A theoretical study of an electronically mismatched Diels–Alder cycloaddition

Abstract

The stepwise mechanism of the Diels–Alder cycloaddition between two electon-rich components.

Confined surface-enhanced indole cation-radical cyclization studied by mass spectrometry

“…In fact, the formation of 1 ˙ + is crucial for the cyclization reaction under mild conditions. 38 As verified (Fig. 3f), the calculated HOMO–LUMO gap between diene and 1 ˙ + is much lower than that between diene and indole, exhibiting electronically matched states under mild conditions.…”

“…The formation of radical cations 1 •+ was further supported by studying the kinetic properties of substrates and catalyst under the theoretical level of UB3LYP/Def2-SVP. 38 Firstly, the electronic states of indole and Ru(bpz) 3 2+ were calculated to evaluate electron transformation among different valence states. As calcu-lated, −0.377 Ha energy was released from the reduction of Ru 4d 6 (Ru 2+ ) that was triggered by one electron transformation.…”

“…37 Simultaneously, oxygen acts as the charge carrier to trigger the charge transfer for converting Ru(bpz) 3 + to Ru(bpz) 3 2+ . 19,38 Thereafter, in the presence of isoprene (2), radical 1 •+ can rapidly undergo an electronically matched Diels-Alder reaction to generate the cationic radical 3 •+ (m/z 185). The generated 3 •+ could abstract one electron from another equivalent of 1 via the chain-propagation step (the dashed line in Fig.…”