B. Christenson, T. Olsson, C. Ullenius
1989
Citations
0
Influential Citations
33
Citations
Journal
Tetrahedron
Abstract
Abstract 1H and 13C NMR spectra of solutions obtained by mixing Me2CuLi, 1, or Ph2CuLi, 2, with methyl 3-[2-(1-methoxyethyl)phenyl]propenoate, 3, labelled in C2 (99% 13C), 3∗, methyl 3-(2-methoxymethylphenyl)propenoate, 4, methyl (S)-3-[2-(1-dimethylaminoethyl)phenyl]propenoate, 5, and methyl 3-(2-dimethylaminomethylphenyl)-propenoate, 6, in CD2CI2/THF in the temperature range −90°–+20°C have shown the formation of more than one copper-alkene π-complex from each enoate. The 13C labelled enoate 3∗ on addition to 1 forms at least four isomeric π-complexes as proved by the presence of four C2 signals around 52 ppm in the 13C NMR spectrum. Two dynamic processes have been observed, interconversion of different π-complexes and the reversible formation of the π-complexes, that lead to equilibrium mixtures of the copper-enoate species before carbon-carbon bond formation.