Synthesis of Bis-(2-mercaptoimidazole)-4,4-butylidene

Ethyl butylidene-bis-3-phthalimidoacetoacetate (II) was prepared by condensation of ethyl-3-phthalimido-acetoacetate and n-butyraldehyde in the presence of piperidine in benzene. Compound II was hydrolysed by hydrochloric acid followed by cyclization with potassium thiocyanate to yield bis(2-mercaptoimidazole)-4,4-butylidene (IV).