Oligomers by consecutive in situ Michael-additions

Article abstract of DOI:10.1002/ardp.19943270707

Under the conditions of a Mannich reaction the expected aminomethyl products of 2- and 4-pyridylacetonitriles and -esters could not be isolated; spontaneous amine elimination and subsequent polyaddition yield oligomers. From 2-pyridylacetonitrile a homogenous atactic oligomer is obtained; its microtacticity is elucidated by NMR spectroscopy. 4-Pyridylacetonitrile reacts similarly leading to a mixture of substances with a broad molecular mass distribution. The corresponding pyridylesters react more slowly and allow the isolation of monomeric acrylic esters together with oligomers, the configurations of which were determined. 3-Pyridyl compounds show a reduced reactivity leading primarily to the monomers. MNDO calculations indicate that 2- and 4-pyridyl derivatives react via mesomerically stabilized push pull forms, the 3-pyridyl compounds via zwitter ions.