Synthesis and synergistic, additive inhibitory effects of novel spiro derivatives against ringworm infections.

An environmentally benign solvent free synthesis of various spiro-1,4-dihydropyridines (1,4-DHPs) incorporating 2-oxindole/piperidines is performed in 5-8 min with reasonable purity in 80-90% yield under microwave irradiation using montmorillonite KSF as an inorganic solid support. The reaction is found to be general with respect to various cyclic carbonyl compounds, e.g. cyclohexanone, substituted indole-2,3-dione, and piperidinone derivatives. In our study, these compounds were also found effective against dermatophytes and other fungal organisms. Our results suggest that novel spiro derivatives can be used for the treatment of dermatophytosis or ringworm infections.