**2.3 Aza benzoin reaction**

The coupling of Breslow intermediate to imines was reported by Murry et al. for the first time [18]. NHC addition to highly electrophilic N-BOC imines leads to the formation of corresponding aza-Breslow intermediate, but this can be reversible under suitable reaction condition to obtain a pure 2-amino ketone [19]. Enders et al., reported the first aza benzoin reaction with trifluoromethyl ketimines using achiral thiazonium precatalyst [20]. Where enals reacts with trifluoromethyl ketone, obtained excellent enantioselectivity using chiral triazolium catalyst, which also furnishes electronic diminished groups tolerance (**Figure 7**) [21].
