Some fused heterocyclic oxazoles and imidazols rings were synthesized from reaction of N-acetyl cysteine with different treatment.After thiol group protection, N-acetyl-S-ethyl cysteine (2) had been esterified to give ester 3 which cyclized to oxazole 4 with phosphorus oxychloride.N-acetyl-S-ethyl cysteine 2 were converted to acid chloride 5 with thionyle chloride.Amide 6 were synthesized from 5 w...