Synthesis of potential fungicidal bibenzyls from bio-renewable source

Acetylation of bibenzyl 1 yields 4,4'-diacetylbibenzyl 2, which on condensation with different aryl amines gives corresponding Schiff's bases in situ. Nucleophilic addition of 2-mercaptopropionic acid or 2-mercaptosuccinic acid on Schiff's bases followed by cyclodehydration in solvent-free condition under microwave irradiation affords 4,4-bis(3"-aryl-2"-methyl-5"-methyl/carboxymethyl-4"-oxo-thiazolidin-2"-yl)bibenzyl 3a-n with excellent yield (88-94%). The rate of the reaction is enhanced 225 times in comparison with conventional method. Antifungal screening results on Fusarium oxysporum and Penicillium citrinum show that most of the synthesized compounds display promising antifungal activity, comparable with Griseofulvin and Dithane M-45 as standards.