Palladium-Catalyzed Seven-Membered Silacycle Construction: 1,7-Enyne Hydroxycyclization To Give a Benzosilepine Skeleton.

A palladium-catalyzed hydroxycyclization reaction of 1,7-enynes to afford seven-membered silacycles (1 H-benzo[ b]silepine skeletons) is developed. This is the first example of both seven-membered ring construction from enynes using a palladium catalyst and hydroxycyclization of enynes to give seven-membered silacycles.

Ruthenium-Catalyzed 1,6-Aromatic Enamide-Silylalkyne Cycloisomerization: Approach to 2,3-Disubstituted Indoles.

Cycloisomerization is an atom economic procedure that converts dienes and enynes into cyclic molecules. To date, cycloisomerization between enamides and silylalkynes has not been explored. We found that N-acyl-N-vinyl-2-silylalkynylaniline derivatives undergo a cycloisomerization in the presence of a well-defined ruthenium hydride to give a 2,3-disubstitued indole. The vinyl and silylmethyl substituents on the 2- and 3-positions of the indole can be easily converted to other functional groups.

Cycloisomerization between Aryl Enol Ether and Silylalkynes under Ruthenium Hydride Catalysis: Synthesis of 2,3-Disubstituted Benzofurans.

Metal-catalyzed cycloisomerization reactions of 1,n-enynes have become conceptually and chemically attractive processes in the search for atom economy, which is a key subject of current research. However, metal-catalyzed cycloisomerization between aryl enol ether and silylalkynes has not been developed. The ruthenium hydride complex catalyzed cycloisomerization between aryl enol ether and silylalkynes is reported to give benzofurans having useful functional groups, vinyl and trimethylsilylmethyl, on the 2- and 3-positions, respectively.