40597-52-2Relevant articles and documents
Disproportionation reactions from glyoxal and difunctional basic molecules
Chassonnery, Dominique,Chastrette, Francine,Chastrette, Maurice,Blanc, Alain,Mattioda, Georges
, p. 188 - 199 (2007/10/02)
Glyoxal was reacted with basic difunctional molecules in order to study the disproportionation reaction.Symmetrical and unsymmetrical 1,2-diamines gave rise to piperazinones; their 1,3-diamine analogues yielded hexahydrodiazepinones; and β-aminoalcohols yielded morpholinones and hydroxyamino acids.Aminoamides gave the expected piperazinediones in low yields and no reaction was observed with diamides.The first step of the reaction consists of the formation of dihydroxy compounds, from which the more basic function assists the departure of OH, providing the expected more stable iminium ion.The observed regioselectivity is consistent with the relative basicities of the two functions; a 100percent regioselectivity is observed with aminoalcohols (giving way to morpholinones and not to amides), a good regiposelectivity with most of N-alkyl-N'-aryl-diamines and a rather low one with N-methyl-N'-ethyl- or N-methyl-N'-p-methoxyphenyl-diamines.Geometry factors were related to the better yield obtained with 1,2-diamines compared with 1,3-diamines.The mechanism was investigated.When deutared glyoxal and diamines were reacted in D2O, incorporation of deuterium was observed, in accordance with the formation of an enolate in the course of the oxidoreduction.The low reactivity of aminoamides and the observed regioselectivities could be related to both the weak basicity of the function that is supposed to allow the formation of the iminium ion and the basicity of the other function that accepts a positive charge and which, if too weak, impedes the reaction because of the instability of the intermediate iminium ion. glyoxal / disproportionation rules / basic difunctional molecules
