Palladium-Catalyzed Annulation of Internal Alkynes by Arene-Containing Vinylic Iodides and Triflates
摘要:
In the presence of a palladium catalyst, internal alkynes undergo carboannulation by cyclic and acyclic vinylic iodides and triflates bearing a neighboring aromatic ring to produce a variety of carbocycles. For example, a number of 9,10-disubstituted-1,2,3,4-tetrahydrophenanthrenes have been prepared in good yields through the palladium-catalyzed annulation of internal alkynes by 2-phenyl-1-cyclohexenyl triflate (1) or 1-iodo-2-phenylcyclohexene (2). This annulation process is fairly general and highly regioselective. The process appears to involve oxidative addition of the vinylic substrate to Pd(0) to produce a vinylic palladium intermediate, which adds the carbon moiety to the less hindered end and the palladium to the more hindered end of the alkyne, followed by intramolecular ring closure onto the neighboring aryl group. The scope and limitations of this methodology are discussed.
Palladium-catalysed hydroarylation and hydrovinylation of 3,3-dialkoxy-1-aryl-1-propynes. An approach to 3-aryl- and 3-vinylquinolines
作者:Sandro Cacchi、Giancarlo Fabrizi、Fabio Marinelli、Leonardo Moro、Paola Pace
DOI:10.1016/0040-4020(96)00557-1
日期:1996.7
Acetylenic acetals and ketals have been reacted with aryl and vinyl halides to generate hydroarylation and hydrovinylation products. The reaction proceeds with high regioselectivity. The carbopalladation step appears to be mainly controlled by stericeffects and the new carbon-carbon bond is generated preferentially on the carbon bearing the acetal group. The reaction has been employed to develop a