Tosyloxy group replacement

Replacement of one tosyloxy group m 2-fluoro-2-nitro-l,3-propanediol ditosylate by azide ion occurs easily [S5] (equation 75)... 

At 1650, both tosyloxy groups in 108 were replaced with inversion, and the bis(dimethylamino)-D-glucitol derivative was obtained. On heating isosorbide (3) or its diacetate (111) in the presence of such dehydrating agents as aluminum oxide in a Pyrex-glass tube above 400°, the doubly unsaturated compound 112 is formed in —50% yield194 (see Scheme 23). 

The iodo derivative is a useful intermediate for the preparation of a wide variety of different types of compounds. Primary mesyl esters also react with sodium iodide in acetone, but the selectivity of this cleavage is less because of the greater reactivity of secondary mesyl esters. oa( ) Methyl 2,3,4-tri-0-acetyl-6-0-mesyl-a-D-glucopyranoside is converted into methyl 2,3,4,6-tetra-O-acetyl-a-D-glucopyranoside with acetic anhydride and potassium acetate. Replacements of a primary mesyloxy group with fluorine by use of potassium fluoride in methanol,106 with chlorine by use of lithium chloride,102 and with pyridine to form a pyri-dinium deoxy derivative,106 have been reported. Primary tosyloxy groups have been replaced by hydrogen,106 by thiocyanate,107 and by... 

In contrast, the 6-tosyloxy group of l,6-di-0-tosylketohexofuranose derivatives is more readily replaced by iodine. Thus, by reaction during 24 hours at 90-100°, 2,3-0-isopropylidene-l,6-di-0-tosyl-L-sorbose gives264 the corresponding 6-deoxy-6-iodo-l-0-tosyl derivative (possibly accompanied by some unisolated l,6-dideoxy-l,6-diiodo derivative) and 2,3-0-isopropylidene-l,6-di-0-tosyl-D-fructose behaves266 similarly (16 hours at 100°). 

Cyclic acetals of the naturally occurring N-ribofuranosides have been prepared. Levene and Tipson156 found that inosine will condense with acetone in the presence of zinc chloride to give a monoisopropylidene derivative. Since this compound afforded a monotosyl ester in which the tosyloxy group was readily replaced by iodine, it was assigned structure CYI. Phosphorylation of CYI followed by hydrolytic removal... 

The replacement of the tosyloxy groups in cellulose tosylate and its derivatives upon interaction with amines leads to the formation of mixed polysaccharides containing units of N-alkyl(aryl)-substituted amino-deoxy sugars. 

A study of the effect of the structure and size of the amine radical (butylamine, dibutylamine, hexylamine, piperidine, aniline) on its reactivity in the nucleophilic replacement of tosyloxy groups in cellulose tosylate has shown (29) that this reactivity depends primarily on the basicity of the amine. TTiis assumption was confirmed by a study of the interaction of cellulose toxylates of different degrees of substitution (DS from 0.3-1.7) wit iminodiacetic and anthranilic acids 30, 31). TTie degree of substitution of the reaction products with respect to the N-carboxyalkyl(aryl)amino groups was found to be lower than that of the corresponding N-alkyl(aryl)araino derivatives. 

Secondary as well as primary tosyloxy groups can be replaced under the conditions adopted for the reaction of nucleophilic substitution, which indicates the high nucleophilicity of sodium acetylide and phenylacetylide. The replacement of the alkyl hydrogen by an aryl radical increases the nucleophilicity of the corresponding metal acetylides this finding is consistent with literature data (61). 

Rules (1) and (3) are extensions of the arguments used by Matheson and Angyal " to explain the behavior of the di-O-tosyl derivatives of the three dianhydrides toward sodium iodide. These authors found that, in the d-mannitol derivative, both tosyloxy groups are readily replaceable by iodine but in the D-glucitol derivative only one, and in the L-iditol derivative neither, tosyloxy group was replaceable. Wiggins and Wood had obtained a parallel series of results from reactions of the di-O-tosyl and di-O-mesyl... 

The tosyloxy groups of tritosyl adenosine were not replaced by iodine on treatment with sodium iodide, showing the absence of a tosyl group at position (5). Hence monotrityl-adenosine is 5-trityl-adenosine, and adenosine must have a furanose structure. 

L-(+)-Tartaric acid was converted to A, the known intermediate used in the synthesis of exo-brevicomin (cf. Figure 4.14). Substitution of the tosyloxy group of A with an Ao-amyl group yielded B, which was finally converted to (7,R,8S)-(- -)-disparlure (85). When the tosyloxy group of A was replaced with an octyl group, C was obtained, and it later gave (7S, 8/ )-(-)-disparlure (85 ). We synthesized 5.2 g of (+)-85 and... 

Base-induced cyclization of a 2-amino- or 2-acetamido-2 -methoxybenzo-phenone gives a good yield of the acridinone but variations in the base used, substituent R, solvent and temperature have a considerable effect on the yield. Replacing the ether by a tosyloxy group improves the yield of 9-acridinone to 91%. 

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