4-Acyloxy-2,5-diphenyl-3-oxo-2,3-dihydrothiophene 1,1-dioxides as acylating agents in the Friedel-Crafts reaction

The 'activated esters', 4-acyloxy-2,5-diphenyl-3-oxo-2,3-dihydrothiophene 1,1-dioxides, easily accessible from 4,6-diphenylthieno[3,4-d][1,3]dioxol-2-one 5,5-dioxide, have been found to be excellent acylating agents in the Friedel-Crafts reaction with olefins and activated aromatic compounds. In the case of the olefins, product mixtures containing β-chloroketones were treated with 1,8-diazabicyclo[5.4.0]undex-7-ene to afford the corresponding unsaturated ketones in 30 - 73% yields, whereas aromatic ketones were obtained in high yields. The activated esters react slightly faster than the corresponding alkanoyl chlorides, and form fewer by-products