Abstract
Diketene-acetone adduct (1) generates acetylketene (2) under heating. In order to compare the reactivity of 2 with that of diketene, the reaction of 1 with electron-rich olefins was investigated. On heating with 1, primary enamines (3a-d) produced the corresponding 3-substituted 2, 6-dimethyl-4 (1H)-pyridones (4a-d), while the tertiary enamine 3e gave the 4-pyrone derivative (7). The reaction of 1 with ketene acetals (8) gave the 2, 2-diethoxy-2, 3-dihydro-4-pyrone derivatives (9). The vinyl ether derivatives 13 similarly reacted with 1 to give the 4-pyrone derivative 15 or 16 as the major product. The result shows that both diketene and 2 react with electron-rich olefins in a similar manner.
