(–)-α-Santonin

January 22, 2018
I’m a defunct drug with a brand-new purpose.
What molecule am I?

(–)-α-Santonin, often referred to simply as santonin, is compound isolated from the flowers of the Artemisiagenus of plants found in Russia and central Asia. It was used as anthelmintic, a drug that kills parasitic worms or removes them from the body. But it has severe side effects (see the hazards information box) and has been replaced by much safer ascaricides.

But santonin lives on in organic synthesis. In a recent report, Phil B. Alper and colleagues at the Genomics Institute of the Novartis Research Foundation (San Diego) describe novel photoinduced rearrangements of 2,5-dienones, including santonin.

The authors found that the rearrangements can be “rerouted” in the presence of amines to give previously unknown structures. When they irradiated tricyclic santonin in the presence of methylamine in a continuous-flow reactor, they obtained unusual [4.4.0] and [5.3.0] fused-ring molecules as major products. Elucidation of the precise mechanisms of the phototransformations is under way.

MOTW Updates

Indigo was the Molecule of the Week for April 23, 2012. It is the oldest dye or pigment used by humans; and the manufactured product is still in use today. Recently, John E. Dauber at the University of California, Berkely, developed a biochemical process to make indigo that is not only environmentally “green”, but it also allows cotton fabric to be treated with an indigo precursor, which then oxidizes in place to dye the fabric.

Previous environmentally problematic Molecules of the Week tetrachloroethyleneN-methyl-2-pyrrolidone, and hexabromocyclododecane are in the news again. They are among the chemicals in the “First 10” list for reevaluation under the revised Toxic Substances Control Act of 2016. But last month the Trump administration put additional restrictions of the substances on hold, with no set date for implementation.

(–)-α-Santonin fast facts

CAS Reg. No. 481-06-1
Molar mass 264.30 g/mol 
Empirical formula C15H18O3
Appearance Colorless to yellow crystals 
Melting point 175 ºC 
Water solubility ≈750 mg/L

(–)-α-Santonin hazard information

GHS classification: acute toxicity, oral, category 4
H302—Harmful if swallowed Chemical Safety Warning
GHS classification: acute toxicity, dermal and inhalation, category 2
H310/H330—Fatal in contact with skin or if inhaled Chemical Safety Toxicity Warning
GHS classification: skin irritation, category 2
H315—Causes skin irritation Chemical Safety Warning
GHS classification: eye irritation, category 2A
H319—Causes serious eye irritation Chemical Safety Warning
GHS classification: specific target organ toxicity—single exposure, category 3, respiratory system
H335—May cause respiratory irritation Chemical Safety Warning

*Globally Harmonized System of Classification and Labeling of Chemicals. Explanation of pictograms.

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