Organic Multi-step Synthesis: Step 1 – The Wittig Reaction

Many reactions in chemistry form carbon-carbon bonds. The Wittig Reaction discovered in 1954 by Nobel laureate George Wittig, is one of the most reliable ways of forming new carbon-carbon double bonds. Because it is so reliable, it is commonly used in organic synthesis to prepare alkenes. With an aldehyde or ketone as a starting reagent in the presence of an organophosphorus ylide (a compound containing a charged phosphorus atom that is adjacent to an oppositely charged organic atom) an organophosphine oxide and an alkene will be formed.

One of the main forces driving the Wittig reaction to completion is the stability gained through the progression from the relatively unstable cyclobutane intermediate to organophosphine oxide product.

Typically, the chemistry of the ylide and its preparation is also explored. As mentioned previously an organphosphorus ylide, often called the Wittig Reagent, refers to a compound containing a charged phosphorus atom that is adjacent to an oppositely charged organic atom. These types of molecules have two forms, their charged (ylide) form or their uncharged (phosphorane) form