2,3,4-Tri-O-acetyl-a-D-arabinopyranosyl

T Kinoshita, Y Kasahara, N Nimura. Reversed-phase high-performance liquid chromatographic resolution of non-esterified enantiomeric amino acids by derivatization with 2,3,4,6-tetra-O-acetyl-P-D-glucopyranosyl isothiocyanate and 2,3,4 tri-O-acetyl-a-D-arabinopyranosyl isothiocyanate. J Chromatog 210, 77, 1981. 

By following the reported procedure, coupling reaction of 70 and 2,3,4-tri-O-acetyl-a-L-arabinopyranosyl bromide in the presence of AgOTf and tetramethy-lurea (TMU) gave the coupled product (72) in 73% yield. Finally, treatment of 72 with K2CO3 in MeOH provided the synthetic phenethyl 6-O-a-L-arabinopyranosyl-p-D-glucopyranoside (66) in 86% yield. 

Nitrogen-, Sulfur- and Selenium-containing Compounds.- 2,3.4-Tri-O-acetyl-P-D-arabinopyranosyl azide, 5 the azido orthoester 15, the diazirine 16, episulfide 17, selenourea 18, a-D-ribopyranosylamine l,3-(cyclic carbonate), lactams 19a/b and 20, the 6-nitro-7-methylthioheptitol 21,2-acetamido-2-deoxy-P-D-glycopyranosyl nitromethane (3-... 

C H NO , 2-Acetamido-2,3,-dideoxy-5,6-0-isopropylidene-D-threo-hex-2-enono-1,4-lactone, 44B, 399 C11H15N3O7, Tri-O-acetyl-a-D-arabinopyranosyl azide, 40B, 391 C11H15N3O7, Tri-0-acetyl-/3-D-xylopyranosyl azide, 42B, 320 Cl1H1gOa f 1-Deoxy-2-C-phenyl-D-arabinitol, 44B, 400 Cl1H1gOg, Methyl 4,6-di-0 acetyl-2,3-dideoxy-a-D-threo-hex-2-eno-pyranoside, 45B, 466... 

The conformations of the o- and /3-anomers of 2,3,4-tri-Q-acetyl-D-arabinopyranosyl azide have been predicted from semi-empirical quantum chemical calculations. Neutral Raney nickel has been used to convert a glycosyl azide to the corresponding glycosylamine in the presence of Q-benzyl protecting groups. " CHaOSi. ... 

In the pentose series, attack has also been observed to occur mainly from the less-hindered side of the double bond, as in the addition of trifluoro(fluoroxy)methane to di-O-acetyl-D-arabinal. Trifluoromethyl 3,4-di-0-acetyl-2-deoxy-2-fluoro-/3-D-arabinopyranoside and 3,4-di-0-acetyl-2-deoxy-2-fluoro-/J-D-arabinopyranosyl fluoride were obtained,72,74 together with a very small proportion of 3,4-di-0-acetyl-2-deoxy-2-fluoro-a-D-ribopyranosyl fluoride.74 With di-O-acetyl-D-xylal, however, the lyxose derivatives were mainly obtained.72,73 The suggestion has been made73 that the greater conformational mobility of pentopyranoses results in a preponderance of the C d) conformer of the D-lyxose derivatives,72,73 such that F-l and CFsO-l are axially disposed. For further reactions of unsaturated carbohydrates with tri-fluoro(fluoroxy)methane, see Section 11,9. 

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