Analysis of information sources in references of the Wikipedia article "Levonorgestrel" in Vietnamese language version.
The gonanes share the structural modifications found in the estranes and also possess [an ethyl] group at the position 13 and a keto group at position 3. Norgestrel was synthesized in 1963 and is a racemic mixture of dextro and levorotatory forms. The levorotatory form, levonorgestrel, provides the biological activity.
[Levonorgestrel (24): The product generated by Smith's norgestrel total synthesis was a racemate, so half of each consisted of the left- and the right-handed enantiomer. Chemists at Schering discovered that only the levorotatory enantiomer was effective [49] and developed a biotechnological process for the preparation of the pure levorotatory enantiomer. This was the active ingredient levonorgestrel born. With the single-acting enantiomer, the dose and thus the liver burden could be halved again. The resulting Neogynon® contained 0.25 mg levonorgestrel and 0.05 mg ethinylestradiol and was introduced in 1970.]
