An Organocatalytic System for Z -Alkene Synthesis via a Hydrogen-Bonding-Assisted Photoinduced Electron Donor-Acceptor Complex.

A general catalytic donor for the combination of a photoinduced electron donor-acceptor (EDA) complex and energy transfer was developed. This mild and metal-free protocol allows facile access to various Z -alkenes. Mechanism studies revealed that the organophotocatalyst, 4-CzIPN, formed a distinct three-component EDA complex with redox-active esters and (C 6 H 5 O) 2 P(O)OH to trigger the photoredox catalysis. The E → Z isomerization was achieved via electron exchange energy transfer from 4-CzIPN.