Synthesis of fluazolate via the application of regioselective [3+2] cyclocondensation and nucleophilic substitution-cyclization strategies

Starting from commercially available 2-chloro-4-fluorobenzoic acid 4, synthesis of fluazolate was achieved in up to 30% overall yield via the key procedure of either regioselective [3+2] cyclocondensation of trifluoromethyl-α,β-ynone 2 with hydrazine hydrate or nucleophilic substitution-cyclization of trifluoromethyl-α,β-dibromoenone 10 with hydrazine hydrate. [Display omitted]