Methyl coumalate is a 2-pyrone and acts as dienophile in Diels-Alder reaction. It reacts with 1,3-butadienes at 100°C to yield tetrahydrocoumarins and 4-methoxycarbonyltricyclo[3.2.1.02,7]octenes. It also reacts with cyclohexadiene to afford tetrahydronaphthalene-2-carboxylate. It undergoes Diels-Alder reaction with unactivated alkenes to afford para-substituted adducts. It has been used as reagent in phosphine-catalyzed [4+3] annulation of modified allylic carbonates. It was also used in the preparation of 7-carboxyquinolizinium derivatives.
Suqing Zheng; Xiyan Lu. Phosphine-catalyzed [4 + 3] annulation for the synthesis of highly functionalized bicyclo[3.2.2]nonadienes. Organic Letters. 2009, 11,(17), 3978-3981.
Richard H.Wiley; Newton R.Smith; Louis H.Knabeschuh. Quinolizinium compounds by cyclization of pyridones from methyl coumalate and β-phenylethylamines. J. Am. Chem. Soc. 1953, 75,(18), 4482-4484.