Cascade carbopalladation hydride termination

Cascade carbopalladation sequences after attack on an alkene are most commonly terminated by dehydropallada-tion, if a / -hydride is available in a yy//-orientation. The intramolecular carbopalladation starting from the monocyclic diene 122 with a geminally disubstituted alkene terminator leads to a neopentylpalladium intermediate 123, which cannot undergo /J-dehydropalladation, but continue the cascade by a carbopalladation to eventually form the... 

Cascade carbopalladation sequences after attack on an alkene are most commonly terminated by dehydropalladation, if a /S-hydride is present in a yn-orientation (see above). 

Norbomene can serve as an excellent external relay, for example, for the alkenylpalla-dium species first formed by intramolecular carbopalladation of an ort/to-alkynyl-substituted arylpalladium halide. The 2-alkenylnorbonylpalladium halide formed by intermolecular carbopalladation then undergoes another intramolecular carbopalladation, this one in a 3-exo-trig mode, and subsequent /3-hydride elimination terminates the cascade process to yield a cyclopropanated norbomene derivative (Scheme... 

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