3 6 7 dichloro 2 cyclopentylmethyl 2 3 dihydro 2 methyl 1 oxo 1h inden 5 yl 4 hydroxy 1h pyrrole 2 5 dione as a foam which was then dried under high vacuum at 90 u00b0 c for 2 hours to give 3 6 g 63 calculated for c 20 h 10 cl 2 no 4 the preparation is carried out essentially as described in example 1 steps a through d except that an equimolar amount of 2 allyl 6 7 dichloro 2 3 dihydro 5 hydroxy 2 methyl 1h inden 1 one is substituted for the 6 7 dichloro 2 cyclopentyl 2 3 dihydro 5 hydroxy 2 methyl 1h inden 1 one used in example 1 step a then the product of steps a b and c are used in each subsequent step so that 3 2 allyl 6 7 dichloro 2 3 dihydro 2 methyl 1 oxo 1h inden 5 yl 4 hydroxy 1h pyrrole 2 5 dione and its 1 methylpiperazine salt is obtained in step d the preparation is conducted essentially as described in example 5 step b except that an equimolar amount of 6 7 dichloro 2 3 dihydro 1 oxo 2 phenyl 2 propargyl 1h inden 5 yl oxy acetic acid is used in place of the 6 7 dichloro 2 cyclopentylmethyl 2 3 dihydro 5 methoxy 2 methyl 1h inden 1 one used in example 5 step b there is thus obtained 6 7 dichloro 2 3 dihydro.