Susana Rojas-Lima, José Norberto Farfán García, Rosa Luisa Santillán Baca, María Dolores Castillo, Martha Elena Sosa-Torres, Herbert Höpfl. "Comparative Structural Characterization of the biquaternized N-CH3 and N-BH3 Derivatives of the cis-Cyclen and cis-Cyclam Condensation Products with Glyoxal". Tetrahedron, 56, 6427-6433 (2000). DOI: http://dx.doi.org/10.1016/S0040-4020(00)00614-1
The biquaternized N-CH3 and N-BH3 derivatives of the cis-cyclen (1,4,7,10-tetraazacyclododecane) and cis-cyclam (1,4,8,11-tetraazacyclotetradecane) condensation products with glyoxal have been prepared and structurally characterized by NMR spectroscopy and in the case of the BH3 adducts additionally by X-ray crystallography. A comparison of the structural data between the four compounds and the starting materials permitted: (i) to establish their overall conformation, (ii) to discuss the structural modifications caused by the N-CH3 and N-BH3 functional groups and (iii) to understand, why the bialkylated tetraazapolycycles can be reduced to the cross-bridged tetraazamacrocycles, in contrast to the borane adducts.