Addition of Nitromethane to Aldoses. – A Comprehensive Study of the Diastereoselectivity of the Fischer‐Sowden Reaction by the Help of 13C‐NMR Spectroscopy1) The addition of nitromethane to aldoses, commonly referred to as „Fischer‐Sowden reaction”︁, is not as stereoselective as can be concluded from the literature. This is the outcome of a comprehensive study which covered besides glyceraldehyde all aldotetroses, ‐pentoses and ‐hexoses. The ratio of the pair of diastereomeric nitroalditols has been determined in each case by 13C‐NMR spectroscopy. Thus, incidentially, a whole set of spectral data for all tetritols, pentitols, hexitols and heptitols with a terminal nitro group has been obtained, which can be correlated systematically to the respective data for the parent alditols. From these results follows that at least under conditions which give high yields of products, the reaction is thermodynamically controlled; thus, the product ratio is determined by the different energy content of the product nitroalditols (or their nitronates), which is a result of different patterns of steric interactions between substituents.

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The 1H‐NMR spectra of all diastereomeric alditols with a terminal nitro group up to a chain length of seven carbon atoms (31 compounds) have been recorded at 500 MHz in D2O. In most cases, a complete first‐order analysis has been performed. The spectra show systematic correlations with those of the parent alditols. Despite a special situation around the nitromethyl group no severe deviations of preferred conformations in solution from those of the parent alditols have been observed.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.