Diels-Alder cycloadditions of 2(1H)-quinolones having an electron-withdrawing group at the 3-position with alkyl- and silyloxy-1, 3-butadienes (2a, b) were carried out to give phenanthridones richly functionalized regio- or stereoselectively under conditions of atmospheric and high pressure. Furthermore, regioselectivity and chemoselectivity of 3-substituted 2(1H)-quinolones to 2a, b were examined using MO calculation.