Macrocycles via Tsuji-Trost Allylation

This particular transformation cleverly exploits the polyfunctional character of the reacting units. It starts with an oxidative insertion of Pd° into the allylic moiety leading to the formation of a dipolar r-allylpalladium species. This step usually occurs with particular ease since the strain of the epoxide ring is released. The resulting alkoxide adjacent to the TT-allyl unit acts as a base and deprotonates the pre-nucleophile (/the substrate adopts a suitable conformation. Charge attraction then keeps the emerging nucleophile in the proximity of the electrophilic r-allylpalladium entity, thereby greatly enhances the 

Although the few examples compiled in this review provide by no means a comprehensive picture, their analysis highlights a few general notions concerning templated ring closure reactions. They show beyond doubt that a template effect is not a uniform phenomenon and no simplistic global picture can be drawn. The effect may be thermody- 

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