Intermolecular [2+2] Photocycloaddition of β-Nitrostyrenes to Olefins upon Irradiation with Visible LightFinancial support by the European Research Council under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 665951 – ELICOS) is gratefully acknowledged.
Received: 19 June 2017
Accepted after revision: 30 June 2017
31 August 2017 (eFirst)
Dedicated to Victor Snieckus, a dear colleague and friend, on the occasion of his 80th birthday
The title compounds were found to undergo a [2+2] photocycloaddition with olefins at λ = 419 nm in CH2Cl2 as the solvent. The resulting cyclobutanes were isolated in yields of 32–87% (11 examples) and showed a defined relative configuration at C1/C4 in the major diastereoisomer (nitro and aryl trans). The analysis of side products and triplet sensitization experiments support a mechanistic scenario in which a 1,4-diradical is formed as a key intermediate.