Stereoselective addition of R2CuLi to ortho-substituted methyl cinnamates intramolecular assistance and solvent effects
1991; Elsevier BV; Volume: 47; Issue: 26 Linguagem: Inglês
10.1016/s0040-4020(01)86478-4
ISSN1464-5416
AutoresBeritte Christenson, Gerd Hallnemo, Christina Ullenius,
Tópico(s)Cyclopropane Reaction Mechanisms
ResumoHigh chemical yields are obtained on the addition of the ortho-substituted enoates 1, 2, 3, and 4 to Me 2 CuLi or Ph 2 CuLi in non-coordinating solvents, CH 2 Cl 2 or toluene. The results underline the strong effect of solvent on reactions between organocuprates and enoates as the corresponding reactions in diethyl ether afforded low yields and moderate stereoselectivity. No reaction was observed when THF was used. The high stereoseleclivity observed with the dimethylaminoethyl substituted enoate 4 in non-coordinating solvents can be accommodated by a mechanistic model for the reaction based on chelation control, within a copper-alkene π-complex.
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