“…A crude mixture of 2,5-dihydro-1,3,4thiadiazolidines 2 and 3, which had been obtained from 1 and a solution of diazomethane in Et 2 O, was used for the reactions with tetracyanoethylene and N-phenylmaleimide according to [7]. Crystals of 3', 3',4',4'-tetracyanospiro[pentacyclo[5.4.0.0 2,6 .0 3,10 .0 5,9 ]undecane-8,2'-tetrahydrothiophene] (11) and 7-methylspiro [7-aza-2-thiabicyclo[3.3.0]octane-2,8'-pentacyclo [5.4.0.0 2,6 .0 3,10 .0 5,9 ]undecane-6,8-dione (12) suitable for the crystal-structure determination were grown by slow evaporation of the solvents of solutions in methanol or hexane/CH 2 Cl 2 , respectively, at room temperature. Table 1 and Figs.…”