chemistry

Melengestrol

Melengestrol 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 Melengestrol rather than just read about it. In short: Melengestrol (INN, BAN) is a steroidal progestin of the 17α-hydroxyprogesterone group and an antineoplastic drug which was never marketed. An acylated derivative, melengestrol acetate, is used as a growth promoter in animals.

Key takeaways

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

Reference excerpt

Melengestrol (INN, BAN) is a steroidal progestin of the 17α-hydroxyprogesterone group and an antineoplastic drug which was never marketed. An acylated derivative, melengestrol acetate, is used as a growth promoter in animals. While melengestrol is sometimes used as a synonym for melengestrol acetate, what is usually being referred to is melengestrol acetate and not melengestrol.

Synthesis 6-Methyl-16-dehydropregnenolone acetate (5) is the key intermediate to the preparation of both melengesterol acetate and medrogestone. Petrov and his collaborators have devised several interesting schemes that go back to diosgenin as the starting point. These schemes perform the necessary modifications in rings A and B with the sapogenin side chain still in place. In essence this approach employs this side chain as a protecting group for the future 16-dehydro-20-ketone function. In one of these routes, diosgenin is first converted to the 3-toluenesulfonate (1). Solvolysis of this homoallylic alcohol derivative affords the 3,5-cyclosteroid (2), via the cyclopropyl carbinyl ion (carbenium ion) (not shown). (This general reaction was probably first found in the steroids and bore the name of "i-steroid rearrangement.") Oxidation of the product by means of PCC affords the ketone. Reaction of this with methylmagnesium iodide affords two isomeric carbinols with the α-isomer predominating (3). Solvolysis in the presence of a nucleophile such as acetic acid reverses the cyclopropylcarbinyl transformation to afford homoallylic acetate. Removal of the sapogenin side chain leads to the desired product (5).

Substitution at the 16 position was found to lead to further potentiation of progestational activity. Reaction with diazomethane at the conjugated double bond at 16 gives first the pyrazole (6). This heterocycle affords the 16 methyl enone on pyrolysis (7). Selective epoxidation of the conjugated double bond to the 16,17α-epoxide over that at 5,6 is achieved by oxidation with basic hydrogen peroxide (8). Opening of this tetrasubstituted oxirane ring in acid proceeds with loss of a proton from the β position (16 methyl) (9) to afford the desired 16-methylene-17α-hydroxy-20-ketone functionality in the D ring (10). The product is saponified and then the subject of an Oppenauer oxidation, which is then dehydrogenated to the 4,6-diene with chloranil (11). Acetylation under forcing conditions completes the synthesis of melengesterol acetate.

Illustrations

Worked examples

Example 1 — a first encounter with Melengestrol

Start with the simplest possible case. Write down what Melengestrol 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 Melengestrol 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 Melengestrol 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 Melengestrol

In research: Melengestrol 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 Melengestrol 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: Melengestrol is common in secondary-school and first-year university syllabi. It links to neighbouring topics Acetate esters, Antineoplastic drugs, Drugs not assigned an ATC code, so understanding it makes those chapters shorter.
In everyday life: Look for Melengestrol 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 Melengestrol in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Melengestrol 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 Melengestrol out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Melengestrol in simple terms?

Why does Melengestrol 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 Melengestrol?

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 Melengestrol.