Formation of Neopentylpalladium and its Termination by Anion Capture

Some examples of termination by anion capture are as follows. Reactions are terminated by carbonylation. Domino carbopalladation and carbonylation of the iododiene 163 under 1 atm of CO via a neopentylpalladium intermediate gave the cyclized ester 164 with high yield and diastereoselectivity [82], The iodide 165 underwent 5-exo cyclization to generate the neopentylpalladium 166 and its carbonylation gave the acylpalladium 167. Intramolecular attack by malonate anion affords 168 [83]. 

Total synthesis of capnellene has been achieved by X-cyclization of the cyclo-pentene 169. The tricyclic compounds 170 and 171 were prepared by the attack of malonate anion using TFP as a ligand, and capnellene was synthesized from 170 [84]. 

Termination occurs by transmetallation with organometallic compounds of B and Sn, followed by reductive elimination. The aryl iodide 172 underwent 5-exo cyclization. Transmetallation of the alkylpalladium with vinyltin reagent, followed by reductive elimination, afforded 173 [85]. The anion trap is not limited to the 

Hydroarylation of olehns by attack of hydride derived from formic acid is frequently used. Cyclization of 179 generates the neopentylpalladium 180, which is trapped with the hydride to yield the hydroarylation product 181 [88]. 

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