Reaction with diethylaminosulfur

In addition to the perfluoroalkylzinc compounds, the zinc reagent formed from 1,1,1-trifluorotrichloroethane has received considerable attention. This zinc compound was first reported as a stable ether complex [56]. Later, the DMF complex was isolated and the structure was determined by X-ray diffraction and shown to be monomeric [57] (equation 50). This zinc reagent undergoes a variety of functionalization reactions, and some typical examples are illustrated in Table 2 [47, 58, 59, 60, 61] The alcohol products (Table 2) can be converted to AiCF=CXCF3 (X = Cl, F) by further reaction with diethylaminosulfur trifluoride (DAST) and l,8-diazabicyclo[5 4.0]undec-7-ene (DBU) [60]... 

In the reaction with diethylaminosulfur trifluoride, halogenated acetaldehydes preferentially form bis(l-fluoro-2-polyhaloethyl) ethers. ... 

Some ketoses and aldoses undergo rearrangement upon reaction with diethylaminosulfur trifluoridc. In 2-uloses, the axial orientation of an a-methoxy group can give rise to its 1,2-migration, cf. formation of 9 and 10. Thus, l,2-difluoro-2-alkoxy sugars arc obtained as anomcric mixtures. 

For similar 1,5-migrations of methoxy groups in pentofuranoses. sec ref 78. 3-Uloses give only moderate yields in reactions with diethylaminosulfur trifluoride due to fragmentation... 

OH —> F. 7-Dehydro-25-hydroxycholesteryl acetate has been converted into the 25-fIuoro derivative by reaction with diethylaminosulfur trifluoride (757o yield) the product was converted into 25-fluorovitamin D3 by irradiation. ... 

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