C-H functionalization of alkyl 1,2,3-triazole-4-carboxylates using an in situ generated Turbo-Hauser base

An efficient method for the C-H functionalization of N-protected alkyl 1,2,3-triazole-4-carboxylates with various C-, P- and S-electrophiles using an in situ generated Turbo-Hauser base has been developed. The resulting compounds underwent N- and O-deprotection to afford the corresponding NH-5-substituted 1,2,3-triazole-4-carboxylates, which possess multiple sites for further functionalization. The preferred tautomeric forms and pKa values of several representative compounds are discussed.