Method for producing thiazolidinediones, and new thiazolidinediones

Improved process of compounds of formula III in which A denotes CH=CH or S W denotes O X denotes S, O or NR2 in which the residue R2 is hydrogen or C1-C6 alkyl, Y denotes CH or N R denotes naphthyl, thienyl or phenyl which is optionally monosubstituted or disubstituted with C1-C3 alkyl, CF3, C1-C3 alkoxy, F, Cl or bromine, R1 denotes hydrogen or C1-C6 alkyl and n denotes 1-3 by reducing a compound of the general formula IV, ,2 in which A, W, X, Y, R, R1 and n have the meanings stated above with activated aluminium in a protic solvent, as well as new compounds of formula III and pharmaceutical preparations containing these compounds.