chemistry

Wieland–Miescher ketone

Wieland–Miescher ketone is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Wieland–Miescher ketone rather than just read about it. In short: The Wieland–Miescher ketone is a racemic bicyclic diketone (enedione) and is a versatile synthon which has so far been employed in the total synthesis of more than 50 natural products, predominantly sesquiterpenoids, diterpenes and steroids possessing possible biological properties including anticancer, antimicrobial, antiviral, antineurodegenerative and immunomodulatory activities. The reagent is named after two ch…

Key takeaways

Wieland–Miescher ketone belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Wieland–Miescher ketone to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Wieland–Miescher ketone from memory before moving on to harder problems.

Reference excerpt

The Wieland–Miescher ketone is a racemic bicyclic diketone (enedione) and is a versatile synthon which has so far been employed in the total synthesis of more than 50 natural products, predominantly sesquiterpenoids, diterpenes and steroids possessing possible biological properties including anticancer, antimicrobial, antiviral, antineurodegenerative and immunomodulatory activities. The reagent is named after two chemists from Ciba Geigy, Karl Miescher and Peter Wieland (not to be confused with Heinrich Otto Wieland). Examples of syntheses performed using the optically active enantiomer of this diketone as a starting material are that of ancistrofuran and the Danishefsky total synthesis of Taxol. Most advances in total synthesis methods starting from Wieland–Miescher ketone were fueled by the search for alternative methods for the industrial synthesis of contraceptive and other medicinally relevant steroids, an area of research that flourished in the 1960s and 1970s. Wieland–Miescher ketone contains the AB-ring structure of steroids and is for this reason an attractive starting material for the steroid skeleton, an approach used in one synthesis of adrenosterone. The original Wieland–Miescher ketone is racemic and prepared in a Robinson annulation of 2-methyl-1,3-cyclohexanedione and methyl vinyl ketone. The intermediate alcohol is not isolated. An enantioselective synthesis employs L-proline as an organocatalyst:

This reaction was reported in 1971 by Z. G. Hajos and D. R. Parrish. In their patent, the isolation and characterization of the above pictured optically active intermediate bicyclic ketol (in parentheses) has also been described, because they worked at ambient temperature in anhydrous dimethylformamide (DMF) solvent. Working in DMSO solvent does not allow isolation of the bicyclic ketol intermediate, it leads directly to the optically active bicyclic dione. The reaction is called the Hajos-Parrish reaction or the Hajos-Parrish-Eder-Sauer-Wiechert reaction. This reaction has also been performed in a one-pot procedure, leading to 49% yield and 76% enantiomeric excess (ee):

Other proline-based catalysts have been investigated.

References

Illustrations

Worked examples

Example 1 — a first encounter with Wieland–Miescher ketone

Start with the simplest possible case. Write down what Wieland–Miescher ketone claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Wieland–Miescher ketone before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Wieland–Miescher ketone ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Wieland–Miescher ketone

In research: Wieland–Miescher ketone appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Wieland–Miescher ketone in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Wieland–Miescher ketone is common in secondary-school and first-year university syllabi. It links to neighbouring topics Bicyclic compounds, Ketones, so understanding it makes those chapters shorter.
In everyday life: Look for Wieland–Miescher ketone outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Wieland–Miescher ketone in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Wieland–Miescher ketone means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Wieland–Miescher ketone out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Wieland–Miescher ketone in simple terms?

Why does Wieland–Miescher ketone matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Wieland–Miescher ketone?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Wieland–Miescher ketone.