Triacetyl-D-glucal

These key intermediate is accessible from triacetyl-D-glucal 38 in a large-scale adaptable 5-step sequence in an overall yield of 30 % conversion of 38 into hexenoside 39 according to a known two-step procedure (55), tosylation to the chloro-tosylate 40, since the chloride ions formed during the reaction in situ displace the activated allylic tosyloxy function, and, finally, the consecutive reductive removal of tosyloxy- and chloro groups 40 -> 35 (56,57) ... 

In the first attempts at deacetylation of triacetyl-D-glucal, aqueous barium hydroxide was used and an uncrystallizable sirup was obtained2... 

If the mixture of triacetyl-D-glucal dibromides is shaken with silver carbonate or oxide in methanol, the bromine atom at carbon 1 is exchanged for a methoxyl group.3 Here again four isomers are to be expected, which consist of the a. and /3 methyl glycosides of the 2,4,6-triacetyl D-glucose and D-mannose 2-bromohydrins (XI). Two of these methyl triacetyl-2-... 

Chlorine can add to the double bond in triacetyl-D-glucal in a manner similar to that of bromine.311 The resulting dichlorides (XIV) have more tendency to crystallize than the dibromides. However, many of the... 

A tetraacetyl-2-desoxy-2-chloro-D-hexose (XV), which is shown to be homogeneous by its melting point and rotation, can be prepared in good yield from the mixture of triacetyl-D-glucal dichlorides by treatment with silver acetate in glacial acetic acid.3 Likewise, the mixture of... 

The corresponding triacetyl-2-desoxy-2-halogeno-D-hexoses (XVIII) (see page 218) are formed from the triacetyl-D-glucal dihalides by reaction with moist silver carbonate.11 The 2-desoxyaldonic acid (the so-called... 

The oxidation of triacetyl-D-glucal with ozone produced 2,3,5-triacetyl-D-arabinose (XIX),8 which was converted to D-arabinose and the sugar... 

The steric course of the reaction of derivatives of D-glucal that are substituted at the hydroxyl of carbon 3 proceeds in chloroform solution somewhat differently.4-18 For example, triacetyl-D-glucal yielded predominantly l-benzoyl-3,4,6-triacetyl-D-glucose (XXII), which has a... 

Similar results, although with lesser yields, were reported for oxidations with hydrogen peroxide in /erf-butanol in the presence of osmium tetroxide.14 With triacetyl-D-glucal, as well as with free D-glucal, the D-glucose configuration is formed to a greater extent than the D-mannose one. 

The free hydroxyl group of carbon atom 1 of the cyclic tautomeric form can be acetylated. The resulting triacetate (XXV) is different from triacetyl-D-glucal, and it loses the 1-acetyl as a result of boiling with water and is reconverted to diacetyl-D-pseudoglucal.18 (3) The... 

With Dische s reagent for 2-desoxy sugars (diphenylamine in acetic acid and sulfuric acid) triacetyl-D-glucal and a series of other glycals and glycal derivatives give the same or a similar color as the 2-desoxy sugars.25-28... 

Many known addition reactions of sulfur-containing reagents to unsaturated sugar derivatives involve free radical processes. For example, when triacetyl-D-glucal 81 is treated with thio-lacetic acid in the presence of free radical initiators, the mixture of 2-thio-D-mannitol 149 and glucitol 150 is formed (O Scheme 67) [110]. 

In another case (ref.93), triacetyl-D-glucal was used for the preparation of Leukotriene Bj (88). 

Geraniol (-)-Pulegone -Methyl -D-glucoside Triacetyl-D-glucal Arachidonic acid... 

In a synthesis of the CD ring unit of paclitaxel, the cyclohexenone 22 was prepared from triacetyl-D-glucal by a four-step sequence involving Ferrier car-bocycli2jation (sugar carbons indicated), and was then converted as outlined in Scheme 3 into the CD unit 23. ... 

A synthesis of the lactone part (56) of the coenzyme A reductase inhibitor compactin has been reported, starting from compound (57) derived from triacetyl-D-glucal. The chiral intermediate (58), derived also from triacetyl-D-glucal, has been converted to the corresponding lactone and Incorporated ( via C-6 substitution) in a synthesis of the compactin relative (+)-dihydromevinolin. ... 

Zinc catalyzed reductive elimination of acetobromoglucose to give triacetyl D-glucal [64] is the most usual entry into glycal chemistry. Usefully the product can be deprotected under Zemplen conditions and the resulting trihydroxyglucal [65] can be elaborated e.g. fully protected, as its trisilylether by treatment with an excess of r r -butyldimethylsilylchloride and imidazole in DMF [66]. 

For this study, the commercially available triacetyl D-glucal (17) (Table II) was the first substrate subjected to the cycloaddition conditions. Unfortunately, under the conditions used for furanoid glycals, the cycloaddition did not take place. However, when the reaction was carried out at 90 C a 3/2 diastereomeric mixture of adducts 27 was obtained in low yield. Since dihydropyran was found to be a good substrate in the cycloaddition reaction under irradiation, this suggested that the low reactivity of triacetyl D-glucal was due to the acetoxy groups on the ring. 

Pyranoid analogues 148 (B = U, T) of d4 systems have been prepared by standard procedures, as have the related 3 -enes. The same group have also reported 5-aminouiacil nucleosides of type 149, the base-sugar link being made by Ferrier-type condensation with triacetyl-D-glucal. Some a-nucleosides similar to 149, with various bases, have been made by Pd -catalysed condensation of the base with phenyl i,5-di-0-hcnzy -a-T>-erythro-Yiex.-2-enopyranoside. ... 

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