Base-Promoted Expedient Access to Spiroisatins: Synthesis and Antitubercular Evaluation of 1H‑1,2,3-Triazole-Tethered Spiroisatin–Ferrocene and Isatin–Ferrocene Conjugates

The use of sodium hydride provides a convenient access to the synthesis of C-5-functionalized spiroisatins with the absence of the typical drawbacks associated with conventional protocols. The synthesized precursors, viz. N-alkylazido spiroisatins and their unprotected counterparts, were explored in Cu-mediated azide–alkyne cycloaddition reactions to probe the antitubercular structure–activity relationships (SAR) within the isatin–ferrocene–triazole conjugate family. The antitubercular evaluation studies of the synthesized conjugates revealed an improvement in the minimal inhibitory concentration (MIC) with the introduction of ferrocene nucleus, as evidenced by spiroisatin–ferrocene and isatin–ferrocene hybrids.