Hydrochloric Acid → 1,9b-dihydro-3-isopropyl-3-methyl-5H-imidazo[2,1-a]isoindole2(3H),5-dione

Participants

Reaction Steps

To a stirred suspension of 10.4 g (0.274 mole) sodium borohydride in 164 ml absolute ethanol under nitrogen was added dropwise at 5° C a solution of 133.9 g (0.548 mole) of 2,5-dihydro-3-isopropyl-3-methyl-3H-imidazo[2,1-a]isoindole-2,5-dione in 155 ml tetrahydrofuran. After the addition, the mixture is stirred a further 3 hours at room temperature and then poured over 1070 g ice with stirring. The mixture is acidified with concentrated HCl and after stirring for 1.5 hours, the precipitate removed by filtration, washed with water and air-dried to give 118.7 g of 1,9b-dihydro-3-isopropyl-3-methyl-5H-imidazo[2,1-a]isoindole-2(3H),5-dione, melting point 178°-200° C.

Provenance & Evidence