Nucleophilic reactions of various enol silylethers with carbocation species generated from propargylsilylethers by the action of a Lewis acid have been developed. The present method is highly useful for the introduction of allenic or enyne functionalities into the alpha-position of substituted ketones. [reaction--see text]
A new catalytic asymmetric tandem α‐alkenyl addition/proton shift reaction of silyl enol ethers with ketimines was serendipitously discovered in the presence of chiral N,N′‐dioxide/ZnII complexes. The proton shift preferentially proceeded instead of a silyl shift after α‐alkenyl addition of silyl enol ether to the ketimine. A wide range of β‐amino silyl enol ethers were synthesized in high yields with
A highly efficient asymmetric imino-ene reaction of cyclic ketimines with silylenolethers was developed. Various chiral benzosultam derivatives were obtained in excellent yields (up to 99%), enantioselectivities (up to 99% ee), and diastereoselectivities (up to >19:1 dr) by utilizing a Ni(BF4)2·6H2O/N,N'-dioxide complex as the catalyst. A possible transition state model was proposed to explain the