Chalcogeno Morita-Baylis-Hillman Reaction of 2-(Methylchalcogeno) phenyl Vinyl Ketones with Aldehydes, Ketones, and α-Dicarbonyl Compounds

摘要

Reactions of 2-(methylchalcogeno) phenyl vinyl ketones 1 and 4 with aldehydes 5 were conducted in the presence of BF_3·Et_2O. The reaction was quenched by addition of Et_3N and gave the Morita-Baylis-Hillman adducts 6-7 in good yields. When the reaction mixture of 1 with 5a was worked up with saturated aqueous NaHCO_3, the sulfonium salt 8a was obtained together with 6. Ketones 10, a-diketones, and a-oxo esters 13, which hardly react in the traditional Morita-Baylis-Hillman reaction, similarly reacted with 2-(methylchalcogeno) phenyl vinyl ketones 1 and 4 to give the Morita-Baylis-Hillman adducts 11-12 and 14-15. Selenochromanones 9 and 16 were obtained together with 7 and 15 from reactions of seleno derivative 4, with 5 and 13 as by-products. The formation mechanism for the sulfonium salt syn-trans-8a is discussed.