3-Thujone structure

Semmler, F. Ber. derDeutsch Chem. Gesellschaft, 33, 1900, 275-277. (Thujone structure)... 

Thujane-type monoterpenes, unusual monoterpenes with a cyclopropane ring in a bicyclo[3.1.0] skeleton, are formed from the terpinen-4-yl cation directly or via the sabinyl cation. Important members include a-thujene 52, sa-binene 53, the cis isomer 54 of sabinene hydrate, sabinol 55, sabinylacetate 56, a-thujone 57, -thujone 58 and isothujanol 59 (Structure 4.13). 

Earlier preparative work associated with the thujones was primarily directed toward partial synthesis and to denvatization of the natural products in the course of structure proof.3... 

C,oH,jO, Mr 152.24, oil with a menthol-like odor. Bi-cyclic monoterpene ketones with the thujane structure occurring in two C-4-epimeric forms in nature i SAR,5R) -)-a-T, bp. 83.8-84.1 °C (17 hPa), [a]o -19.2° (neat), (15, 4S,5/ )(+)-)S-T., bp. 85.7 -86.2°C (17 hPa), [a]o +72.5° (neat). Not only the names a-and jS-thuJone but also thujone and isothujone are sometimes used incorrectly in the literature. T. are potent neurotoxins, cause epileptic seizures, and can lead to severe psychic damage. It is not yet known if both epimers exhibit the same biological effects. Occurrence Very widely distributed in the essential oils of Asteraceae, Cupressaceae, Lamiaceae, Pina-ceae species. Thuja oil (Thuja occidentalis, Cupressaceae) contains 40% (-)-a-T. and tansy oil (Tanace-tum vulgare, Asteraceae) 58% (+)-/S-T. 

Ketones In general, the ketones found in essential oils can be very toxic (e.g., thujone, the structure of which is shown in Figure 5, and pinopamphone). Flowever, at appropriate concentrations they have useful therapeutic properties, promoting the secretion of mucous and inducing cell and tissue regeneration as well. 

Oil of wormwood was known to be toxic, and around 1900 the structure of thujone was discovered, and it was found to be present in wormwood, thuja oil and tansy oil. As the only component of absinthe to be identified, thujone was seen as a villain, though the evidence is now that absinthe, and thujone in particular, were blamed for large-scale alcoholism. 

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