m. p.=248-250GC (dec.; from methanol); [.ID= -129.' (DMSO, c = 1.00); 'H-NMR (D6-DMSO); t=4.13 and 4.18 (s, I-H+l'-H and s, 2 2-benzyl-H, or vice versa); MS: 520 (M+)]. The amino ketone ( 8 ) is probably first formed, being later aromatized by dimerization and air oxidation to yield ( 9 ) . The first step in this nucleophilic denitration and ring opening of ( I a ) and ( I b ) can be interpreted as SN2'-like attack by the nucleophiles H-, D -, Br-, N; and :NH, on C-2. In the reaction with LiAlH, the ulose first formed is hydrogenated to the compound (2) having an equatorial hydroxyl group1*], this reaction course being proved by reduction of (1 b ) with LiAID, and subsequent acetylation by acetic anhydride in pyridine to afford the homogeneous [2",3-D2]-2-deoxyglucoside ( 1 3) in more than 75 % yield; the [2',3-D2]-epimer could not be detected by NMR spectroscopy.
From the two following experiments it can be concluded that in the conversion of ( I a) into ( 4 j the attack of the bromide ion is not &-like but SN2'-like and that because of the A2-effectf91 the unstable 2"-bromo ulose is at once isomerized irreversibly to the 2'-bromo isomer ( 4 ) : 1. Treating ( 1 a ) with anhydrous lithium bromide in DzO-THF afforded the 2"-bromo-T-deuterio compound (7) as almost sole product. 2. Only the starting material ( 4 ) could be recovered from a solution of ( 4 ) in D20-THF containing lithium bromide and nitrite. It is probable that ( I a ) is converted into ( 5 ) analogously.