Thallous salts of .beta.-dicarbonyl compounds, prepared by reaction of the .beta.-dicarbonyl compounds with a thallous alkoxide, are treated with alkyl halides to give C-alkyl products in high yield, with acyl halides at room temperature to give C-acyl products, and with acyl halides at low temperatures to give O-acyl products. Thallous phenolates are esterified with acyl or aroyl halides. Anhydrides are also prepared, as are biaryls and bi-sec-alkyls. N-heterocyclics, including purines and pyrimidines, are N-alkylated. Lactams are O-acylated or N-alkylated.