Radical-promoted single-unit monomer insertion (SUMI) [ aka. reversible-deactivation radical addition (RDRA)]

We survey progress in the development of the processes for radical-promoted single-unit monomer in-sertion (SUMI) or reversible deactivation radical addition (RDRA), focussing on aminoxyl-[nitroxide-] me-diated SUMI (NM-SUMI), reversible-addition-fragmentation chain transfer-SUMI (RAFT-SUMI) , atom -transfer radical addition (ATRA). Radical-promoted thiol-ene processes are also briefly discussed. We de-tail the strategies for achieving selectivity with respect to single unit insertion vs oligomerization and look critically at progress towards discrete oligomer synthesis by consecutive SUMI reactions. We exam-ine the use of SUMI to install alpha-, omega- or mid-chain-functionality in RDRP-synthesized polymers. Finally, we examine the prospects for using radical-promoted SUMI in the synthesis of sequence-defined poly-mers where monomer placement is precisely defined to the level of the individual monomer units in the polymer chain.(c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )

Automated summary

This article surveys the progress in the development of radical-promoted single-unit monomer insertion (SUMI) or reversible deactivation radical addition (RDRA) processes, with a focus on aminoxyl-[nitroxide-] mediated SUMI (NM-SUMI), reversible-addition-fragmentation chain transfer-SUMI (RAFT-SUMI), and atom-transfer radical addition (ATRA). The strategies for achieving selectivity in single unit insertion vs oligomerization and the progress towards discrete oligomer synthesis by consecutive SUMI reactions are discussed. The prospects of using radical-promoted SUMI in the synthesis of sequence-defined polymers are also examined.