Chemistry:Allene oxide
In organic chemistry, an allene oxide is an epoxide of an allene. The parent compound 2-Methylideneoxirane ({{{2}}}), also known as allene oxide, is CH
2=C(–O–)CH
2, a rare and reactive species of only theoretical interest.
Certain derivatives can be prepared by epoxidation of the allenes with peracetic acid. Typical allene oxides require steric protection for their isolation. They readily rearrange to cyclopropanones via an oxyallyl intermediate.[1][2]
Despite the esoteric character of synthetic allene oxides, allene oxides occur naturally. They are intermediates in the chemical defense of some plants against attack by herbivores. Specifically, a hydroperoxide of linolenic acid is the substrate for the enzyme allene oxide synthase. The resulting allene oxide in turn is converted by allene oxide cyclase to jasmonic acid.[3]
Nevertheless, allene oxides are extremely unstable even in biological contexts, decomposing with a half-life of approximately 15–30 s.[5]
References
- ↑ "Chemistry of Allene Oxides". Tetrahedron 36 (16): 2269–2289. January 1980. doi:10.1016/0040-4020(80)80123-2.
- ↑ Hess, B. Andes Jr.; Eckart, U.; Fabian, J. (1 December 1998). "Rearrangements of Allene Oxide, Oxyallyl, and Cyclopropanone". Journal of the American Chemical Society 120 (47): 12310–12315. doi:10.1021/ja9821652.
- ↑ "Enzymes in jasmonate biosynthesis - structure, function, regulation". Phytochemistry 70 (13–14): 1532–1538. September 2009. doi:10.1016/j.phytochem.2009.07.032. PMID 19703696. Bibcode: 2009PChem..70.1532S.
- ↑ Medicinal Natural Products: A Biosynthetic Approach. United Kingdom: John Wiley & Sons, Ltd.. 2009. pp. 42–53. ISBN 978-0-470-74168-9.
- ↑ "Isolation and characterization of natural allene oxides: unstable intermediates in the metabolism of lipid hydroperoxides". Proceedings of the National Academy of Sciences of the United States of America 85 (10): 3382–3386. May 1988. doi:10.1073/pnas.85.10.3382. PMID 2835769. Bibcode: 1988PNAS...85.3382B.
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