Sharpless epoxidation is a useful process which produces nearly pure enantiomers
ID: 483311 • Letter: S
Question
Sharpless epoxidation is a useful process which produces nearly pure enantiomers of epoxides in a predictable way. Which statement is NOT true for the process?
The key chiral reagent used is much cheaper in one enantiomer than the other
The titanium compounds required only are needed in catalytic quantities
The oxidizing agent used is usually t-butyl hydroperoxide
The process has been used in large-scale reactions as well as lab work
The key chiral reagent used is much cheaper in one enantiomer than the other
The titanium compounds required only are needed in catalytic quantities
The oxidizing agent used is usually t-butyl hydroperoxide
The process has been used in large-scale reactions as well as lab work
Explanation / Answer
Answer:
a) Sharpless EEpoxidation : It's an enantioselective chemical reaction used to epoxidate the 1o and 2o allyl alcohol to 2,3-epoxyalcohols.
b) High enantioselectivity in Sharpless Epoxidation is achieved by a catalyst formed from titanium tetra(isopropoxide) and diethyl tartrate. Only 5–10 mol% of the catalyst in the presence of 3Å molecular sieves is necessary.
Hence, Statement (2) : The Titanium compounds required only are needed in catalytic quantities is TRUE.
c) t-Butylhydrogen peroxide is used as an oxidizing agent. Statement 3 is TRUE.
d) Synthesis of intermediates of various natural products: methymycin, erythromycin involves Sharpless epoxidation.Synthesis of various Carbohydrates, Terpenes, Pheromons also involve the Sharpless EPoxidation step.
Statement (4) : The process has been used in large scale reactions as well as lab work.
Hence finally the Statement (1) is NOT TRUE.
Answer option (1)
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