D-Glucal triacetate

Unsaturated sugars are useful synthetic intermediates (11). The most commonly used are the so-called glycals (1,5- or 1,4-anhydroalditol-l-enes). In the presence of a Lewis-acid catalyst, 3,4,6-tri-0-acetyl-l,5-anhydro-2-deoxy-D-arabinohex-l-enitol [2873-29-2] commonly called D-glucal triacetate, adds nucleophiles in both kineticaHy controlled and thermodynamically controlled (soft bases predominately at C-3 and hard bases primarily at C-1) reactions (11,13). 

Previously, the reaction of 3,4,6-tri-0-acetyl-l,5-anhydro-2-deoxy-D-arabino-hex-l-enitol (D-glucal triacetate) (20) with lead thiocyanate in a mixture of acetic acid, acetic anhydride, and carbon tetrachloride had been reported by Igarashi and Honma.37 They observed formation of isothiocyanate 21 as the main product, accompanied by a mixture of four isomeric thiocyanates. 

On the other hand, methanolysis of 277 in the presence of silver carbonate and silver perchlorate gave the corresponding glycoside 278 in 83% yield, as well as the 2-thiocyanato-D-glucal triacetate 276 in 11% yield. Desulfurization of 278 with Raney nickel afforded 3,4,6-tri-O-acetyl-2-deoxy-0-D-arabino-hexopyranoside (279) in 56% yield.37... 

Several reactions were carried out with chiral olefines. For example, only one stereoisomer ii was isolated from the Patemo-Btichi reaction of D-glucal triacetate 10 with acetone (Scheme 3) [9]. 

A method using silver(I) fluoride and chlorine is sufficiently mild for the isolation of the chlorine fluoride adducts in good yield, whereas the combination of IV-chlorosuccinimide and hydrogen fluoride gives no fluorinated products. The reaction of chlorine with a suspension of D-glucal triacetate and silver(I) fluoride in an acetonitrile/benzene solution is unusual in that it gives all four possible 3,4,6-tri-0-acetyl-2-chloro-2-deoxy-D-glycopyranosyl fluorides... 

D-Glucal triacetate (1.36g, 5 nmiol) in dry MeCN (ca. 25 mL) was stirred vigorously with powdered AgF (4 g, 32 mmol). A solution of 10% Bi in benzene (w/ v, 0.85 g) was then added dropwise. After completion of the Brj addition (ca. 10 min), the solution was stirred for a further 20 min and then filtered from the copious precipitate of silver halide. To this solution was added sat. brine, the precipitated AgCI was removed, the filtrate was concentrated to ca. 10 mL and CHClj (30 niL) was added. The CHCI3 solution was extracted successively with aq NajSjOj, aq NaHCO, and H2O. After drying (Na SO j), evaporation produced a... 

Takiura, K, Honda, S, Hydroxy- and acetoxy-mercuration of D-glucal triacetate, Carbohydr. Res., 23, 369-377, 1972. 

The recent interest " in unsaturated carbohydrates has been both stimulated and furthered by advantageous application of n.m.r. The studies of shkimic acid and of D-glucal triacetate that showed that these compounds adopt a half-chair conformation also demonstrated the potentiality of n.m.r. in the study of unsaturated carbohydrates. It has now been shown that stereodependent long-range coupling effects associated with the double bond enhance the structural information n.m.r. provides. 

Glycals are suitable precursors for 1,2-trans phenylselenyl azides, and in 1994 two different preparative approaches were reported.3,4,6-Tri-(9-benzyl-2-deoxy-2-(phenylseleno)-(3-D-glucopyranosyl azide (176) and the a-o-mannopyran-osyl azide (177) were prepared by two different methods trimethylsilyl azide + A -phenylselenophthalimide + tetrabutylammonium fluoride in dichloro-methane at room temperature, or sodium azide + phenylselenyl chloride in A, A -dimethylformamide. The physical data of these compounds differ considerably between the two reports and so the results remain somewhat dubious. When D-glucal triacetate 140a was treated with (diacetoxyiodo)benzene and sodium azide in the presence of diphenyl diselenide at room temperature, an... 

Corey synthesis commenced from D-glucal triacetate 17, which was converted into the epoxide 19 via 18 (summarized in Scheme 2). Conformation of the pyranose ring was analyzed to be axial C -OMe, equatorial C, so that opening... 

D-glucopyranosyl donor, and subsequent displacement of a 2-triflate with azide ion. The crystalhne methyl 3-azido-2,3-dideoxy-a-D-glucopyranoside has been synthesized from D-glucal triacetate by hydration, Michael addition of azide, methanolysis, chromatographic fractionation and deacetylation. ... 

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