4- Deoxy-hexoses synthesis

In extending this direct method of synthesis, we next investigated the possibility of preparing similarly constituted halides from 2-deoxy-D-arabino-hexose (2-deoxy-D-glucose) (21). The hexose was subjected to a partial anomerization procedure described by Bergmann and co-workers (1). The solid material obtained by this procedure is a mixture of the anomeric forms of 2-deoxy-D-arabino-hexose low temperature p-nitro-benzoylation of the latter in pyridine resulted in a mixture of crystalline, anomeric tetrakis-p-nitrobenzoates in a ratio of approximately 1 1. They were readily separable by fractional recrystallization, and treatment of either with an excess of hydrogen bromide in dichloromethane, or with... 

The bromide (5) failed to couple with dialkoxypyrimidines, even at elevated temperatures the failure is probably because of steric conditions imposed by the axially oriented C-4 p-nitrobenzoyloxyl group (see structure 5) this same group in the other halides (la, lb, 2a, 2b, 4a, and 4b) discussed in the foregoing is an equatorial substituent. Accordingly, the preparation of a differently constituted halide of 2-deoxy-D-Zt/xo-hexose is being investigated for the synthesis of pyrimidine nucleosides. 

Synthesis of Ring-Deoxy Sugars (Pseudo-Hexoses)... 

An important step in the synthesis of paratose (3,6-dideoxy-n-rtfoo-hexose) involved the conversion of methyl 3-chloro-3-deoxy-/8-D-allopyranoside into methyl 3,6-dichloro-3,6-dideoxy-/8-D-allo-pyranoside in 33% yield.359... 

N-Acetvlneuraminic Acid Aldolase. A new procedure has also been developed for the synthesis of 9-0-acetyl-N-acetylneuraminic acid using the aldolase catalyzed reaction methodology. This compound is an unusual sialic acid found in a number of tumor cells and influenza virus C glycoproteins (4 ). The aldol acceptor, 6-0-acetyl-D-mannosamine was prepared in 70% isolated yield from isopropenyl acetate and N-acetyl-D-mannosamine catalyzed by protease N from Bacillus subtilis (from Amano). The 6-0-acetyl hexose was previously prepared by a complicated chemical procedure (42.) The target molecule was obtained in 90% yield via the condensation of the 6-0-acetyl sugar and pyruvate catalyzed by NANA aldolase (Figure 6). With similar procedures applied to KDO, 2-deoxy-NANA and 2-deoxy-2-fluoro-NANA were prepared from NANA. 

Deoxy-D-arabino-hexose 3% HiEff8-BP 200 synthesis of 2-deoxy-L-erythro-and -D-fhreo-pentose 390... 

Another substrate for the synthesis of hexoses, frons-5,6-dihydro-6-(hydroxymethyl)-2-methoxy-2/7-pyran (211), was obtained in both optically active forms by resolution of its 6-camphanyl ester.1 2 From the levorotatory enantiomer, methyl 2,3,6-tri-0-acetyl-4-deoxy-a-D-.r //o-hexopyranoside (606) was synthesized, thus confirming its (2S) (6S) configuration, corresponding to the D configurational series. 

S. S. Thomas, J. Plenkiewicz, E. R. Ison, M. Bols, W. Zou, W. A. Szarek, and R. Kisilevsky, Influence of monosaccharide derivatives on liver cell glycosaminoglycan synthesis 3-deoxy-D-xylo-hexose (3-deoxy-o-gaIactose) and methyl (methyl 4-chloro-4-deoxy- 3-D-galacto-pyranosid)uronate, Biochim. Biophys. Acta 1272 37 (1995). 

G. Siewert and O. Westphal, Substitution of secondary p-tolylsulfonyloxy groups by iodine. Synthesis of 4-deoxy- and 4,6-dideoxy-D-xylo-hexose, Liebigs Atmalen der Chemie 720 161... 

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