Synthesis of Bis(indolyl)methanes via thiourea organocatalysts carrying 3,5-bis(trifluoromethyl)phenyl or 3,5-dichlorophenyl moieties

Abstract

Bis(indolyl)methane derivatives (BIMs) were synthesized in moderate to good yields by electrophilic aromatic substitution of indole (27) with various aldehydes or imines in the presence of thiourea organocatalysts carrying 3,5-bis(trifluoromethyl)phenyl or 3,5-dichlorophenyl moieties. Reactions were performed under conventional and microwave (MW) irradiation without solvent. The most active organocatalyst for aldehydes was thiourea 3 and for imines, the thiourea 6. For compound 11 derived from 2,4,6-trimethoxybenzaldehyde (30) its structure was confirmed by X-ray analysis. Furthermore, some of the synthesized compounds were evaluated for their effectiveness as antibacterials. Compounds 3, 9, 10 and 13 showed inhibitory activity against Gram positive bacteria whereas compound 5 showed inhibitory activity against Gram positive and Gram negative bacteria.