Download full text in PDF Opens in a new window. Article suggestions will be shown in a dialog on return to ScienceDirect. ... Please enable JavaScript to use all the features on this page. ... Grinding of isatins with malononitrile in the presence of 1–5 equiv. of water for 15 min at room temperature affords the corresponding (2-oxo-1,2-dihydro-3H-indol-3-ylidene)malononitriles , the Knoevenagel condensation products, in 89–99% yields.