Alkyne derivatives intermolecular carbopalladation

The inter-intermolecular carbopalladation cascade, starting with the palladium intermediate from /3-halostyrene derivatives and two molecules of an alkyne, does not yield a benzene, but highly substituted fulvene derivatives, albeit in moderate yields only (Scheme 47, Eqs. 1 and Fulvene derivatives are also formed from 1-haloalkenes and 1,6-diynes (Schemed , Eq. 3). ... 

Selective synthesis of benzene derivatives via partially intramolecular cyclic carbopalladation is considerably more complex than the corresponding all-intramolecular processes. As it is generally difficult to specify the cascade-initiation point in the Type Ha cyclization process, it would generally be the least selective path. A priori, the most favorable might be the intra-inter cascade cyclization process (Type lib), since both the point of initiation and the queuing order between the two alkynes is sharply differentiated by the fact that one is intramolecular, while the other is intermolecular. Still, in-... 

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