dihydro 5 hydroxy 2 methyl 1h inden 1 one used in example 1 step a and using the product of each step in the subsequent step there are obtained 3 2 butyl 6 7 dichloro 2 cyclopentyl 2 3 dihydro 1 oxo 1h inden 5 yl 4 hydroxy 1h pyrrole 2 5 dione and its 1 methylpiperazine salt analysis for c 22 h 23 cl 2 no 4 calc c 60 55 h 5 31 n 3 23 found c 60 56 h 5 60 n 3 10 the preparation is conducted essentially as described in example 1 steps a through d except that an equimolecular amount of 6 7 dichloro 2 3 dihydro 5 hydroxy 2 methyl 2 1 methylethyl 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 6 7 dichloro 2 3 dihydro 1 oxo methyl 2 1 methylethyl 1h inden 5 yl 4 hydroxy 1h pyrrole 2 5 dione and its 1 methylpiperazine salt are obtained in step d 6 7 dichloro 2 cyclopentylmethyl 2 3 dihydro 5 methoxy 1h inden 1 one 56 7 g 0 181 mole dissolved in dry toluene 200 ml is added dropwise with stirring under nitrogen over 1 hour at room temperature to a suspension of sodium hydride 56 in mineral oil 8 74 g 0 204 mole in toluene 50 ml and dry dimethylformamide 220 ml the mixture is stirred at room temperature for 1 75 hours after completion of.