Search for "spirocyclopentaneoxindoles" in Full Text gives 2 result(s) in Beilstein Journal of Organic Chemistry.
Beilstein J. Org. Chem. 2017, 13, 1342–1349, doi:10.3762/bjoc.13.131
Beilstein J. Org. Chem. 2012, 8, 1098–1104, doi:10.3762/bjoc.8.121