THERMAL ADDITION-REACTION OF AROYLKETENES WITH CYCLIC ENOL ETHERS

Thermal reaction of aroylketenes 2 with cyclic enol ethers such as 2,3 -dihydrofuran (A), 2,3-dihydropyran (B), 1-trimethylsiloxycylopentene (C), 1-trimethylsilyloxyclohexene (D), 3-trimethylsilyloxyindene (E), and 4-trimethylsilyoxy-1,2-dihydronaphalene (F) was carried out to inv estigate the reactivity of 2 with these olefins, The main reaction was Michael-type addition to give the 1,3-diketones 3 and 9, and the 1,3, 5-triketones 13, 15, 18, and 20, depending on the olefins used, The ad dition of the olefins nas facilitated by introduction of a nitro or ch loro group Into the arg 1 part of 2 and was profoundly retarded by ste ric hindrance of the olefins.