Lyxose 5-deoxy-3-

Deoxy-D-(2-2H)lyxose (substituted) or (2S)-2-deoxy-D-fhreo-(2-zH)pentose 

D-Lyxose yielded a D-lyxosyl chloride 2,3,4-tri(chlorosulfate) which, on treatment with chloride ion, led to a dichlorodideoxy compound, most probably 2,4-dichloro-2,4-dideoxy-L-arabinose.353 D-Glucose gave a compound presumed to be 4,6-dichloro-4,6-dideoxy-a,/3-D-galactosyl chloride 2,3-di(chlorosulfate),360 and D-xylose afforded a monochloromonodeoxy derivative formulated, on indirect evidence, as 4-chloro-4-deoxy-L-arabinopyranosyl chloride 2,3-di(chlorosulfate).360 3,4-Dichloro-3,4-dideoxy-/3-D-ribopyranosyl chloride 2-(chlorosulfate) was the major, and 4-chloro-4-deoxy-a-D-xylopyranosyl chloride 2,3-di(chlorosulfate) the minor, product from the reaction of L-arabinose with sulfuryl chloride at room temperature for 24 hours.357,361 It has been established that, on reaction with sulfuryl chloride at low temperature, crystalline a-D-xylopyranose and /3-D-lyxopyranose afford, respectively, the 2,4,6-tri(chlorosul-fate)s of /3-D-xylopyranosyl chloride and a-D-lyxopyranosyl chloride,362 363 confirming that substitution at C-l occurs by an Sn2 process on a l-(chlorosulfuric) ester intermediate. 

Barium D-ribose 5-phosphate pentahydrate75 2-Deoxy-D-cry[Pg.363]

Fucosidase inhibiting l,4,5-trideoxy-l,4-imino-L-lyxitol (78) was prepared [124] from D-ribose via protected 5-amino-5-deoxy-L-lyxose (79) by a chemical route. This compound, as well as the 1-aminomethyl homologue (80), obtained by Kiliani-Fischer chain extension of (79), inhibited a-L-fucosidase with K around 2 pmol/1. l,4-Dideoxy-l,4-imino-D-iditol (81) [71] was found to be a moderate inhibitor of the enzyme. 

The Wohl degradation214 of suitably acetylated aldononitriles was used for the synthesis of 5-deoxy-L-arabinose,216 5-deoxy-D-lyxose,2W and 5-deoxy-D-ribose.217 

The action of (p-nitrophenyl)hydrazine on 3,4-di-0-acetyl-2-bromo-2-deoxy-D-xylopyranose (62) leads79 to two (p-nitrophenyl)hydrazones, namely, 3,4-di-0-acetyl-2,5-anhydro-D-xylose (p-nitrophenyl)hydra-zone (63) and 3,4-di-0-acetyl-2,5-anhydro-D-lyxose (p-nitrophenyl)-hydrazone (64). Simultaneous formation of the two compounds, unex- 

The chlorosulfated glycosyl chlorides 27 and 28 were converted into 2-chloro-2-deoxypentoses on treatment with aluminum chloride [50], In the case of 27, the use of 1.5 mol-equivalents gave exclusively the 2-chloro-2-deoxy-a-D-lyxopyranosyl chloride 3,4-di(chlorosulfate) 29 treatment of 29 with sodium iodide yielded crystalline 2-chloro-2-deoxy-D-lyxose. Similarly, 28 afforded 2-chloro-2-deoxy-a-D-xylopyranosyl chloride 3,4-di(chlorosulfate) (30 Scheme 7). 

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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