Protection‐Group‐Free Synthesis of Sequence‐Defined Macromolecules via Precision λ‐Orthogonal Photochemistry

An advanced light‐induced avenue to monodisperse sequence‐defined linear macromolecules via a unique photochemical protocol is presented that does not require any protection‐group chemistry. Starting from a symmetrical core unit, precision macromolecules with molecular weights up to 6257.10 g mol−1...

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Bibliographic Details
Published in:Angewandte Chemie International Edition 2019-05, Vol.58 (21), p.7133-7137
Main Authors: Konrad, Waldemar, Fengler, Christian, Putwa, Sarrah, Barner‐Kowollik, Christopher
Format: Article
Language:English
Subjects:
Atmospheric chemistry
Carboxylic acids
Chains
cycloaddition
Ionization
Macromolecules
Magnetic resonance spectroscopy
Mass spectrometry
Mass spectroscopy
Monomers
NMR
NMR spectroscopy
Nuclear magnetic resonance
Organic chemistry
Photochemicals
Photochemistry
Photosensitivity
Pyrene
sequence control
sequence-defined macromolecules
sequence-definition
Tetrazoles
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Summary:An advanced light‐induced avenue to monodisperse sequence‐defined linear macromolecules via a unique photochemical protocol is presented that does not require any protection‐group chemistry. Starting from a symmetrical core unit, precision macromolecules with molecular weights up to 6257.10 g mol−1 are obtained via a two‐monomer system: a monomer unit carrying a pyrene functionalized visible light responsive tetrazole and a photo‐caged UV responsive diene, enabling an iterative approach for chain growth; and a monomer unit equipped with a carboxylic acid and a fumarate. Both light‐induced chain growth reactions are carried out in a λ‐orthogonal fashion, exciting the respective photosensitive group selectively and thus avoiding protecting chemistry. Characterization of each sequence‐defined chain (size‐exclusion chromatography (SEC), high‐resolution electrospray ionization mass spectrometry (ESI‐MS), and NMR spectroscopy), confirms the precision nature of the macromolecules. No protection needed: A strategy employing a highly efficient λ‐orthogonal photochemical procedure by selective excitation of photosensitive groups paves the way to precision monodisperse sequence‐defined linear macromolecules without any need for protection‐group chemistry. The chain growth is based on a two‐monomer system that enables protection group free convergent chain extension on‐demand.
ISSN:1433-7851
1521-3773
DOI:10.1002/anie.201901933