A mixture of 0.113 g (0.29 mmol) of 6-(2,6-dichlorophenyl)-2-methanesulfonyl-8-methyl-8H-pyrido[2,3-d]pyrimidin-7-one of Example 39 and 0.50 g (3.70 mmol) of 3,4-methylenedioxyaniline was heated, with stirring, in a 200° C. oil bath. The resulting solution was heated for 5 minutes and cooled to room temperature. Ethyl acetate (2 mL) was added, and some traces of solids were filtered. The crystals that slowly developed in the filtrate were filtered and washed with 2 mL of ethyl acetate; wt 0.080 g. The solid was purified to remove dark colors by silica gel chromatography, eluting with chloroform and then 50% hexane/ethyl acetate to obtain pure crystalline product; wt 0.054 g; mp 240°-241° C.
