Synthesis of Spiro[imidazole‐4,3′‐pyrrolo[1,2‐a]quinolin]‐ 5‐ones via 1,3‐Dipolar Cycloaddition of Quinolinium Ylides with Arylydeneimidazol‐4‐ones

Design of spirocyclic scaffolds, which are able for direct interaction with biological targets, is a developing trend in medicinal chemistry. In continuation of the previous work on HIV‐1 inhibitors, a synthetic approach towards spiro[imidazole‐4,3′‐pyrrolo[1,2‐a]quinolin]‐5‐ones via 1,3‐dipolar cycloaddition of quinolinium ylides with arylydeneimidazol‐4‐ones was outlined. Derivatives with various substitution pattern were prepared in 42–86 % yields. Use of 2,2,2‐trifluoroethanol as a solvent is crucial for successful preparation of the derivatives, its role is sought as prolonging lifetime of the cycloadducts.