The challenge of correct choice of chiral ligands to achieve high enantioselectivity is typically met through high throughput screening or simply trial-and-error approaches experimentally,which can be costly in terms of personnel and time.Computational method is able to screen a large library of ligands quickly and without the need to purchase or synthesis the ligands ahead of time.In stereoselective reactions,the selectivity determining species is typically a transition state.Reaction specific force field can be utilized to describe and get the relative energies of the diastereomeric transition states.Thus it can be used for selectivity prediction.QM guided molecular mechanics(Q2MM)method,which derives MM parameters from QM data,is an automatic transition state force field development strategy1(Sheme 1).