-oxide is hydrolyzed with acid catalysis to ethyl 3-(4-oxo-1-butenyl)benzoate. Hydrogenation of this olefinic aldehyde over a palladium catalyst affords the aldehyde intermediate XXIII.