One‐pot Synthesis and Antitubercular Activity of Imidazo[2,1‐b]thiazol‐1H‐pyrazolylphosphonates

Abstract

Herein, we present an effective one‐pot method for the synthesis of imidazo[2,1‐b]thiazole‐pyrazole phosphonates from 5‐imidazo[2,1‐b] thiazole carboxaldehydes. The reaction involves a 1,3‐dipolar cycloaddition between in situ generated α,β‐unsaturated ketones and the Bestmann–Ohira reagent (BOR), facilitated by a base, leading to the formation of pyrazole phosphonates as the sole regioisomer with excellent yields. The in vitro evaluation of the newly synthesized compounds 4(a–x) against Mycobacterium tuberculosis H37Rv (Mtb) identified compound 4 o as the most effective analogue (MIC: 6.25 μg/mL; 10.40 μM).