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Cis Jasmone

http://amcrasto.wix.com/anthony-melvin-crasto/apps/blog/cis-jasmone
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Jasmone is a natural organic compound extracted from the volatile portion of the oil fromjasmine flowers. It is a colorless to pale yellow liquid that has the odor of jasmine. Jasmone can exist in two isomeric forms with differing geometry around the pentenyl double bond, cis-jasmone and trans-jasmone. The natural extract contains only the cis form, while synthetic material is often a mixture containing both forms, with the cis form predominating. Both forms have similar odors and chemical properties.

Jasmone is produced within plants by the metabolism of jasmonate, from linolenic acid by the octadecanoid pathway. It can act as either an attractant or a repellent for various insects. Commercially jasmone is used primarily in perfumes and cosmetics.

An attempt to make Z jasmone – an important constituent of many perfumes

In fact one synthesis uses the following as carbon sources:

cis (Z) jasmone ,

cas no 488-10-8, 3-methyl-2-[(2Z)-pent-2-en-1-yl]cyclopent-2-en-1-one

ref-(Can. J. Chem. 1978, Vol 56, p2301)

1    W. Theilheimer. Synthetic Methods of Organic Chemistry. Volume 31, 1977, p. 352 
2   Tetrahedron, 39 (24), p. 4127, 1983

Thomas Koch, Katja Bandemer, Wilhelm Boland (1997). "Biosynthesis of cis-Jasmone: a pathway for the inactivation and the disposal of the plant stress hormone jasmonic acid to the gas phase?". Helvetica Chimica Acta 80 (3): 838–850.doi:10.1002/hlca.19970800318.

Predict NMR spectrum

Formula: C10H14O
CAS#: 488-10-8
MW: 150.22






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Stereochemistry of [n,m] Sigmatropic Rearrangements

July 30, 2012



Stereochemistry of [n,m] Sigmatropic Rearrangements

Basically, [n,m] sigmatropic rearrangements can proceed through a chair or boat  transition state. Only the chair transition state has been observed experimentally though both are suprafacial and are allowed in 4n+2 electron systems.


Chair and boat transition states in [n,m] sigmatropic rearrangements
Fig.1Chair



Fig.2Boat



Examples for sigmatropic rearrangements with a chair transition state

 Fig.3Cope rearrangement

 



Fig.4[3,3] Sigmatropic

               
                        6 Electrons
                   
                        Hückel aromatic
                   
                        Supra-supra


 view animation, 2D Animation of the Cope rearrangement

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http://www.chemgapedia.de/vsengine/supplement/Vlu/vsc/en/ch/2/vlu/pericyclische_reaktionen/pericyclisch_sigmatrop.vlu/Page/vsc/en/ch/2/oc/reaktionen/formale_systematik/pericyclische_reaktionen/sigmatrop/stereochemie_n_m.vscml/Fragment/0d47d3304bb08cfd9c68c1c3590965d2-19.html


Large substituents similar to their behavior in chair conformations of cyclohexane rings prefer an equatorial configuration in the transition state of [3,3] sigmatropic reactions. Heating S,S-3,4-dimethyl-1,5-hexadiene to approximately 200°C  yields in 90% a product derived from a chair transition state with equatorial methyl groups.  The product arising from a diaxial conformation is formed in only 10% yield. Obviously, the reaction does not proceed through the boat transition state.

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