Hexopyranoses dideoxy, synthesis

Hexamine — see Hexamethylenetetramine 1,4,7,10,13,16-Hexaoxacyclooctadecane — see [18]Crown-6 Hexazinone as herbicide, 1, 187 Hex-2-enopyranoside, 2,3-dideoxy-synthesis, 1, 464 Hexobarbital, 3, 150 Hexogen, 3, 530 a-D-galacto- Hexopyranose nomenclature, 1, 31 Qf-D-ido-Hexopyranose nomenclature, 1, 31... 

Dideoxy-D-eryt/zro-hexopyranose (172) has been obtained from 3-deoxy-D-eryt/zro-pentose (171, Scheme 51)248 as an intermediate for the synthesis of the lactone moiety of inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A reductase, that lowers cholesterol levels. 

P.-T. Ho and S. Chung, Synthesis of 2,4-dideoxy-D-eryi/tro-hexopyranose. An intermediate for synthesis of the lactone moiety of inhibitors of hydroxymethylglutaryl-coenzyme A reductase, Carbohydr. Res., 125 (1984) 318-322. 

J. Karban, M. Budesinsky, M. Cerny, and T. Trnka, Synthesis and NMR spectra of l,6-anhydro-2,3-dideoxy-2,3-epimino- and l,6-anhydro-3,4-dideoxy-3,4-epimino-/i-D-hexopyranoses, Collect. Czech. Chem. Commun., 66 (2001) 799-819. 

Reductive cyclization by lithium aluminum hydride as the key step has been employed for the preparation of O-benzylated l,6-anhydro-2,3-dideoxy-2,3-epi-mino- and l,6-anhydro-3,4-dideoxy-3,4-epimino-p-D-hexopyranoses having the alio-, manno-, galacto-, and to/o-configurations from suitable 1,6 2,3- and l,6 3,4-dianhydro-p-D-hexopyranoses. Stereoselective trara-diaxial cleavage of the oxirane ring was effected by treatment with sodium azide and ammonium chloride in a 2-methoxyethanol-water mixture at 110-120 °C. Synthesis of 1,6-anhydro-4-(9-benzyl-2,3-dideoxy-2,3-epimino-p-D-marmopyranose (7) from di-anhydro derivative 4 illustrates this methodology. An alternative reduction by sodium borohydride in THF was also tested in the preparation of the 2,3-d-u//o-and D-ma u-epimines in this series. It provided a better yield (73%) than... 

Methyl 2Z,5-hexadienoate (126) undergoes cyclization to / S-parasorbic acid when treated with polyphosphoric acid. Torssell and his co-workers employed the substrate thus obtained for a new series of sugar synthesis. OL-Desosamine was synthesized in an essentially similar way to that described above. Analogously, DL-chalcose (127, 4,6-dideoxy-3-0-methyl-DL-xy/o-hexopyranose), was obtained, that is, by oxirane ring opening in racemic epoxy-lactone 122 with methanol in the presence of p-toluene-sulfonic acid. 

The two methyl pyranosides of 2-acetamido-2,3.4-trideoxy-D-er> f TO-hexose have been prepared as intermediates in the synthesis of purpurosamine C. The crucial intermediate in this synthesis was l,6-anhydro-3,4-dideoxy-2-0-tosyl- 8-D-t/zreo-hexopyranose (14) which underwent displacement of the sulphonyloxy... 

The synthesis of 2-acetamido-1,6-anhydro-2,3-dideoxy-B-D-rlbo-hexopyranose from a 3-thlo-sugar by reductive desulphurization is covered in Chapter 9. Reduction (NaBH ) of secondary mesylates with a vicinally related trans-dlallylamlno group proceeds to give deoxygenated products via aziridinium ion intermediates, sequence, sometimes the product is that of amino migration examples are detailed in Chapter 9. 

The total synthesis of all four 3,6-dideoxy-DL-hexoses and all four 3-deoxy-DL-hexoses has been achieved by stereospecific hydroxylations of butyl 2-acetoxy-tra j -hex-4-enoate and butyl 2-acetoxy-6-hydroxy-tran5-hex-4-enoate, respectively. In an alternative synthesis 3,6-dideoxy-DL-arabino- and -DL-ribo-hexopyranoses were prepared from the Diels-Alder adduct derived from methyl... 

The amide 24, an intramediate in synthesis of methyl 4,6-dideoxy-4-(3-deoxy-L-g(ycero-tetronamido)-a-D-truuinopyranoside, t-butyl-NA -dibenzyl-2-(l,2 5,6-di-0-isopropylidene-a-I>-allofuranose-3-yl)-L-glycirutle 25, 3 2-deoxy-2-hydroxyimino derivatives 26 and 27 of fi-D-arabino-hexopyranose, and 23,4,S-tMra-0-ace l-6-amino-6-deoxy-D-galactonolactam.9S TheN-glycosidic... 

All four diastereomeric 2-acetamido-2,4-dideoxy-D-hexopyranoses have been synthesized from the (5)-malic acid derived four-carbon aldehyde (37) (Scheme 11) as potential inhibitors of A/-acetylneuraminic acid synthase. The intermediates involved in the synthesis of the v-arabino-isomer (38) are shown in Scheme 11. The two vinyl Grignard addition reactions provided separable equimolar mixtures of C-3 epimers the analogous reactions applied to these yielded the three other isomeric amino-sugars. iV-Acyl-derivative (40) of L-daunosamine has been synthesized from the C-4-carboxy-branched intermediate (39), obtained by a stereoselective enolate-imine condensation (Scheme 12). The C-4-epimeric L-acosamine derivative was obtained by a similar sequence when compound (39) was first epimerized at C-4 (LiOH-HjO-MeOH). ... 

Procedures for the preparation of a-D-glucopyranose 1-phosphate from potato starch and for the synthesis of 4,6-dideoxy-a- and - -L,-lyxo-hexo pyranose 1-phosphates and 2,6-dideoxy-cx-L-flra6/ o-hexopyranose 1-phosphate have been described. The orthoesters (73) and (74) were stereospecifically... 

Paulsen s group has reported the synthesis of derivatives (256) and (257) of the hydroxyethyl-branched octose that is found as a component of the quinocycline complexes isolated from Streptomyces aureofaciens. The route from the epoxyketone (255) is outlined in Scheme 59. An identical route was used to prepare branched-chain analogues in the o-series, in which it was shown that acid-catalysed methanolysis of the hydroxyethyl-branched derivative (258) yielded the more stable isomer (259) via the anhydro-sugar d-(257). Paulsen s group has also described a synthesis of a derivative (260) of pillarose (see Vol. 9, p. 99), a component of the antibiotic pillaromycin, using the dianion (261) prepared from 2-hydroxymethyl-l,3-dithiane to introduce the branch at C-4 (Scheme 60). A similar approach, using the anion derived from 2-methyl-l,3-dithiane, and subsequent desulphurization and reduction, etc., was adopted in a synthesis of a derivative (262) of aldgarose (4,6-dideoxy-3-C-[(i )-l-hydroxyethyl]-D-W6o-hexopyranose 3,3 -cyclic carbonate) (cf. Vol. 8, p. 100). 

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