7-Phenyl-1 3-diazaspiro[4.4]nonane-2,4-dione

7-Phenyl-1 3-diazaspiro[4.4]nonane-2,4-dione

The product from Preparation 83 (5.8 g), potassium cyanide (2.75 g) and ammonium carbonate (9.1 g) were heated in 80 mls of 50% aqueous EtOH for 7 h, and then at room temperature for 48 h. The mixture was filtered, and the solid washed thoroughly with water (3×50 mls). The filtrate was concentrated, the pH adjusted to 2 using concentrated HCl and the resulting suspension filtered off and washed with water (3×50 mls). The bulked solids were recrystallised from EtOH and water (300 ml:100 ml) to give the title product as 1:1 mixture of diatereoisomeric pairs (6.32 g); R_f 0.6 in EtOAc;

 ¹HNMR (300 MHz, CDCl₃) δ: 1.60-2.58 (m, 6H), 3.08-3.37 (m, 1H), 6.83-7.44 (m, 5H), 8.33 (d, 1H), 10.60 (s, 1H);