No abstract

Sequence-defined polymers show promise for biomimetics, self-assembly, catalysis, and information storage, wherein the primary structure begets complex chemical processes. Here we report the solution-phase and the high-yielding solid-phase syntheses of discrete oligourethanes and methods for their self-immolative sequencing, resulting in rapid and robust characterization of this class of oligomers and polymers, without the use of MS/MS. Crucial to the sequencing is the inherent reactivity of the terminal alcohol to "unzip" the oligomers, in a controlled and iterative fashion, releasing each monomer as a 2-oxazolidinone. By monitoring the self-immolation reaction via LC/MS, an applied algorithm rapidly produces the sequence of the oligourethane. Not only does this process provide characterization of structurally complex molecules, it works as a reader of molecular information.Sequence-defined polymers, e.g., β-peptides, γ-peptides, peptoids, polyureas, and polycarbamates, 1 have garnered significant interest over recent decades, to the point that their size and structural complexity are nearing those of biopolymers. 2 This complexity renders sequence elucidation difficult, at times -impossible. When successful, analysis has relied upon an assortment of 1 and 2D NMR spectroscopy together with sophisticated mass spectrometry techniques. 3 Molecular sequencing techniques such as Edman degradation for peptides and Sanger sequencing for DNA are among the most significant chemical achievements of the 20th century. Modern proteomic studies rely on comparisons to databases for protein identification, 4 wherein many of the protein sequences were elucidated via Edman degradations. Notably, very few techniques analogous to Edman or Sanger sequencing exist for synthetic macromolecules, likely due to the fact that only recently has synthetic methodology been capable of creating monodisperse macromolecules as structurally complex as biopolymers. 1 Peptoids are one exception, with Zuckerman realizing their stepwise chemical degradation on resin. 5 As more examples of sequence-defined

3-ethyl-6-vinyltetrahydro-2H-pyran-2-one (EVP) is a CO2-derived lactone synthesized via Pd-catalyzed telomerization of butadiene. As EVP is 28.9% by weight CO2 it has received significant recent attention as an intermediary for the...