Process for production of 4-substituted 1, 2-diphenyl-3,5-dioxopyrazolidines

Abstract From the Canadian patent

This invention is concerned with a novel process for production of 4-substituted 1,2-diphenyl-3,5-dioxopyrazolidines of general formula I, where R and R1, which by be identical to or different from each other represent a hydrogen atom, a lower alkyl group a phenyl group or the group, -COOR" (where R" means hydrogen or a lower alkyl group) and A a hydrogen atom or a hydroxyl group. Compounds of general formula I exist in the so-called Z- and in the isomeric E-form, which fall both under the general formula designated above (as well as mixtures thereof). The compounds of formula I are prepared by either (a) reacting a cyclosemiacetal of general formula II, where A' represents hydrogen or an …