I found it:
The Alkylation of PhenylacetonesBY EVERETT M. SCHULTZ, JOHN B. BICKING, SALLY MICKEY AND FRANK S. CROSSLEYJ.A.C.S. vol. 75, pp.1072-1074 (1953)The synthesis of alkylated derivatives of phenylacetone and diphenylacetone was investigated. In the presence of powdered sodium hydroxide, phenylacetone reacts with normal and selected branched-chain lower-alkyl halides to produce 1-alkyl-1-phenylacetones in good yields. 1-Alkyl-1,1-diphenylacetones have been prepared by treating 1-bromo-1-alkyl-1-phenylacetones with benzene and anhydrous aluminum chloride or, in some cases, by direct alkylation of diphenylacetone with an alkyl halide in the presence of potassium t-butoxide or sodium hydroxide.