DIASTEREOSELECTIVE ADDITIONS OF ORGANOLITHIUM AND ORGANOMAGNESIUM REAGENTS TO THE C=N BOND OF A CHIRAL, CYCLIC NITRONE DERIVED FROM ERYTHRULOSE

The reaction of the 3,4-O-isopropylidene-L-(S)-erythrulose with hydrox ylamine, followed by treatment of the resulting mixture of (E)- and (Z )-oximes with acetone and an acid catalyst, afforded two crystalline c hiral compounds. Through X-ray diffraction analysis, these products we re identified as a double acetonide derived from the (E)-oxime and a c yclic nitrone derived from the (Z)-oxime. The additions of organolithi um and organomagnesium reagents to the C=N bond of the nitrone were fo und to be diastereoselective. The addition products are useful interme diates for die preparation of alpha,alpha-disubstituted alpha-aminoaci ds and other nitrogen-containing compounds in enantiopure form. (C) 19 98 Elsevier Science Ltd. All rights reserved.