- A hydride transfer reaction from salts of carbanions to activated olefins
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A novel reaction - a β-elimination of a hydride ion from carbanion salts RM (R = Li, MgBr) and R2N-Li+, and its transfer to tetra-substituted activated olefins of the type Ar2C=C(CN)CO2R (R = Me,Et), was studied. Yields of the reduced H--acceptor were used to follow the extent of the H--transfer reaction. A competing Michael addition reaction of RM to the activated olefin also took place. The effects of the solvation properties of the solvent, the reaction temperature, the positive counter-ion, and of various structural features of the H--donor and the H--acceptor, were studied. The structural factors associated with both reactants, played a critically significant role due to the bimolecularity of the reaction. A benzyl substituent at C(β) of RM, a methine-type β-carbon, or a small size of R of RM, resulted in a relatively high extent of the H--transfer reaction. It is suggested that the presently studied β-elimination of a hydride ion takes place by a bimolecular E2cB-type mechanism.
- Feit, Ben-Ami,Shapira, Sarit,Herbst, Amatzya
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p. 317 - 328
(2007/10/02)
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