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THE CHEMISTRY OF ARSINE OXIDES RELATED TO THE SYNTHESIS OF ARSENOSUGARS
Citation:
Fricke, M., H. Sun, N. Gorman, J T. Creed, J. Thayer, J. A. Caruso, AND W. R. Cullen. THE CHEMISTRY OF ARSINE OXIDES RELATED TO THE SYNTHESIS OF ARSENOSUGARS. Presented at International Conference on Environmental and Biological Aspects of Main-Group Organomettalics, Pau, France, December 3-5, 2003.
Impact/Purpose:
The goal is to develop an extraction protocol that mimics the human digestive tract and then to use it to assess the bioavailable fraction of arsenic from complex dietary mixtures such as a daily composite -- to move current methods toward a better human physiologically-based exposure estimate method which approximates the "true" bioavailability of arsenic within an environmental or dietary matrix.
Description:
Ongoing toxicokinetic and biogenesis investigations require gram quantities of the naturally occurring dimethylarsinoylribofuranosides. The principal synthetic route to these compounds involves the hydrogen peroxide oxidation of the parent arsine in ether. This reaction is hazardous; at least one laboratory explosion has occurred involving these conditions.
We wish to report a new route to arsine oxides involving the activation of dimethylarsinic (cacodylic) acid by reaction with carbonyldiimidazole. The resulting dimethylarsinoylimidazolide reacts with Grignard or organolithium reagent to produce arsine oxides. This route approaches arsine oxides through a reduction and avoids the dangerous oxidation reaction. Mass spectroscopic evidence for a mechanism of this reaction will be discussed.
The 19th century Meyer reaction has been examined as a one-step alternate procedure for attaching the dimethylarsinoyl group to sugar substrates. Yields and methods for the Meyer synthesis of trimethylarsine oxide will be reported.
The final point of discussion will be the esterification of the arsine oxide group with pinacol to yield 5-coordinate dioxarsolanes. Arsine oxide protection in this manner permits the chemically orthogonal derivatization of side chains in these molecules. This strategy has considerable potential for preparing a variety of unavailable complex arsenosugars. Protection and deprotection chemistry will be described for model arsine oxides.
This work has been conducted by the United States Environmental Protection Agency. It has been subjected to Agency review and approved for publication. Mention of trade names or commercial products do not constitute endorsement or recommendation for use.