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Structure of N-hydroxyimide of bicyclo[2.2.1]hept-5-en-еndo,еndo-2,3-dicarboxylic acid
Authors: S.V. Kravchenko
Number of views: 528
Some researchers have reported that anhydride of bicycle [2.2.1] hept-5-en-endo, endo-2,3-dicarboxylic acid reacted with mixture of hydroxylamine hydrochloride and sodium methylate yielding 1,4-dioxo-5,8-endomethylene-3,8,9,10-tetrahydrobenz-2,3-oxazine. We think that this is not true. As we have found, anhydride of bicycle [2.2.1]hept-5-en-endo,endo-2,3-dicarboxylic acid reacted with hydroxylamine in the methanol solution yielding only N-hydroxyimide of bicycle[2.2.1]hept-5-en-endo,endo-2,3-dicarboxylic acid. The melting point of recrystallized N-hydroxyimide of bicycle[2.2.1]hept-5-en-endo,endo-2,3-dicarboxylic acid is 163-164 °C. It is close to the earlier reported value of 1,4-dioxo-5,8-endo-methylene-3,8,9,10-tetrahydrobenz-2,3-oxazine which is 160 °C. The structure of N-hydroxyimide of bicycle[2.2.1]hept-5-en-endo,endo-2,3-dicarboxylic acid has been established by means of NMR 1H spectroscopy, mass-spectrometry and finally by XRD study. According to the XRD data, the pyrrolidine ring in N-hydroxyimide of bicycle[2.2.1]hept-5-en-endo,endo-2,3-dicarboxylic acid has the trans orientation to the endo methylene bridge of the norbornane – the С9-С8-С3-С2 torsion angle is equal 151.04(13) degree. The length of the N-O bond is 1.3806(17) Å. The nitrogen atom has planar configuration – the sum of its bond angles is 359.37 degrees.