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.