Abstract
Reduction of carbonyl compounds with metallic hydrides is the basisprocess of organic synthesis. It is a very interesting reaction as the reaction mechanism depends on the series of metallic hydrides.For the nucleophilic addition reaction with aromatic aldehyde and ketone, two possible reaction mechanisms are suggested, the polar addition(PL) mechanism and single electron transfer(SET)-radical coupling(RC) sequence.Previously we have carried out the ab initio molecular orbital study for the PL mechanism of BH3, BMe2H6, B2H6,AlH3,AlMe2H6.In the present study, we have investigated the SET mechanism of the reduction of MeMgCl and MeLi with benzaldehyde. The geometries of all of the stationary points have been fully optimized at the RHF and B3LYP levels of theory using the 3-21G(d),6-31G(d) basis set. Thesegeometries were then refined by using MP2 and the 6-311(d) basis set. For the excited state (SET state), CIS method was used. First, we have confirmed on the reaction of formaldehyde withMeMgCl, the reaction proceeds via the two steps as suggested by experiments, and the former is the rate-determining step.Furthermore, we have found that this tendency is emphasized by solvent effect.
