| 摘要 |
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 etherified hydroxyl group, preferably the .beta.-methoxyethoxymethoxy (=MEM) group, with a triarylphosphorane derivative of general formula III where R and R' have the above-mentioned meanings and Ar represents a phenyl group (optionally substituted with an inert group such as methyl, methoxy or phenyl) and, subsequently, optionally liberating the etherified hydroxy group by means of a mild Lewis-acid; or reacting the aldehyde of the formula IIa with a compound of formula III as defined above. The compounds of formula I are valuable antiphologistically active compounds. The intermediates of formulae II and IIa are novel and form part of this invention. They are prepared by rearrangement or deketalisation of the corresponding cyclic acetals of general formula IV where A' has the meanings indicated above. This rearrangement may be effected, for example, by means of simple heating in aqueous ethanol. |
