1. Lanthanum-catalyzed aqueous acylation of monosaccharides by benzoyl methyl phosphate (1)
- Author
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Gray, Ian James, Ren, Rui, Westermann, Bernhard, and Kluger, Ronald
- Subjects
Nuclear magnetic resonance -- Usage -- Chemical properties -- Research ,Sugars -- Research -- Usage -- Chemical properties ,Lanthanum -- Chemical properties -- Usage ,Monosaccharides -- Research -- Usage -- Chemical properties ,Chemistry ,Chemical properties ,Usage ,Research - Abstract
It was previously reported that diols dissolved in water (pH 8, EPPS buffer) react with benzoyl methyl phosphate (BMP) in the presence of lanthanide ions to form monobenzoyl esters. We have investigated the possibility of extending this process to include formation of esters of monosaccharides in water from lanthanide-catalyzed reactions with BMP. The combination of methyl-α-D-glucopyranoside and BMP in the presence of lanthanum trichloride gave selective monoacylation of the 2- and 6-hydroxyl groups in a ratio of 2:1. The likely mechanism involves preferential bisbidentate coordination of BMP and the diol to lanthanide ion (which explains how an ester forms when water is in enormous excess) followed by base-catalyzed intramolecular acyl transfer. The method should be generally applicable where a selective acylation reaction in water as solvent is desirable. Key words: benzoyl methyl phosphate, lanthanide, catalysis, water, monoacylation, selective. Il a ete rapporte anterieurement que les diols dissous dans l'eau (pli de 8 et tampon << EPPS >>) reagissent avec le phosphate de benzoyle et de methyle (PBM), en presence d'ions de lanthanide, pour conduire a la formation d'esters monobenzoyles. On a examine la possibilite d'etendre cette methode de facon a inclure la formation d'esters de monosaccharides, par des reactions en milieu aqueux avec du PBM et catalysees par des lanthanides. La combinaison de l'α-D-glucopyranoside de methyle et du PBM, en presence de trichlorure de lanthane, conduit a la monoacetylation selective des groupes hydroxyles en positions 2 et 6, dans un rapport de 2 : 1. Le mecanisme probable implique la coordination bisbidentate preferentielle du PBM et du diol a l'ion lanthanide (qui explique comme un ester peut se former en presence d'un enorme exces d'eau), qui est suivie d'un transfert de groupe acyle intramoleculaire catalyse par la base. La methode devrait etre applicable d'une facon generale quand il est desirable d'effectuer une reaction d'acetylation selective en utilisant l'eau comme solvant. Mots cles : phosphate de benzoyle et de methyle, lanthanide, catalyse, eau, monoacetylation, selective. [Traduit par la Redaction], Introduction We are reporting our work in conjunction with the production of an issue of the Canadian Journal of Chemistry honoring Walter Szarek, whose work in the field of biological [...]
- Published
- 2006