4- Ethynylquinoline complexes

For the formation of the 4-ethynylquinoline complexes a mechanism was proposed involving nucleophilic attack of the terminal carbon of the butatrienylidene ligand at the imine carbon, followed by C—C bond formation between the ortho carbon of the N-aryl group and C3 of the butatrienylidene ligand. Deprotonation finally affords 4-ethynylquinoline complexes (Scheme 3.27). Some preference was observed for quinoline formation with the more electron-rich metal centers, whereas... 

Scheme 3.27 Formation of ethynylquinoline complexes in the reaction of butatrienylidene complexes with imines.

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