In　the　presence　of　10　mol%　of　Na2CO3,　the　desired　imidazolidine-spirooxindoles　were　obtained　in　81-99%　yield　with　up　to　99　:　1　dr　by　means　of　the　diastereoselective　[3　+　2]　cycloaddition　of　N-acylhydrazine-derived　imines　with　3-isothiocyanato　oxindoles.　Single-crystal　X-ray　structure　analysis　was　conducted　to　determine　the　relative　stereochemistry　of　the　imidazolidine-spirooxindoles.　Diastereoselective　access　to　the　imidazolidine-spirooxindoles　was　hypothesized　by　the　proposed　mechanism.