We are chemically combining aldoses with nitrogenous bases to determine by single-crystal X-ray diffraction whether the derivatives formed are either open-chain Schiff bases or cyclic glycosylamines. Previous work in our laboratory has shown that D-mannose tends to yield glycosylamines upon reaction with substituted anilines but Schiff bases upon reaction with substituted phenylhydrazines, which differ from the anilines by only a single N-H moiety; we are now extending this investigation to other aldoses. Concurrently we are using these carbohydrate derivatives as a context in which to investigate the possible role of close intermolecular fluorine…hydrogen interactions in defining their crystal structures. Our previous work has shown that the 3-fluorophenylmannopyranosylamine and the 4-fluorophenylmannopyranosylamine are isomorphous (exhibiting the same solid-state molecular packing arrangement) while the 2-fluorophenylmannopyranosylamine assumes a different molecular packing arrangement, one isomorphous with the non-halogenated N-phenylmannopyranosylamine. A characteristic fluorine…hydrogen interaction is conserved in the isomorphous 3-fluoro and 4-fluoro compounds. To examine such interactions further, we have now synthesized and determined the crystal structure of the 2-fluorophenylhydrazone of D-mannose. In this Schiff base structure the fluorine atom interacts with neighboring C-H groups but not with neighboring O-H groups. Future work will include determination of the crystal structures of the 3-fluoro and 4-fluoro analogues.

Solid-state studies of derivatives formed by reaction of nitrogenous bases with aldoses: Crystal structure of the 2-fluorophenylhydrazone of D-mannose

2019 Spring National Meeting

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