Sequence control in polymer chemistry through the Passerini three-component reaction.

A new strategy to achieve sequence control in polymer chemistry based on the iterative application of the versatile Passerini three-component reaction (P-3CR) in combination with efficient thiol-ene addition reactions is introduced. First, stearic acid was used as a starting substrate to build up a sequence-defined tetramer with a molecular weight of 1.6 kDa. Using an acid-functionalized PEG allowed for an easier isolation of the sequence-defined macromolecules by simple precipitation and led to a sequence-defined pentamer in a block-copolymer architecture. Importantly, this new strategy completely avoids protecting group chemistry. By following this strategy, a different side chain can be introduced to the polymer/oligomer backbone in a simple way and at a defined position within the macromolecule.