Ethyl fluorosulfate

Treatment of heterocyclic ketones 22 with ethyl fluorosulfate leads to tellurapyrylium salts 25a (82JOC5235 87JOC2123), and interaction with Meldrum s acid produces compounds 29. 

Alkylation of tellurapyrones 22 (82JOC5235 86MI2 87JOC2123) and tellurachromones 55 (83JA883 88MI4) with ethyl fluorosulfate occurred at the carbonyl oxygen atom of 4-alkoxy derivatives of 25a and 75. 

Diorgan o-4- ox o-4//-tellurin s were converted to tellurinium salts on treatment with ethyl fluorosulfate or 4-dimethylaminophenyl magnesium bromide1-3. 

Diphenyl-4-ethoxytellurinium Fluorosulfate1 0.98 g (2.7 mmol) of 2,6-diphcnyl-4-oxo-477-tcllurin are added to 4 ml of freshly distilled ethyl fluorosulfate and the mixture is heated under nitrogen on a steam bath until a clear solution is obtained. The flask is then held in a water bath at 60° for 5 min, the mixture is cooled, triturated with 90 ml of diethyl ether, and the air- and moisture-sensitive yellow solid is filtered off yield ... 

Oxo-4//-l-benzotellurines were reduced by diisobutylaluminum hydride to 4//-1-benzotellurins (p. 821) and were converted by treatment with ethyl fluorosulfate to benzotellurinium salts (p. 828)2. 

F.thoxy-7-methoxy-2-phenyl-l-benzutcllurinium Fluurosulfate2 5.0 g (14 mmol) of 2-phenyl-7-methoxy-4-oxo-477-1-benzotellurin are added to 20 m/] of freshly distilled ethyl fluorosulfate, the mixture is stirred under nitrogen at 60° for 10 min, cooled to 20°, and 200 ml] of diethyl ether are added. The red solid is filtered off and recrystallized from acetonitrile yield 6.0 g (87%) m.p. 216". 

Oxo-4/7-l-benzotellurines reacted with boron trifluoride, phosphorus pentafluoride, and ethyl fluorosulfate to give 1-benzotellurinium salts. 

It is interesting and unexpected that diazoethane reacts in a different way under similar conditions (2-3) (McGarrity et al., 1980). In FS03H-SbF5-FS02Cl, only ethyl fluorosulfate (2.8) and the N-protonated diazenium ion (2.9) are observed the C-protonated diazonium ion (2.7) is not detected. 

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