The background and recent breakthroughs in the single-electron-transfer (SET) reactions with trivalent tertiary phosphines are summarized and discussed in detail, and an outlook in the developments within this field is provided.

Scheme 4. Scope of Enals 1 and Pyranone Dienones 7 a a Yields are isolated yields after purification by column chromatography. dr values were determined by 1 H NMR on the crude reaction mixture. er values were determined via HPLC on the chiral stationary phase. The absolute configuration of 8b was determined via X-ray analysis of its single crystals.