Sulfuric Acid → 2-(methylsulfanyl)-6-(3,5-dimethoxyphenyl)-8-ethyl-8H-pyrido[2,3-d]pyrimidin-7-one

Participants

Reaction Steps

A mixture of the product of Example 5, N-[6-(3,5dimethoxy-phenyl)-8-ethyl-2-methylsulfanyl-8H-pyrido[2,3-d]pyrimidin-7-ylidene]-acetamide, (43.5 g, 0.11 mol) and dioxane (200 mL) was heated with stirring to the boiling point at which point the solid dissolved. At the boiling point was added 100 mL of 15% aq. H2SO4 and the mixture refluxed for 2 minutes. The reaction mixture cooled in an ice bath and water was added (˜200 mL). Crystals formed that were collected by filtration and washed with water. The solid was dissolved in CH2Cl2 (400 mL), dried over K2CO3, charcoal added, and the mixture filtered through celite. The filtrate was evaporated under reduced pressure to give 33.0 g of the titled compound. mp 120–122° C.

Provenance & Evidence