Figure 8: Proposed pre-catalytic cycle (dormant period).

The reactive Lewis acid organocatalyst (1-TMS) is formed in the presence of TMSCN (3) or silyl ketene acetal (7a) and quenched in the presence of H2O or silanol 9.
The reactive Lewis acid organocatalyst (1-TMS) is formed in the presence of TMSCN (3) or silyl ketene acetal (7a) and quenched in the presence of H2O or silanol 9.