How are synthetic alkynes used for birth control?

1 Answer
Oct 26, 2014

Some synthetic alkynes are modifications of naturally-occurring female hormones.

Estradiol and progesterone are two naturally-occurring female hormones.

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Ethinylestradiol, norethindrone, levonorgestrel, and mifepristone are four synthetic alkynes that are used in birth control pills.

Ethinylestradiol

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Estradiol cannot be administered orally because it is rapidly oxidized by the liver.

To prevent oxidation, the 2° alcohol is converted to a 3° alcohol.

Estrone is ethynylated in one step by reaction with ethyne, sodium and sodium amide.

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Ethinylestradiol prevents ovulation.

Norethindrone

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Norethindrone makes it difficult for a fertilized egg to attach to the wall of the uterus.

Levonorgestrel

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Levonorgestrel inhibits ovulation.

Mifepristone

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Mifepristone is often used as a "morning after" pill. If taken before ovulation, it can prevent ovulation and so prevent pregnancy.