Ammonia → (S)-N-(Aminosulfonyl)-3-[[(1,1-dimethylethoxy)-carbonyl]amino]-2-oxo-1-azetidinecarboxamide, ammonium salt

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Reaction Steps

(S)-3-[[(1,1-Dimethylethoxy)carbonyl]amino]-2-oxoazetidine (5.1 g; see example 15A) was dissolved in a mixture of 160 ml of acetonitrile and 40 ml of dichloromethane. At -50° C. a solution of 5.4 g of chlorosulfonyl isocyanate in 30 ml of dichloromethane was added dropwise (15 minutes). The mixture was kept at -30° C. for 30 minutes. Then 64 ml of a solution of ammonia in acetonitrile (containing 2.4 g of ammonia)was added slowly at -10° to 0° C. The title compound precipitated together with inorganic material and was filtered by suction (crude yield 9.8 g). From the filtrate another crop of 2.7 g of crude title compound was obtained. According to thin-layer chromatography both fractions were of similar purity. The combined material was dissolved in 50 ml of water, adjusted to pH 6.5 by the addition of diluted aqueous ammonia and purified by chromatography on HP-20, eluting with water; 20 ml fractions were taken. Fractions 70-130 contained 2.7 g of the title compound.

Provenance & Evidence