The first example of exploiting the trifunctional character of alkyl 4-chloro-2-diazo-3-oxobutanoates
in the reactions with vicinal N,S-bis-nucleophiles leading to the formation of bicyclic 6,7-dihydro-4H-[1,2,3]triazolo[5,1-c][1,4]thiazines is presented. The key to the successful realization of the atom-economical
synthetic strategy is the initial S
N
2 event, which facilitates the subsequent domino 1,2,3-triazole formation via the
Wolff reaction. Equally important is the choice of sodium acetate as the base: acetic
acid formed in the course of the initial nucleophilic substitution acts as an efficient
catalyst for the Wolff reaction, which suppresses the competing, unwanted fragmentation
path (observed when other bases are used).
Key words
diazo transfer - multicenter reactions - nucleophilic substitution - domino reactions
- Wolff 1,2,3-triazole synthesis
