Zirconium-catalyzed chemoselective methylalumination of ethers, amines, and sulfides bearing two terminal alkenyl groups

Chemoselectivity in the methylalumination reaction of unsymmetrical ethers, amines, and sulfides bearing two different terminal alkenyl groups, a 13-tetradecenyl group and an allyl, 4-pentenyl or 6-heptenyl group was examined. The methylalumination of the allyl derivatives proceeded with complete chemoselectivity to afford only the 13-tetradecenyl-monomethylated products. In the methylalumination reactions of the 4-pentenyl and the 6-heptenyl derivatives, in addition to the 13-tetradecenyl-monomethylated products, and dimethylated products were also obtained. However, as in the case of the allyl derivatives, monomethylation to the shorter 4-pentenyl or 6-heptenyl group was not observed, except in the case of 6-heptenyl 13-tetradecenyl amine. The unique selectivity was rationalized upon how readily the intramolecular ligand exchange reaction between intermediate zirconocenium–alkene and zirconocenium–heteroatom complexes could occur.

Chemoselectivity in the methylalumination reaction of ethers, amines, and sulfides bearing two different terminal alkenyl groups was examined. The methylalumination of the allyl derivatives proceeded with complete chemoselectivity to afford only the 13-tetradecenyl-monomethylated products. The selectivity was rationalized upon how readily the intramolecular ligand exchange reaction between intermediate zirconocenium–alkene and zirconocenium–heteroatom complexes could occur.Figure optionsDownload as PowerPoint slideHighlights
► Methylalumination of allyl ether, amine, and sulifide chemoselectively proceeded. The selectivity was rationalized upon the intramolecular ligand exchange reaction between intermediate zirconocenium–alkene and zirconocenium–heteroatom complexes.