14199-83-8Relevant articles and documents
Extension of chains of 1-deoxy-1-nitroalditols by nitrile oxide cycloaddition. Synthesis of 4-N-substituted 3,4-didesoxy-2-ulosonic acids
Mack, Hans,Brossmer, Reinhard
, p. 4539 - 4560 (1998)
Treatment of protected nitroalditols 1a or 2 with silylenolpyruvate (3) or methyl acrylate leads via nitrile oxide cycloadditon to cyclo-tautomers of oximes, 5 or 4, respectively 4,5-dihydro-isoxazole 6. N-Acetyl-4-deoxy-4- (E/Z)-hydroxyimino-neuraminic acid (7) is obtained by deprotection of 4. Hydrogenation of 7 yields N-acetyl-4-amino-4-deoxy-neuraminic acid (9) and pentahydroxy-nononic acids 12a,b. The synthesis is useful for the chain extension of protected nitroalditols 13a and 20a, to give the corresponding oximes 15 and 22. This work provides a general method for the extension of sugar chains by three C-atoms and thus a novel synthesis of α-keto acids containing an oxime and amino function.
Addition of Nitromethane to Aldoses. - A Comprehensive Study of the Diastereoselectivity of the Fischer-Sowden Reaction by Help of 13C-NMR Spectroscopy
Koell, Peter,Stenns, Claudia,Seelhorst, Willi,Brandenburg, Heinz
, p. 201 - 206 (2007/10/02)
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.