Organolithium reagents effect a regioselective SN2 nucleophilic cleavage of α,β-ethylenic epoxides only when BF3·Et2O is added. The reaction works with a variety of RLi reagents and with cyclic as well as acyclic epoxides.
The use of trialkylorganozincates and tetraalkylaluminates allows regioselective SN2 nucleophilic opening of vinylic epoxides. The reaction occurs with an anti-substitution pattern and can be applied to a wide range of substrates. We also show that the solvent and the structure of the epoxide have an influence on the substitution products ratio.