Dual side chain control in the synthesis of novel sequence-defined oligomers through the Ugi four-component reaction†
The synthesis of sequence-defined oligomers by the iterative application of the modular Ugi four-component reaction (U-4CR) and the efficient thiol–ene addition reaction is described. By varying the amine component in the U-4CR, a sequence-defined and monodisperse tetramer (M = 1568.5 g mol−1) was obtained. More interestingly, if both the amine and the isocyanide components were varied simultaneously in the U-4CR, a double sequence-controlled, monodisperse pentamer (M = 2411.8 g mol−1) bearing ten different and selectable side chains was obtained. All oligomers were thoroughly characterized by NMR and IR spectroscopy, mass spectrometry and GPC.