Aza-benzoin condensation

Under presented conditions (triazolium bromide XI and DBU in CHjCy, the reaction proceeds by a cascade reaction (i) first, amidation (aza-benzoin condensation between enal and nitrosoarene, as outlined in Scheme 5.33) produces A-hydroxyacrylamide 51, and (ii) second, in the presence of base such as DBU or triazole carbene [41], oxo-Michael addition of 51 to enones would afford products 52 (Scheme 5.35). 

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