35392-33-7Relevant academic research and scientific papers
Formation of cycloadducts with trans-configurated ester groups from nitrones and dimethyl maleate
Aurich, Hans Guenter,Frenzen, Gerlinde,Rohr, Markus G.
, p. 7417 - 7434 (2007/10/02)
In the 1,3-dipolar cycloaddition of the cyclic nitrone 1c and the acyclic nitrones 8a-h, 12a, b with dimethyl maleate in refluxing chloroform not only the expected cycloadducts with cis-configuration of the two ester groups were formed but also such with trans-configuration. This phenomenon is not limited to chloroform, but was also observed in polar solvents as cyclohexane and n-hexane. However, there is no clue for either a non-concerted reaction course or a subsequent conversion of the cis-products to trans-product, in general. Rather, conversion of dimethyl maleate to dimethyl fumarate seems to be responsible for the formation of the trans-substituted cycloadducts. This conversion can be induced by small quantities of N-alkylhydroxylamine formed from slight decomposition of nitrones under the reaction conditions, or by small quantities of nitrone derivatives possessing a NOH moiety such as N-hydroxy enamine tautomers or nitrone dimers.
