Methylation with Diazomethane–Boron Trifluoride Etherate

Deferrari, Jorge O.; Gros, Eduardo G.; Thiel, Inge M.E.

doi:10.1016/b978-0-12-746206-6.50072-2

Cited by 11 publications

(5 citation statements)

References 6 publications

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“…In the initial work on the acylated oligosaccharides of M. kansasii, we had not attempted to pinpoint the position of the 2,4-dimethyltetradecanoyl residues. Since then, we have developed the requisite methodology.2 The diazomethane-boron trifluoride etherate methylation procedure (Deferrari et al, 1972), methylation with methyl trifluoromethanesulfonate (Arnarp et al, 1975), and a procedure involving acyl location through use of 1 -methoxyethyl protecting groups (Gray, 1976) had all suffered in our hands from the problem of under O-methylation. Modification of Arnarp's procedure, using trimethyl phosphate as a solvent, proved to be highly suitable for present purposes.…”

Section: Discussionmentioning

confidence: 99%

Trehalose-containing lipooligosaccharide antigens of Mycobacterium sp.: presence of a mono-O-methyltri-O-acyltrehalose "core"

Hunter¹,

Barr²,

McNeil³

et al. 1988

Biochemistry

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We have described the surface antigens of Mycobacterium kansasii as trehalose-containing lipooligosaccharides (LOS) which at the nonreducing "epitope" end bear a unique amino sugar containing diglycosyl unit, whereas the putative reducing end consists of an acylated alpha, alpha-trehalose-containing tetraglucosyl "core" [Hunter, S. W., Jardine, I., Yanagihara, D. L., & Brennan, P. J. (1985) Biochemistry 24, 2798-2805]. The presence of a new variation on this core, in Mycobacterium szulgai, is now reported, ----3)beta-D-Glcp-(1----6)alpha-D-Glcp(1----1)3,4,6-tri-O-acyl-2-O- Me-alpha-D-Glcp, representing the first example of an O-methyltrehalose unit in nature. The simplest of the LOS class of glycolipids in M. szulgai was defined as alpha-L-2-O-Me-Fucp(1----3)alpha-L-Rhap(1----3)alpha-L-Rh ap(1----3) beta-D-Glcp(1----6)alpha-D-Glcp(1----1)3,4,6-tri-O-acyl-2-O-Me-alpha-D-G lcp. Further glycosylation of this nonantigen, by an incompletely defined 6-deoxyhexosyl residue, confers specific antigenicity on the organism. Thus, these extraordinary structures, in a manner analogous to the better known lipopolysaccharides from rough variants of Enterobactericiae, are highly amphipathic and display variability not only in the immunogenic, distal region but also in the "invariant" lipophilic core. The contribution of these glycolipids to the hydrophobic barrier, the pseudo outer membrane of mycobacteria, is discussed.

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Section: Discussionmentioning

confidence: 99%

Trehalose-containing lipooligosaccharide antigens of Mycobacterium sp.: presence of a mono-O-methyltri-O-acyltrehalose "core"

Hunter¹,

Barr²,

McNeil³

et al. 1988

Biochemistry

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“…A freshly prepared solution of diazomethane 23 was added dropwise at 0 • C to a solution of 24 (80 mg, 0.7 mmol) in CH 2 Cl 2 (3 mL) in the presence of BF 3 .OEt 2 (3 mL, 0.21 mmol) until the yellow colour persisted. The reaction mixture was stirred at 0 • C until TLC showed complete consumption of starting material and was then allowed to reach room temperature.…”

Section: N-benzyloxycarbonylaminoethyl 4-azido-3-o-benzoyl-46dideoxy-...mentioning

confidence: 99%

Sensitive and specific enzyme immunoassays for antigenic trisaccharide from Bacillus anthracis spores

et al. 2009

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A straightforward synthesis of an anthrose-containing trisaccharide derived from Bacillus anthracis was achieved. Antibodies raised against this hapten provide a highly sensitive enzyme immunoassay with a detection limit of 8.5 pmol mL(-1). By investigating the specificity of the antibodies obtained using different mono-, di- and trisaccharide synthetic analogues, we demonstrated that the epitope was mainly made up of the methyl group at C-5, the butamido group at C-4 and the hydroxyl at C-3 of the anthrose unit, the other parts of the trisaccharide appearing little involved in the recognition.

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“…Initial efforts to locate the positions of the acyl functions employed the diazomethane-boron trifluoride etherate procedure of Deferrari et al (11), the methyl vinyl ether method of Gray (17), and the methyl trifluoromethanesulfonate procedure of Arnarp et al (1). These techniques, as a whole, were deemed unsatisfactory due to the generation of heterogeneous products apparently arising from under 0-alkylation or partial deacylation.…”

Section: Methodsmentioning

confidence: 99%

Location of acyl groups of trehalose-containing lipooligosaccharides of mycobacteria

et al. 1987

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A variant of a Mycobacterium sp. originating in a patient with Crohn's disease, but not necessarily implicated in the disease, provided a simple version of a newer class of species-specific surface glycolipids, the trehalose-containing lipooligosaccharides. A combination of high-resolution 1H nuclear magnetic resonance, methylation, ethylation, and absolute configurational analysis established the structure of the oligosaccharide unit as beta-D-Glcp(1----3)-alpha-L-Rhap(1----3)-alpha-D-Glcp(1----1)-alph a-D-Glcp (where Glc is glucose, Rha is rhamnose, and p is pyranosyl), and gas chromatography-electron impact mass spectrometry allowed identification of the fatty acyl esters as primarily 2,4-dimethyltetradecanoate. The relative simplicity of the glycolipid combined with the application of a mild methylation procedure and californium-252 plasma desorption mass spectrometry allowed recognition of three such acyl residues on the 3-, 4-, and 6-hydroxyl positions of the terminal glucosyl residue of the trehalose unit. Thus, the glycolipid is decidedly amphipathic yet is clearly not membranous. This observation leads to speculation about the role of these novel lipooligosaccharides in contributing to the outer segment of the hydrophobic barrier of the cell wall of certain mycobacteria.

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Methylation with Diazomethane–Boron Trifluoride Etherate

Cited by 11 publications

References 6 publications

Trehalose-containing lipooligosaccharide antigens of Mycobacterium sp.: presence of a mono-O-methyltri-O-acyltrehalose "core"

Trehalose-containing lipooligosaccharide antigens of Mycobacterium sp.: presence of a mono-O-methyltri-O-acyltrehalose "core"

Sensitive and specific enzyme immunoassays for antigenic trisaccharide from Bacillus anthracis spores

Location of acyl groups of trehalose-containing lipooligosaccharides of mycobacteria

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