Arabin

Arabin-gummi, n. gum arabic. Sdure, /. arabio acid, arabin. 

Because synthesis of l-(2-deoxy-2-fluoro-)S-D-arabinofuranosyl)cytosine (744, FAC), an elementary arabino type of nucleoside having a growth-inhibitory effect against L 1210 leukemia in mice, through direct introduction of a fluorine atom in the 2 - up (arabino) position was difficult, compound 744 was prepared by condensation of trimethylsilylated A -acetylcytosine with 3-0-acetyl-5-(7-benzoyl-2-deoxy-2-fluoro-D-arabin-ofuranosyl bromide (742), which had been prepared by periodate oxidation of 6-0-benzoyl-3-deoxy-3-fluoro-D-glucofuranose (741). Similar condensa-... 

Many 5-alkyl-, 5-alkenyl-, and 5-alkynyl-l-(2-deoxy-2-fluoro- 5-D-arabin-ofuranosyl)pyrimidines (750 - 752 and 765 - 767) were prepared - " by condensation of 742 (or the equivalent, such as 743) with C-5-substituted pyrimidine derivatives, or by attachment of a C-fragment to C-5 of the existing nucleosides through their 5-iodo or 5-chloromercuri derivatives, or by further conversion of the attached C-5 substituent into another one. ... 

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. 

When 2,3-O-isopropylidene-D-gulono-1,4-lactone (52) was treated with sodium periodate, 3,4-O-isopropylidene-L-lyxurono-l,4-lactone (84) was formed26 this was converted in several steps into D-arabin-ose. Benzyl 2,4,5,6-tetra-O -benzyl-L-gulonate was oxidized to benzyl... 

The bromodeoxyaldonolactones have been used for the preparation of aminodeoxy aldonic acids and aminodeoxy sugars via azido derivatives (45,46). Likewise, a- and /J-aminopolyhydroxy acids have been prepared by treatment of the bromodeoxyaldonolactones with liquid ammonia (47). Thus, 3-amino-3-deoxy-D-threonic acid and 3-amino-3-deoxy-D-arabin-onic acid (40b) were obtained from 2-bromo-2-deoxy-L-threono- or D-xy-lono-1,4-lactone (38). It was shown that 2,3-epoxy carboxamides (namely, 39) are intermediates of the reaction. Heating at 90° for long periods led to the 3-amino-3-deoxyaldonamides, which upon acid hydrolysis yielded the corresponding aldonic acids. 

Apigenin-7-0-para-coumaroyl-glucoside Arabinic acid PF izz Arabinose pF izz Arabitol PF i ... 

Anhydro-l-deoxy-l,l-difluoro-D-ribitol21 (15) was, by an unusual ring-contraction, obtained from di-O-acetyl-D-arabinal (3,4-di-O-acetyl-l,5-anhydro-D-erythro-pent-l-enitol) (14) by way of the following reaction sequence. 

Also, di-O-acetyl-L-arabinal was converted into the corresponding anhydro-L-ribitol derivative (see also, pp. 195-197). 

The configuration of the products was established by periodate oxidation of the D compound, and reduction of the resulting dialdehyde to an optically active diol whose sign and magnitude of optical rotation ([a] ° +2.5° in water) correspond to that of the diol ([a]n° 46.8° in water) obtained by similar treatment of methyl a-L-arabinopyrano-side. The bis(p-nitrobenzoates) of the two diols exhibited similar relationships. Hence, it appears likely that the configuration at C-2 of the anhydride is the same as that at C-l of the L-arabinoside. The cis relationship of the hydroxyl groups was retained from the arabinal started with. 

Arabin, A., and Ostelius, J. (1980), Determination by electron-capture gas chromatography of mono(2-ethylhexyl) phthalate and di(2-ethylhexyl) phthalate in intravenous solutions stored in poly(vinyl chloride) bags,/. Chromatogra. B, 193,405 412. 

An aldonic acid dehydratase was partially purified,290 and found to convert D-fuconate into 3-deoxy-D-t/ reo-2-hexulosonate, and L-arabin-onate into the corresponding 3-deoxy-L-gZi/cero-2-pentulosonate. It did not act on L-fuconate or on D-galactonate. 

The several species of gums are distinguished by their behavior with water. Some dissolve in that liquid, and form mucilages, as gum-arabic while others soften and intumesce, as tragacanth. But there is also an intermediate kind, represented by cherry-tree gum, which is only partially dissolved in water. Those different classifications of gums have been denominated arabin, Irqgcuxmthin, and eerasin—from the Latin cerasus, a cherry-tree. 

GurnouuT states that neither arabin nor bassorin are present in gum-tragacanth, but that it is composed of on organised gelatmiform matter, very diverse, both chemically and physically, from gum-arabic, and which swells and divides in water, so as partially to traverse a filter. The same chemist considers the insoluble portion of tragacanth to be a compound of starch and lignin, and to have, in no respect, the same properties with bassorin. 

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