Dimethylaminosulfur trifluoride

Other useful dehydrating agents are dimethylaminosulfur trifluoride (DAST), methyl A -(triethylammoniosulfonyl)carbamate (Burgess salt), acetic anhydride, oxalyl chloride, and phosphorous oxychloride, each one in combination with triethylamine (89). Dehydration of O-sUylated hydroxamic acids using trifluoro-methanesulfonic anhydride and triethylamine under mild conditions also gave nitrile oxides, which in the presence of olefins led to the formation of 2-isoxazolines in moderate to good yields (90). In view of the less readily available starting materials, this method probably will be of limited use. 

Dimethylamino)trimethylsilane (29.3 g, 0.25 mol) was added dropwise to a stirred solution of dimethylaminosulfur trifluoride (33.2 g, 0.25 mol) in anhyd CFC13 (100 mL) at — 78 CC. Once the addition was complete, the mixture was allowed to warm slowly to rt, then stirred for a further 10 min and filtered under N2. The filtrate was evaporated to dryness under reduced pressure to give the title compound yield 23.5 g (60%) mp 64-65 "C. 

Diammonium phosphate 4, 6-Diamidino-2-phenyUndole dihydrochloride 4,4 -Diaminostilbene-2,2 -disulfonic acid N,iV-Diethylaminosulfur trifluoride iV,iV-Dimethylaminosulfur trifluoride Diethylaluminium 2,2,6,6-tetramethylpiperidide... 

Detection of the alko) (dimethylamino)sulfur difluoride intermediate of 2 -deoxy-5 -0-dimetho) itylcytidine has been recently reported by K. Agyei-Aye, S. Yan, A.K. Hebbler, and D.C. Baker, Preparation of 2,3 -anhydropyrimidine nucleosides using N,N-dimethylaminosulfur trifluoride (DAST). Nucleosides Nucleotides 8 327(1989). 

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