A tetraacetyl

Das a( )-Tetraacetyl-glucosaminyl-chlorid (XV, Schmp. 125 bis 126°) erhielten B. R. Baker und Mitarbeiter (9) aus Pentaacetylglucosamin (VI) mit chlorwasserstoffgesattigtem Ather unter Zusatz von Acet-anhydrid, oder mit Titantetrachlorid in siedendem Chloroform, jeweils in guten Ausbeuten. Uber seine Verwendung zu Synthesen vgl. S.842. 

A tetraacetylation with cleavage of the N—N hond can take place as observed for 3,6-diphenylpyridazine(Scheme 147)... 

Stoodley developed an asymmetric synthesis of (5A)-2,3,4,5-tetrahydropyridazine-3-carboxylic acid (see Section 8.01.6.4). The ring construction was achieved via cycloaddition of dienes 295 bearing a tetraacetyl /3-D-glucopyranosyl moiety for chiral induction with azodicarboxylates (Equation 73) <1999J(P1)2591>. 

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... 

Unlike the other streptobiosamine derivatives (Table IV, page 383) streptobiosamic acid monolactone formed a pentaacetyl derivative " rather than a tetraacetyl compound. Also, acetylation of streptosonic acid monolactone yielded a diacetyl derivative. It was pointed out that either the ordinarily resistant tertiary hydroxyl group had been acetylated in these compounds (XXVII) or that the lactone ring had shifted from the 7- to the /3-position, during the acetylation, with the introduction of an acetyl group at carbon atom four (XXVIII). Whatever the positions of the ester groupings in pentaacetylstreptobiosamic... 

Earlier work established the correct molecular formula of ipecoside as C27H35NO12 mp 175° [ —185° (MeOH) and showed that it contains two phenolic o-dihydroxy groups. On methylation with diazomethane, ipecoside gave 0,0-dimethylipecoside (3 or 4). On treatment with acetyl chloride, the former afforded a hexaacetate, whereas the latter furnished a tetraacetyl derivative (11). 

Early studies (Birch et al., 1958) of the biosynthesis of penicillic acid in P. cyclopium with [2-acetate have postulated the intermediacy of orsellinic acid (17). Orsellinic acid is the classic example of an aromatic compound produced by the polyketide pathway. Indeed, it is formed by aldol condensation of a tetraacetyl unit with no further modifications (Fig. 19). 

Although the Koenigs-Knorr reaction appears to involve a simple backside S 2 displacement of bromide ion by alkoxide ion, the situation is actually more complex. Both a and /3 anomers of tetraacetyl-o-glucopyranosyl bromide give the same /3-glycoside product, implying that they react by a common pathway. 

V sol in ethanol v si sol in acet acid. Prepn is by prolonged heating of tannin with a 5% aq sulfuric acid soln. It is also a coprod of the hydrogenation of tetraacetyl-2-oxy-glucal (Ger) with a Pd catalyst followed by saponification with Ba hydroxide... 

Note. In carbohydrate nomenclature, substitution at a heteroatom is normally indicated by citing the locant of the attached carbon atom, followed by a hyphen, and then the italicized heteroatom element symbol, e.g. 2-0-methyl, 5-N-acetyl. Substituents on the same kind of heteroatom are grouped (e.g. 2,3,4-tri-0-methy 1), and substituents of the same kind are cited in alphabetical order of heteroatoms (e.g. 5-N-acetyl-4,8,9-tri-0-acetyl). The alternative format with superscript numerical locants (e.g, N5,(/,(), ( -tetraacetyl), used in some other areas of natural product chemistry, is unusual in carbohydrate names. 

The only oral complex in clinical use is auranofin 92 (Ridaura), containing tetraacetyl-j8-D-thioglucose and triethyl phosphine ligands. Auranofin is a lipophilic complex, a monomer containing linear two-coordinate Au(I). 

Zervas48 through the catalytic reduction of 2,3,4,6-tetraacetyl-2-hydroxy-D-glucal, has recently been prepared by the reductive desulfurization of ethyl tetraacetyl-l-thio-/ -D-mannopyranoside (XL),47 a substance which has been obtained through the mercaptolysis of mannosidostreptomycin48 and may be prepared through the prolonged action of ethyl mercaptan and hydrochloric acid on D-mannose. 

Not only chiral separations have been achieved with Mi-stationary phases. It has also been demonstrated that the MIP could distinguish between ortho- and para-isomers of carbohydrate derivatives. For example, a polymer imprinted with o-aminophenyl tetraacetyl P-D-galactoside was used to analyze a mixture of p-and o-aminophenyl tetraacetyl P-D-galactoside. As expected, the imprinted ortho analyte eluted after the non-imprinted para component see Fig. 5. Although baseline separation was not obtained, a separation factor of a = 1.51 was observed [19]. 

Fig. 5. Separation of (1) para- and (2) ortho-aminophenyl tetraacetyl 3-D-galactoside, using a polymer imprinted with o-aminophenyl tetraacetyl p-galactoside. Reprinted with permission from Nilsson KGI, Sakguchi K, Gemeiner P, Mosbach, K (1995) J Chromatogr 707 199. Copyright 1995 Elsevier Science...

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