[4+2] Cycloaddition of o-Xylylenes with Imines Using Palladium Catalyst
摘要:
The cycloaddition of o-(silylmethyl)benzylic carbonates with imines proceeded in the presence of the Pd(eta(3)-C3H5)Cp-DPPPent catalyst, affording the tetrahydroisoquinolines in good to high yields. The reaction rate was remarkably increased by a fluoride additive. In the catalytic cycloaddition, the palladium(0) reacted with the benzylic substrate to form 2-palladaindane, which works as an o-xylylene equivalent. The catalytic reaction is equivalent to the hetero-Diets-Alder reaction of o-xylylene with imines.
[GRAPHICS]A new three-component coupling reaction of methyl 3-trimethylsilylpropiolate, N-tosylimine, and tosylamide mediated by DABCO was developed. This reaction was based on the consecutive alpha- and beta-activation method of propiolate involving intramolecular silyl migration previously developed by our group. On the basis of these results, a new cyclization reaction was designed to find a chrome ne-formin g reaction utilizing salicyl N-tosylimine as a bifunctional substrate.