Diethyl tartrate

Diethyl tartrate is an organic compound, the ethyl ester of tartaric acid. It exists in both as a chiral isomer, showing both left- and right-handed forms, as well as a meso stereoisomer, which is not chiral. The chiral isomer is far more common.
In the Sharpless epoxidation, diethyl tartrate and titanium isopropoxide form a chiral catalyst in situ.