Аннотация:
Multicomponent condensations of alkyl(thio)ureas, formaldehyde and (thio)barbituric acids afford new spiro heterocyclic compounds, viz., 8- and 8,10-substituted 2,4,8,10-tetraazaspiro[5.5]undecane-1,3,5,9-tetraones (barbiturils) and their thio analogues.