The spiro-indole derivative, spiro[3H-indole-3,2'-thiazolidine]-2,4'(1
H)-dione, has been synthesized by the reaction of mercaptoacetic acid
with 5-chloroimino-3-(4-fluoro-phenyl)-2H-indol-2-one. The latter comp
ound is prepared in situ from 5-chloroindole-2,3-dione and 4-fluoroani
line. The structure of the title compound confirms the conclusions dra
wn from the spectroscopic studies that the environment of the spiro C
atom is based on tetrahedral geometry having bond angles in the range
109.6 (3)-117.3 (2)-degrees.