Use of 4-Cyanocoumarins as Dienophiles in a Facile Synthesis of Highly Substituted Dibenzopyranones JungMichael E. AllenDamian A. 2009 A new synthesis of dibenzopyranones <b>14</b> is reported via the Dielsāˆ’Alder cycloaddition of 4-cyanocoumarins <b>12</b> with 1-silyloxydienes <b>10</b> to give the adducts <b>13</b> which are then converted into <b>14</b> in one step via treatment with base and loss of the cyano and silyloxy groups.