Lyxofuranoside preparation

DL-Dihydrostreptose and its ribo isomer were similarly obtained. Birch reduction of 2-methyl-3-furoic acid, followed by addition of methanol, bromination, and dehydrobromination, gave 402 as a mixture of the isomers. Hydroxylation of 402 with osmium tetraoxide-so-dium chlorate, and subsequent treatment with acetone-sulfuric acid afforded three isomeric acetals (403-405). The structures of these compounds were assigned on the basis of their H-n.m.r. spectra. In addition, the relationship between 403 and 404 was established by hydrolysis and reglycosidation. The methyl esters 403-405 were quantitatively reduced to the corresponding alcohols. The mixture of alcohols obtained from 403 and 404 was converted into crystalline 5-deoxy-3-C-(hydroxymethyl)-l,2-0-isopropylidene-a-DL-ribofuran-ose (406), which was compared directly with a sample prepared from D-xylose. Methyl 5-deox y-3-C-(hydroxy methyl)-2,3-O-isopropy lidene-/3-DL-lyxofuranoside (407), obtained by reduction of 405 with lithium aluminum hydride, was hydrolyzed with dilute hydrochloric acid, to give a,/3-DL-dihydrostreptose.2,ifi... 

V. S. Murthy, A. S. Gaitonde, and S. P. Rao, One-pot conversion of 1,2-diols to epoxides —convenient preparation of methyl 2,3-anhydro-5-0-trityl-/ -D-lyxofuranoside and methyl 2,3-anhydro-4,6-0-benzylidene-a-D-mannopyranoside, Synth. Common., 23 (1993) 285-289. 

In connection with carbohydrates, (1,5,3,5,5W)-1,3-dimcthyl-2,9-dioxabicyclo 3.3.11 nonane has been prepared from dithiane and D-glucose263. An epoxide derived from D-xylose 195 has been opened regioselectively by means of compound 161 at the 4-position in 90% yield264. In the case of the methyl 2,3-anhydro-a-D-lyxofuranoside 196 the ring... 

Walker et al. have described by tliis method a seven-step synthesis of 4-thio-2-deox-y-i3-eri f/7ro-pentosc (37) from 2-dcoxy-D-erir/ira-pentosc via dithioacetals 35 and 36, involving inversion at C-4 by Mitsunobu reaction and final cyclization of the dithioacetal, accompanied by further inversion at C-4. Secrist et al.- have synthesized 39 from the ribose derivative 38 using the same method. Similarly, Imbach et al. have prepared 1,4-dithio-D-ribofuranosides 39 from L-lyxose and from D-ribose,and 1,4-dithio-L-lyxofuranosides 40 from D-ribose. Mackenzie... 

The C26—C37 fragment 15 of calycufin C has been synthesized from methyl 2,3-di-(9-benzyl-a-D-lyxofuranoside (4), " prepared from D-lyxose (Scheme 1). Methylation of... 

A study of the stability of compounds derived from D-glucose and D-fructose with boric acid or phenylboronic acid has found that the stability constants for the fructose compounds are much greater than those for the glucose compounds. The synthesis of crystalline 3-0-acetyl-2,4-0-phenylboranediyl- -D-ribopyranosyl bromide in a two pot process from D-ribose has been described along with some of its selective glycosylation reactions. Ethyl (dimethoxy)borane has been used in the synthesis of anomerically pure furanosides from the free sugars. Thus methyl 2,3-0-ethylboranediyl-tt-D-lyxofuranoside was prepared and then de-esterified under essentially neutral conditions to the glycoside in 80%... 

Derivatives of the biologically inqxrrtant disaccharide sequence P-D-Galp-(l- 3)-D-Gal, e.g., compounds (69) and (70), were prepared firom laminaribiose octaacetate (67) in seven steps via the ditriflate (68). An inqnoved synthesis of 23-anydro-a- and -P-D-lyxofuranosides... 

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