A strategic approach for synthesis of benzimidazo[2,1-b]thiazolidinone appended dispirooxindole hybrids via [3+2] cycloaddition using fluoro-ethanol as solvent

A series of new functionalized analogues of spirooxindole-pyrrolidines have been synthesized by com-prising benzimidazo[2,1-b]thiazolidinone heterocyclic fused moiety via 1,3-dipolar cycloaddition reac-tion strategy under an efficient and eco-comfortable reaction conditions. In the present study a new dipolarophiles alkyl(Z)-2-(3-oxobenzo[4,5]imidazo[2,1-b]thiazol-2(3H)-ylidene)acetate reacts efficiently with non-stabilized 1,3-dipolar component azomethine ylide formed in situ from the reaction of substituted isatins and alpha-amino acid sarcosine to affording new complex heterocyclic hybrid i.e.,dispiro[benz-imidazo[2,1-b]thiazole-2,30-pyrrolidine-20,30'-indoline]-40-carboxylates. The present benzimidazo[2,1-b] thiazolidinone grafted dispirooxindole core system formed by the creation of two new C-C and one C-N bonds with multiple stereo centers in one-step operation and reaction proceed with highly regio and exo-selective manner. Further, the present approach is high yielding protocol for synthesis of target cycload-ducts in short reaction time using 2,2,2-trifluoroethanol (TFE) as an efficient reaction medium. The regio-/stereochemistry has been concluded by single crystal X-ray diffraction analysis. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

A series of new functionalized analogues of spirooxindole-pyrrolidines have been synthesized via 1,3-dipolar cycloaddition reaction strategy under efficient and eco-friendly conditions. The reaction formed a complex heterocyclic hybrid with multiple stereo centers in one step, showcasing a high regio- and exo-selective manner. Single crystal X-ray diffraction analysis was used to determine the regio-/stereochemistry.