Glucosides, acetals

Yadava, V. S., and K. Misra. Vanilloyl-1-O-beta-D-glucoside acetate from the roots of Saccharum offidnarum. Indian J Chem Ser B 1989 28(1) 875-877. Morita, L, S. Morishita, T. Tatsumi, and S. Kako. Invert sugar having high inversion. Patent-Japan Kokai-74 134,852 1974. 

The formation of acetals allows a remarkable degree of control over the chemistry of sugars. Apart from the simple glucoside acetal we have just seen, there are three important acetals worth understanding because of the way in which they illustrate stereoelectronic effects—the interplay of... 

A variation of the Helferich reaction (see Section III, 2), which might be of practical use under certain circumstances, is illustrated by the preparation of phenyl tetra-O-acetyl-a-D-glucopyranoside from the methyl a-D-glucoside acetate by fusion with phenol and zinc chloride the yield of the phenyl a anomer was 55 %, and some of the phenyl /3 anomer (15 %) was also isolated. 

Figure 2.14 shows the peaks of the 16 anthocyanins typical of the Vitis vinifera varieties 3-glucosides, 3-glucoside acetates, 3-glucoside ptmz-coumarates and malidin 3-glucoside caffeate. The elution sequence of compounds from a reverse phase column is due to their polarity and is always the same, even if a different column is used. 

Carbohydrate acetals are generally called glycosides (see the following mechanism), and an acetal of glucose is called a glucoside. (Acetals of mannose are mannosides, acetals of fructose are fructosides, and so on.)... 

Detailed analysis of the n.m.r. spectrum of 3,6-anhydro-a,a-trehalose hexa-acetate using methyl 3,6-anhydro-a-D-glucoside acetates and methyl 2,3,4,6-tetra-O-acetyl-a-D-glucoside as models has shown that the anhydro-ring is in a distorted Ci(d) conformation and the other ring is in a Ci(d) form. ... 

I the glucosides are similar in chemical nature j to the acetals, e.g, CH3CH(OC2Hs)2, which... 

The configuration of the glucoside linkage is different in the two, however. Structures [I] and [II], respectively, illustrate that the linkage is a /3-acetal-hydrolyzable to an equitorial hydroxide—in cellulose, and an a-acetal-hydrolyz-able to an axial hydroxide—in amylose, a starch ... 

Terpene glucosides chloroform — methanol (80 + 20). Arbutin ethyl acetate — methanol — water (100 + 17 + 14). 

Methylene Iodide, 1, 57 7, 90 0-Methyl Esculetin, 4, 45 df-METHYL Ethyl Acetic Acid, 5,75 Methyl formate, 3, 67 a-M ETHYL d-GLUCOSIDE, 6, 64... 

The structures of all products were determined by either conversion to the corresponding acetates or direct comparison with the corresponding natural p-glucosides. Identification of the -configuration of the anomeric center was easily achieved via the analysis of the C-H/C-H coupling constant. The synthetic (3-D-glucosides (30, 33, 34, 35 and 36) were identical with... 

The synthetic 31 was converted to the cyanoglucoside osmaronin (41a) which was isolated from a methanolic extract of the leaves of Osmaronia cerasi-formis. Acetylation of 31 gave an acetate (99% yield) which was subjected to ozonolysis to afford a ketone 42. The Horner-Emmons reaction of 42 using diethyl cyanomethylphosphonate furnished (Z)-43a (22% yield from the acetate of 31) and ( )-43b (10% yield from the acetate of 31). Deprotection of (Z)-43a and ( )-43b gave the (3-D-glucosides 41a (83% yield) and 41b (94% yield), respectively. The spectral data of the synthetic 41a were identical with those ( H- and C-NMR) of the natural osmaronin (41a) (Fig. 5). 

Figure 2. Linear regression plot of root growth inhibition of tomato and radish seedlings by o and -hydroxyphenyl) acids. o-Hydroxycinnamic acid, (o-hydroxyphenyl) acetic acid ( ) melilotic acid, 2-(o-hydroxyphenyl) butanoic acid ( ) o-hydroxy-benzoic acid, ( -hydroxypheny 1 )acetic acid (0) -hydroxycinnamic acid, =hydroxybenzoic acid, 3-( -hydroxyphenyl) propanoic acid (X) o-coumaryl glucoside, water control (----) (1 ). ...

Peterlin168 has shown that the viscometric data for potato amylose acetate in chloroform solution can be readily interpreted in terms of a random-coil model for the molecule, in which there is hindered rotation at the oxygen atom of the glucosidic linkage. 

Lack of selectivity in the reaction of the /3-D-glucoside derivative with one molar equivalent of benzylthiocarbonyl chloride has also been noted 40% of the 2,3-diester and 40% of the starting material were isolated.40 Similarly, unimolar benzoylation of phenyl 4,6-0-benzylidene-/3-D-glucopyranoside gave only 9% of the 3-ester, together with 47% of the 2,3-diester.41 Acylation of benzyl 4,6-0-benzylidene-/8-D-glucopyranoside with acetic anhydride-pyridine-pyridine hydrochloride yielded,42 in contrast to the reaction with the... 

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