TY - JOUR

T1 - Clicking together Alkynes and Tetracyanoethylene

AU - Nielsen, Mogens Brøndsted

N1 - Publisher Copyright: © 2023 The Authors. ChemPhysChem published by Wiley-VCH GmbH.

PY - 2023

Y1 - 2023

N2 - The [2+2] cycloaddition – retro-electrocyclization (CA-RE) reaction allows ready synthesis of redox-active donor-acceptor chromophores from an electron-rich alkyne and electron-poor olefins like tetracyanoethylene (TCNE). The detailed mechanism of the reaction has been subject of both computational and experimental studies. While several studies point towards a stepwise mechanism via a zwitterionic intermediate for the first step, the cycloaddition, the reaction follows neither simple second-order nor first-order kinetics. Recent studies have shown that the kinetics can be understood if an autocatalytic step is introduced in the mechanism, in which complex formation with the donor-substituted tetracyanobutadiene (TCBD) product possibly facilitates nucleophilic attack of the alkyne onto TCNE, generating the zwitterionic intermediate of the CA step. This Concept highlights the convenient use of the “click-like” CA-RE reaction to obtain elaborate donor-acceptor chromophores and the recent mechanistic results.

AB - The [2+2] cycloaddition – retro-electrocyclization (CA-RE) reaction allows ready synthesis of redox-active donor-acceptor chromophores from an electron-rich alkyne and electron-poor olefins like tetracyanoethylene (TCNE). The detailed mechanism of the reaction has been subject of both computational and experimental studies. While several studies point towards a stepwise mechanism via a zwitterionic intermediate for the first step, the cycloaddition, the reaction follows neither simple second-order nor first-order kinetics. Recent studies have shown that the kinetics can be understood if an autocatalytic step is introduced in the mechanism, in which complex formation with the donor-substituted tetracyanobutadiene (TCBD) product possibly facilitates nucleophilic attack of the alkyne onto TCNE, generating the zwitterionic intermediate of the CA step. This Concept highlights the convenient use of the “click-like” CA-RE reaction to obtain elaborate donor-acceptor chromophores and the recent mechanistic results.

KW - alkynes

KW - chromophores

KW - click chemistry

KW - cycloaddition

KW - retro-electrocyclization

U2 - 10.1002/cphc.202300236

DO - 10.1002/cphc.202300236

M3 - Journal article

C2 - 37232195

AN - SCOPUS:85161977074

VL - 24

JO - ChemPhysChem

JF - ChemPhysChem

SN - 1439-4235

IS - 15

M1 - e202300236

ER -