3 heptaacetate

Acetylation of Kasuganobiosamine (4). Acetic anhydride (2 ml.) and pyridine (4 ml.) were added to kasuganobiosamine (212 mg., 0.688 mmole) and the solution was allowed to stand at room temperature for 24 hours. The reaction mixture was treated with ice-water and extracted three times with chloroform. The organic layer was dried over sodium sulfate. After removal of the solvent, an oily material was treated with 30 ml. of ether to deposit a crystalline material. It was further recrystallized from ether-ethyl alcohol to afford a needle crystalline material (409 mg., 0.679 mmole), m.p. 242°-243°C., and identified to be heptaacetate of 4. Anal Calcd. for C26H38014N2 C, 51.58 H, 6.44 O, 36.69 N, 4.41. Found C, 51.27 H, 6.44 O, 36.42 N, 4.53. 

Glycosides may also be prepared by enzyme-catalyzed condensation reactions utilizing a glycosyl fluoride. Thus 6-0-a-maltosylcyclodextrins were prepared enzymically from a-maltosyl fluoride (obtained from the corresponding heptaacetate by Zemplen deacetylation) and cyclodex-trins. " ... 

A remarkable inertness towards acylation is shown by the secondary hydroxyl group on C-3 in maltose, lactose, and their methyl j8-glycosides. Benzoylation of maltose with 10 molar equivalents of the acid chloride in pyridine gave122 the octabenzoate and the l,2,6,2, 3, 4, 6 -hepta-0-benzoyl derivative in the ratio of 5 6, and treatment of /3-maltose monohydrate with 8.8 molar equivalents of acetyl chloride in pyridine-toluene at 0° gave123 the 1,2,6,2, 3, 4, 6 -heptaacetate and the octaacetate in the ratio of 27 10. Under similar conditions of benzoylation, cellobiose was converted into its oc-... 

The derivative 90 was obtained by condensation of the purpurin-18-A-hexylimide-17-propionic acid with aminolactose heptaacetate in the presence of benzotriazol-l-yloxy-tris(dimethylamino)phosphonium hexafluorophosphate (BOP) followed by the deacetylation procedure. The lactose-photosensitiser conjugate linked by an ethylene moiety was also prepared by following a similar approach. The purpurin-18-methyl ester 81 was converted into /V-(3-iodobenzyl)/ /evo-purpurin-18-7V-hexylimide-17-propionic ester by hydrogenation over Pd/C followed by reaction with 3-iodo-benzylamine. Afterwards, the propargyllactose heptaacetate reacted with A-(3-iodobenzyl)rMeio-purpurin-18-A-hexylimide-l 7-propionic ester in the presence of tris(dibenzylidieneacetone)dipalladium(0) (Pd2-dba3) which, after deacetylation conditions, afforded the derivative 89 (Fig. 9).68... 

Phenyl l-thio-/S-cellobioside heptaacetate to 1,5-anhydro-4- (d-D-gluco-pyranosyl)-D-glucitol heptaacetate... 

SCHEME 9. Durette, Hough, and Richardson s synthesis of methyl 3-bromo-3-deoxy-p-maltoside via opening of the 2,3-allo-epoxide derived from the l,2,2, 3, 4, 6,6 -heptaacetate of methyl p-maltopyranoside (1974). 

Treatment of the dichloromethyl derivative 472 with sodium cyanide gave290 an almost quantitative yield of the epimeric nitriles (480, 481). The mixture could not he separated by chromatographic methods, but differences in reactivity of the stereoisomers towards methanolic hydrogen chloride allowed isolation of only one ester, namely, 482 the trails cyanide underwent ready conversion into the methyl ester, whereas the cis compound gave a rather complicated mixture of products, with amide 483 being identified as the major component. Reduction of the ester group in 482, followed hydrolysis of the dichloromethyl group, afforded DL-t/ireo-DL- Y/o-octose, characterized as the heptaacetate, and identified as threo-ido-octito by comparison with an authentic sample. 

Attempts have been made to solve the problem of selective substitution in sucrose octaacetate. Adsorption of the latter onto alumina for 46 hours gave a complex mixture from which, after extensive chromatography, were isolated the 2,3,4,6,l, 3, 4 -heptaacetate in 9% yield,11 the 2,3,6,l, 3, 4, 6 -heptaacetate in 2.7% yield,117 and the 2,3,4,6,1, 3, 6 -heptaacetate in 6% yield.117 Although selective deacylation of the octaacetate apparently occurs at secondary positions, as well as at 0-6, it is likely that heptaacetates containing 4- and 4 -OH groups... 

Acetates and benzoates are widely used as characteristic derivatives of carbohydrates, and for the assay and protection of hydroxyl groups. Various maltose heptaacetates having a free hydroxyl group on C-l, C-2, C-3, C-6, or C-6 have been synthesized. 2,3,6,2, 3, 4, 6 -Hepta-0-acetyl-/3-maltose (17) has been prepared by hydrolysis of the corresponding glycosyl halide.57,58 The reaction conditions may not always result in the isolation of the anomerically unsubstituted acetate, as was shown by Corbett and coworkers,59 who obtained three... 

On treatment with aqueous potassium hydroxide for 40 h on a steam bath,32 phenyl /3-maltose heptaacetate (40) was converted into the 1,6-anhydride 41, isolated in 72% yield as its acetate (42). Compound 42... 

Comparison of the -n.m.r. spectrum of 3-0-(methylsulfonyl)-/3-maltose heptaacetate (31) with that of /3-maltose octaacetate showed only one divergence, —0.34 p.p.m. upfield of the H-3 resonance, indicative of the location of the methylsulfonyloxy group on C-3. A similar comparison of H-n.m.r.-spectral parameters as between methyl 4 -0-(methylsulfonyl)-/3-maltoside hexaacetate and methyl /3-maltoside heptaacetate revealed that the methylsulfonyloxy group in the former compound is located on C-4, as the H-4 resonance appeared —0.3 p.p.m. to higher field than the H-4 resonance for the heptaacetate.66 In the H-n.m.r. spectrum of methyl 3-azido-3-deoxy-/3-maltoside heptaacetate, the H-3 resonance appeared at 1.70 p.p.m. to higher field of... 

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