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dipolarophile, some diastereoselection was observed (6/3, 2:1), using 2ß as the nitrile oxide precursor. The nitrile oxide from 2a gave, on the other hand, a 1:1 mixture of separable diastereomers 6a.In conclusion, when one considers all of the other known ways to manipulate isoxazoles, such as ring metalation, as well as the variety of ring-opening processes known for the isoxazolium salts (especially the 5-unsubstituted derivatives),13 then numerous possibilities can be envisioned for the use of such nitrile oxides in the design of new C-nucleoside analogues. We further suggest that this general concept of constructing nitrile oxides containing sugars and sugar fragments should find broader applications in synthesis, for it is possible to effect carbon-carbon bond formation with creation of a masked /3-hydroxy ketone from a chiral fragment containing an -oxygen substituent.14This would, of course, be difficult to achieve through conventional carbanion chemistry because of competing ¡8-elimination processes. Other reports concerning this situation will be forthcoming.