Synthesis of 3, 6-dihydro-2H-pyran-2-ones via cationic palladium (II) complex-catalyzed tandem [2+ 2] cycloaddition-allylic rearrangement of ketene with α, β- …
Treatment of ketene with α, β-unsaturated aldehydes and ketones in the presence of [Pd (dppb)(PhCN) 2](BF4) 2 leads to the formation of 4-vinyloxetan-2-ones, which rearrange under the conditions to give 3, 6-dihydro-2H-pyran-2-ones in a variety of yields, depending on the substituents. Asymmetric induction with up to 57% de has been achieved by using α, β-unsaturated aldehydes bearing an asymmetric carbon center at the β-position. A ...
