1159599-99-1

13573-28-9

144-62-7

1159599-99-1

General procedure for the synthesis of 2-oxa-6-azaspiro[3,3]heptane oxalate from 6-(p-toluenesulfonyl)-2-oxa-6-azaspiro[3.3]heptane and oxalic acid: to a solution of 6-(p-toluenesulfonyl)-2-oxa-6-azaspiro[3.3]heptane (7.5 g, 29.6 mmol) in 500 mL of methanol, magnesium scrapings were added (5.04 g 207 mmol) and the reaction mixture was sonicated for 1 hour. Subsequently, the solvent was removed by evaporation and 1 L of diethyl ether and sodium sulfate decahydrate (4.21 g, 29.6 mmol) was added to the residue and stirred for 1 hour at room temperature. The reaction mixture was filtered through diatomaceous earth and the filtrate was dried with anhydrous sodium sulfate. After addition of anhydrous sodium sulfate, oxalic acid (1.33 g, 14.80 mmol) dissolved in 2 mL of ethanol was added and stirred for 5 min to give 2-oxa-6-azaspiro[3,3]heptane oxalate (1.5 g). Yield: 51.1%; Appearance: off-white solid; 1H NMR (300 MHz, DMSO-d6) δ (ppm): 4.65 (s, 4H, 2CH2, spiro-morpholine), 4.16 (s, 4H, 2CH2, spiro-morpholine); LC-MS (ESI + ve) m/z 100.0 [M + H]+.