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Asymmetric Epoxidation Exemplified Facial Descriptors: Re and Si	K. Barry Sharpless Co-Nobelist 2001 Lecture: Video Text Asymmetric Epoxidation and Dihydroxylation

 

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Reading Assignment:

On the Epoxidation of Alkenes

Sharpless Asymmetric Dihydroxylation

Enrichment Assignment:

Professor Sharpless visits Chem 125

Diethyl ether (ether) may well be the first organic compound prepared that does not appear in Nature. For a chemical history of ether click here. A different Powerpoint version is here.
Theory of Etherification, A. W. Williamson, Quarterly J. Chem. Soc., 1852, 4, 106. [See page 106 in the .pdf file.]

"The following experiments were made with the view of obtaining new alcohols, by substituting carburetted hydrogen for hydrogen in a known alcohol. Iodide of potassium was readily formed on the application of a gentle heat, and the desired substitution was effected; but, contrary to expectation, the compound thus formed had none of the properties of an alcohol -- it was nothing else than common ether, C⁴H¹⁰O." On Etherification, A. W. Williamson, Quarterly J. Chem. Soc., 1852, 4, 229.

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1. Each of the following reactions is missing a reactant, reagent and/or product. Provide the missing items along with an explanation. Answer any questions.

2. Identify each of the structures below. Pay attention to stereochemistry. Pay attention to the equilibrium arrows in the equilibria among B, C and D.

 

3. Toprol (4; Lopressor; Metoprolol) is a β-blocker used for the treatment of hypertension. It is a racemic drug sold as its monosuccinate salt. A seasoned chemist wants to prepare Toprol as its (R)-enantiomer using the synthesis of the racemate. She follows the steps shown on the right. a) Why is Toprol a racemate? b) Draw a structure of the (±)-succinate salt. c) What is the role of aq. NaOH? Check here. d) What is the structure and CIP designation for 3? e) What does the sequence of reactions and their chirality tell you about the mechanism of the double SN2 reaction sequence? e) Write mechanisms for the two reactions. f) How can she prepare (S)-4 without resorting to the use of (R)-1?