The Julia olefination is regiospecific and connective
المؤلف:
Jonathan Clayden , Nick Greeves , Stuart Warren
المصدر:
ORGANIC CHEMISTRY
الجزء والصفحة:
ص686
2025-07-06
636
Sulfoxide eliminations are a valuable way of introducing a double bond to an already intact carbon skeleton. The alkene synthesis we are about to show you is also based on sulfur chemistry, but is connective—the alkene is formed by joining together two separate fragments. It is called the Julia olefi nation and is probably the most important application of the sulfone stabilized anions you saw earlier in the chapter. Only the alkene shown is formed, with the double bond joining the two carbons that carried the PhSO2 and PhCO2 groups. This elimination is promoted by a reducing agent, traditionally sodium amalgam (a solution of sodium metal in mercury) and works for a variety of compounds providing they have a phenyl sulfonyl group adjacent to a leaving group.
Common leaving groups are carboxylates such as acetate or benzoate, and the starting materials are very easily made. The sulfone-stabilized anion adds to aldehydes and a simple esterification step, which can be done in the same reaction vessel, introduces the acetate or benzoate group. This is how the starting material for the elimination above was made.
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