Скачать или смотреть the Wittig reaction

The Wittig reaction involves the reaction of a carbonyl compound (aldehyde or ketone) with a phosphonium ylide. The ylide and carbonyl combine in a reaction that forms an oxaphosphetane intermediate. Oxaphosphetanes are four-membered rings that contain an oxygen and phosphorous. These are unstable structures and quickly decompose to form two new molecules. One molecule is triphenylphosphine oxide (O=PPh3). This is waste in the reaction. The second molecule is an alkene, the desired product. The geometry of the alkene product (E or Z) depends upon the identity of the R-groups on the carbonyl and ylide.