Direct Cyclopropanation of α‐Cyano β‐Aryl Alkanes by Light Mediated Single Electron Transfer between Donor‐Acceptor Pairs

LI, Jing, Lear, Martin and Hayashi, Yujiro (2021) Direct Cyclopropanation of α‐Cyano β‐Aryl Alkanes by Light Mediated Single Electron Transfer between Donor‐Acceptor Pairs. Chemistry - A European Journal, 27 (19). pp. 5901-5905. ISSN 0947-6539

Full content URL: https://doi.org/10.1002/chem.202100341

Documents
Direct Cyclopropanation of α‐Cyano β‐Aryl Alkanes by Light Mediated Single Electron Transfer between Donor‐Acceptor Pairs
Accepted Manuscript

Request a copy
[img] PDF
chem.202100341 - Lear.pdf - Whole Document
Restricted to Repository staff only until 9 February 2022.

1MB
Item Type:Article
Item Status:Live Archive

Abstract

Cyclopropanes are traditionally prepared by the formal [2+1] addition of carbene or radical based C1 units to alkenes. In contrast, the one pot intermolecular cyclopropanation of alkanes by redox active C1 units has remained unrealised. Herein, we achieved this process simply by exposing β‐aryl propionitriles and C1 radical precursors ( N ‐oxy esters) to base and blue light. The overall process is redox‐neutral and a photocatalyst, whether metal‐ or organic‐based, is not required. Our findings support that single electron transfer (SET) from the α‐cyano carbanion of the propionitrile to the N ‐oxy ester is facilitated by blue‐light via their electron donor‐acceptor (EDA) complex. The α‐cyano carbon radical thus formed can then lose a β‐proton to form a π‐resonance stabilised radical anion that preferentially couples at the benzylic β‐position with a decarboxylated C1 radical unit. This new transition metal‐free chemistry tolerates both electron rich and electron deficient (hetero)aryl systems, even sulfide or alkene functionality, to afford a range of cis ‐aryl/cyano cyclopropanes bearing congested tetrasubsitituted quaternary carbons.

Keywords:Organic methods, Cyclopropanation, Single electron transfer, Radical chemistry
Subjects:F Physical Sciences > F160 Organic Chemistry
Divisions:College of Science > School of Chemistry
ID Code:43973
Deposited On:25 Feb 2021 12:17

Repository Staff Only: item control page