Addition Coupled Electron Transfer (ACET) and Addition Coupled Electron Coupled Proton Transfer (ACPCET)

The new types of elementary reaction in which a nucleophilic addition (A) to quinones is coupled with electron transfer (ET) and even further proton transfer (PT) are suggested herein by density functional theory calculation, which are called Addition Coupled Electron Transfer (ACET) or Addition Coupled Electron Coupled Proton Transfer (ACPCET). With a [2.2]paracyclophane-derived biquinone (1) as the substrate, the nature of nucleophilic addition onto its sp2 carbons exhibits a change from stepwise A-ET-PT to ACET-PT and further to ACPCET, in parallel with the decreased nucleophilicity of the attacking reagent. In addition, we further proposed six possible potential energy surfaces and the coupling modes between A, ET and PT, in which three have been found in this work. Quasi-classical trajectory shows that the ACET and PT event can also be dynamically concerted even for an ACET-PT mechanism.