Wittig Reaction: Converting Carbonyls into Alkenes
Master the Wittig reaction: ylide formation, betaine/oxaphosphetane intermediates, and alkene formation driven by Ph3P=O. Learn E vs Z selectivity and common exam traps.
Key nucleophile: Phosphorus ylide (Ph3P=CHR)
Electrophile: Aldehyde/ketone
Driving force: Formation of strong Ph3P=O bond
Selectivity shortcut: Non‑stabilized ylides often favor Z; stabilized ylides often favor E (general trend)
Big exam task: Draw starting materials for a target alkene (retrosynthesis)