Complexation of AgNTf2 with 1a makes silicon atom of TIPS group susceptible to SN2 nucleophilic attack by carbamate 2a. The barrier of this process (TS1) is only 18.3 kcal/mol (figure ). Unlike common SN2 reaction in organic chemistry, this process leads to five coordinated silicon complex INT1, which then dissociate into silver-ketene INT2a and TIPS + coordinated carbamate INT2b. The relatively large size and the d-orbital of silicon atom contributed the SN2 process . The strong interaction between Ag+ and π-bond make silver-ketene INT2a a very good leaving group which also promoted this process .