I know it, this is not the most easy method to make P2P (you first have to prepare phenylacetylchloride from the acid), but because it is an original reaction, I have decided to post it
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First, we acylate the acid chloride with the magnesiumethoxy derivate of diethyl malonate. Then, we do a hydrolysis and decarboxylation of the 2 ester groups to get the methyl ketone.
Procedure:
In a 500 ml three-necked flask equipped with a mercury sealed stirrer, dropping funnel, and reflux condenser protected by a drying tube, was placed 5.35 g (0.22 mole) of magnesium. 5 ml of absolute EtOH and 0.4 ml of CCl4 were added.
The reaction, which started immediately, was allowed to proceed for a few minutes and 75 ml of absolute ether was then added cautiously. The resulting mixture was placed on a steam bath and a solution of 35.2 g (0.22 mole) of diethyl malonate, 20 ml of absolute ethanol and 25 ml of absolute Et2O was added at such a rate that rapid refluxing was maintained, heat being applied when necessary.
The mixture was refluxed for 3 hours, or until the magnesium had dissolved. To the clear solution was added with vigorous stirring (in certain cases a viscous mixture was formed and unless it was stirred vigorously, lower yields were obtained) an etheral solution of 0.20 mole of phenylacetylchloride and the mixture refluxed for 30 minutes. The reaction mixture was cooled and acidified with dillute sulfuric acid. The ether phase, with which an ether extract of the aqueous phase was combined, was washed with water and the solvent distilled.
To the crude diethyl malonate was added a solution of 60 ml of glacial acetic acid, 7.5 ml of concentrated sulfuric acid and 40 ml of wather, and the mixture refluxed for 4 or 5 hours until the decarboxylation was complete.
The reaction mixture was chilled in an ice-bath, made alkaline with 20 % NaOH solution, and extracted with several portions of ether. The combined etheral extracts were washed with water, dried with sodium sulfate followed by drierite, and the solvent distilled.
The residue containing the ketone was distilled in vacuo (97-98.5 °C / 13 mm Hg) or recrystallized.
Yield: 71 %
Ref.: JACS (1946) vol 68 p 1386
I remember that there exists a reaction between an alkyllithium and a lithium salt of a carboxylic acid, but I can't find a refference (I haven't searched very hard at the moment). This should yield the ketone. Can someone help me to find a ref.? Thx
I was thinking about
MeLi + Ph-CH2-COOLi --> P2P