Metala ester

Apparent Insertions Sometimes a reaction that is an apparent insertion can go by an entirely different route. A good example is shown in Eq. 7.14. The late metal alkoxide is unstable (since MeO is a good tt donor) and the MeO group dissociates as MeO to leave a 2e site at the cationic metal. The CO present then binds to this 2e site, and is strongly activated toward nucleophilic attack at the CO carbon by the positive charge on the metal. The product is the interesting metala-ester complex shown in Eq. 7.14 ... 

The nucleophilic attack of methanol instead of water can give a metala-ester, L (COOR), which is stable because it has no p-H. 

Chamoin, S. Houldsworth, S. Snieckus, V. The Stille Cross Coupling Reactions on Solid Support. Link to Solution Phase Directed ortho Metala-tion. An Ester Linker Approach to Styryl, Biaryl and Heterobiaryl Carboxylic Acids, Tetrahedron Lett. 1998, 39, 4175-4178. 

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