Our calculation is excellent in accordance with experimental observations. Kozmin et al. claimed that the ynamides and simple internal alkynes are unreactive in the same conditions. This is a strong support of our proposed SMH mechanism, which highlight the importance of the silylium ion Migration. Ynamides is electron richer than siloxy-alkyne, if this reaction take place through the author proposed NUA mechanism, the ynamides should be more reactive. Furthermore, using deuterated amide 2a, no primary deuterium isotope effect (kH/kD=1.03) was observed, which means that hydrogen migration is not the rate determine step. Our calculations shows that silylium ion migration (TS1) is the rate determine step in this reaction, if we reduce the size of silyl group, the reaction rate may be accelerated.