Oxidative Coupling of 1-(2,6-Dichlorobenzoyl)pyrroles and -pyrazoles and Alkyl Acrylates by Palladium(II) Acetate

Treatments of 1-(2,6-dichlorobenzoyl)-, 3-acetyl-1-(2,6-dichlorobenzoyl)-, 1-(2,6-dichlorobenzoyl)-2-formyl-, and 1-(phenylsulfonyl)pyrroles with palladium acetate and alkyl acrylates gave the corresponding α-alkenyl-substituted pyrroles in good yields, while the reaction of 1-(2,6-dichlorobenzoyl)-2,5-dimethylpyrrole gave small amounts of β-alkenyl-substituted pyrroles. Under similar conditions, 1-(2,6-dichlorobenzoyl)pyrazole and 1-(2,6-dichlorobenzoyl)-3,5-dimethylpyrazole reacted with palladium acetate and alkyl acrylates to give the corresponding 4-alkenyl-substituted pyrazoles. The reaction of 1-(2,6-dichlorobenzoyl)-4-methylpyrazole gave 5-alkenyl-substituted pyrazole