An exo-diene moiety of various ortho-quinodimethanes, regardless of its transient character, was inserted into a Sn-Sn sigma-bond of hexabutyldistannane in the presence of a palladium catalyst, giving alpha,alpha'-bis(tributylstannyl)-o-xylenes straightforwardly.
Intramolecular S<sub>N</sub>′-Type Aromatic Substitution of Benzylic Carbonates at their Para-Position
es. In the catalytic cyclization, the internal nucleophile attacks not the ortho-carbon but the para-carbon of the benzylic ester. The [3 + 2] cycloaddition of m-(silylmethyl)benzyl carbonates with alkylidene malonates was developed from the palladium-catalyzedintramolecular SN′-type aromatic substitution.
This invention relates to silylated aromatic fluoroketones possessing acetylcholinesterase-inhibiting properties and to their use in the treatment of Alzheimer disease and senile dementia.