Early, it was found that benzoin condensed with ethyl cyanoacetate in the presence of ethoxide ion to give 3- cyano-3,4-diphenyl-2(5H)-
furanone 1. On reinvestigating this reaction, we were able to isolate 1 together with another product, in low yield, which was proved to be
3-cyano-3,4-diphenyl-2(3H)-furanone 2. The latter is formed by isomerization of 1 under the basic conditions employed. Energy
calculations revealed that the 2(5H)-furanone 1 is more stable than the 2(3H)-isomer by 24.5 KJ/mole. The behavior of the two furanones 1
and 2 towards some nitrogen nucleophiles viz. hydrazine hydrate, benzylamine and ammonium acetate is studied. The unfavored 1,4
addition of these nucleophiles to the α,β-unsaturated carbonyl moiety of 1 is explained in terms of steric and electronic effects of the phenyl
group at position 4 .The nitrile groups at position 3 of the furanones 1 and 2 were utilized to construct thiazolidine and tetrazole rings by
the action of thioglycollic acid and sodium azide respectively. The structures of all the products obtained were illustrated from their
analytical and spectral properties.
Key words: 2(5H)-furanone, 2(3H)-furanone, nitrogen, nucleophiles, unfavored 1,4- addition , thiazolidine and tetrazole rings..