CH610B Sophomore Organic II

Dr. Brian Pagenkopf

The Wittig Reaction:

Above is shown the simplest Wittig reagent, namely the ylide made from a methyl halide and triphenyl phosphine. Note how in the electrostatic potential surface the negative charge is on the carbon atom, explaining why it is such a good nucleophile and reacts with carbonyl groups.

Shown here is the four-membered ring intermediate that occurs when the Wittig reagent derived from a methyl halide reacts with acetone. The unique feature of the Wittig reaction is the mechanism in which the famous four-membered ring intermediate, called an oxaphophetane, is formed.

The Wittig Reaction is great for converting aldehydes and ketones into alkenes! Although there are two competing models on the correct mechanism for this reaction, we can employ what we already know to explain it.

Sources include http://www.cm.utexas.edu/academic/courses/Spring2001/CH610B/Iverson/index.html