Aldehydes synthesis from triazolines

The possible general mechanism for the enolate-mediated synthesis of 1,2,3-triazoles from active methylene compounds, enolizable aldehydes 69, enolizable ketones 71, and substituted acetonitriles 73 is illustrated in Scheme 4.26. First, the reaction of the catalyst (base) with the CH acid 76 generated the enolate A, which on in situ treatment with Ar-Ng 2 selectively furnished the adduct 1,2,3-triazolines B through a concerted [3-1-2]-cycloaddition or stepwise amination-cyclization reaction. Adduct B further transformed into the 1,2,3-triazole 77 through the rapid elimination of water under ambient conditions induced by the basic nature of the catalyst. 

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