THEORETICAL EVIDENCE FOR STEREOSELECTIVE LITHIATIONS OF 2-ALKOXY-1,1-DIIODO-1-ALKENES - AN AB-INITIO STUDY

Ab initio calculations with complete geometry optimization are reporte d for monomeric Z- and E-2-methoxy-1-iodo-1-lithio-2-phenyl-1-alkenes. All the stationary points are true local minima on the energy surface s. The structural data of the lithioalkenes show clear-cut evidence fo r the Li-Phenyl interaction in Z-isomer and the Li-O chelation in E-is omer in gas-phase, Based on the ab initio energies, Li-Phenyl interact ion should be less relevant than Li,O chelation. Both effects are abse nt when coordination by solvent (water) is accounted. Inclusion of sol vation by solvent continuum model (IPCM) seems essential to rationaliz e the experimental results. (C) 1997 Elsevier Science S.A.