Hydrazine → TERT-BUTYL 3-OXOPYRAZOLIDIN-4-YLCARBAMATE

Participants

Reaction Steps

Under a nitrogen atmosphere, dry methylene chloride (50 ml) was cooled in an ice bath and anhydrous hydrazine (97%, 11.0 g, 333 mmole) was added. The ice bath was removed and the solution was stirred until it warmed to room temperature. At this time a solution of methyl 3-(p-toluenesulfonyloxy)-2-(S)-(t-butoxycarbonylamino)propionate (20.0 g, 53.6 mmole) in dry methylene chloride (50 ml) was gradually added. The reaction solution was stirred under nitrogen at room temperature for 5 hours. The solution was then concentrated under reduced pressure and the concentrate was taken up in saturated aqueous sodium bicarbonate solution. The aqueous solution was continuously extracted for 14 hours with methylene chloride (700 ml). The methylene chloride solution was dried over sodium sulfate, filtered and concentrated under reduced pressure to yield approximately 5.15 g, 48% of 4-(R,S)-(t-butoxycarbonylamino)-3-oxo-1,2-diazolidine: n.m.r. (CDCl3, 90 MHz): δ7.04 (m, 1), 5.12 (m, 1), 4,28 (m, 1, C-4 proton), 3.94 (m, 1, C-5 proton), 3.20 (m, 1, C-5 proton), 1.45 (s, 9, t-butyl protons); i.r. (CHCl3): 3430, 3250, 3019, 2983, 1702, 1545, 1503, 1370, 1297, 1241, 1215, 1165 cm-1 ; f.d.m.s.: M+ =201;

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