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Chemistry · Glossary

What is Sharpless epoxidation?

Definition 28.20 University Chemistry — Year 3 · Chapter 28 — Asymmetric Synthesis

The Sharpless epoxidation is the enantioselective epoxidation of allylic alcohols by tert-butyl hydroperoxide, catalysed by titanium(IV) isopropoxide with an enantiopure diethyl tartrate; the alcohol binds to titanium, which delivers the oxygen to one face of the alkene, chosen by the tartrate.

Sharpless’s mnemonic. With the allylic alcohol drawn in the plane, the CH2OH group at the lower right, L-(+)-diethyl tartrate delivers the oxygen from below the plane and D-(-)-diethyl tartrate from above, whatever the substituents R1 to R3.
Sharpless’s mnemonic. With the allylic alcohol drawn in the plane, the CHX2OH\ce{CH2OH} group at the lower right, L-(++)-diethyl tartrate delivers the oxygen from below the plane and D-(−-)-diethyl tartrate from above, whatever the substituents R1\mathrm R^1 to R3\mathrm R^3.
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