Patent US4936966 (http://l2.espacenet.com/dips/viewer?PN=US4936966&CY=gb&LG=en&DB=EPD)
. If you used a mixture of benzyl chloride and excess methyl chloride (or other halide) maybe you could get a good yield of P2P from the benzyl chloride. Also seePatent US4629541 (http://l2.espacenet.com/dips/viewer?PN=US4629541&CY=gb&LG=en&DB=EPD)
.Tetrahedron Letters 35(2), 203-206 (1994) (https://www.thevespiary.org/rhodium/Rhodium/pdf/p2p.paa-meli-cecl3.pdf)
(https://www.thevespiary.org/rhodium/Rhodium/pdf/p2p.paa-meli-cecl3.pdf)Experimental
Methyl lithium (1 equivalent) is added to a solution of phenylacetic acid in anhydrous THF at -78°C and stirred for 15 min to form a suspension of lithium phenylacetate. A suspension of CeCl3 (2 Eq.) in THF* at -78°C is added to the solution and the resulting mixture stirred for 30 min at -78°C. Methyl lithium (1 equivalent) is added dropwise and the mixture stirred for 16 hours, after which time the reaction was quenched by the dropwise addition of 5% aqueous HCl at -78°C. Standard workup gave phenyl-2-propanone in 62% (isolated) yield, with negligible formation of any tertiary alcohol and the remainder being mostly unreacted starting material.
* CeCl3·7H2O (Aldrich) is dried by stirring the material for two hours in a flask at 180°C/0.4 mmHg pressure. A suspension in anhydrous THF is stirred at ambient temperature for at least 3 h before use.