O‐Glycosylation/Alkylation and Antimicrobial Activity of 4,6‐Diaryl‐2‐Oxonicotinonitrile Derivatives

A series of glycosylation and alkylation reactions of 6‐phenanthernyl‐2‐pyridone derivatives 1a, 1b containing electron withdrawing and electron donating substituents at 4‐position is reported. Regioselective 2‐O‐alkylated/glycosylated products were obtained exclusively, irrespective of the electronic nature of alkylating or the glycosyling agent. Glycosylation of 1a, 1b with glucosyl/galactosyl and lactosyl bromides afforded 2a, 2b; 4a, 4b; and 6a, respectively. Alkylation of 1a, 1b with epichlorohydrin, propargyl, allyl bromides, and 3‐chloropropanol resulted in compounds 8, 9, 10 and 13, respectively. Deprotection of O‐glycosylated products under conventional conditions provided the free glycosides 3a, 3b; 5a, 5b; 7a,12; and 13, respectively. The minimal inhibitory concentration for some of the newly synthesized compounds showed high significant activity against Gram (+ve) and Gram (−ve) and antifungal activities. Among the screened compounds, the 4‐trifluromethyl phenyl derivatives 2a, 3a, 4a, 8a, and 11a exhibited strong antimicrobial activity.