C/s-Jasmone

Finally, there has been speculation and recent experimental support for the involvement of a Nazarov-type cyclization in the biosynthesis of c/ s-jasmonic acid ° and marine-derived prostanoids. Radiolabel tracer studies have demonstrated Ae intermediacy of 8-HPETE (104) in the biosynthesis of prostanoid intermediate preclavulone A (lO ). This remarkable conversion was proposed to proceed by formation of allene oxide (105) followed by isomerization to (107) via the 2-oxidocyclopentadienyl cation (106 Scheme 41). To demonstrate the chemical feasibility of this proposal, Corey reported the transformation of epoxysilane (108) to, inter alia, the cyclopentenone (111 Scheme 42). The reaction is presumed to involve formation of the allene oxide (109) followed by isomerization to the 2-oxi-dopentadienylic cation (110). Conrotatory closure of (110) is expected to produce the cis isomer of (111) as observed. 

ProbiGm 12.10 What is the structute of c/s-jasmone, a natural product isolated from jasmine flowers, formed by treatment of alkyne A with H2 in the presence of the Lindlar catalyst ... 

What starting material would be required for formation of the natural product c/s-jasmone by an intramolecular aldol reaction (Chapter 27) How would you make this compound using a Stetter reaction ... 

CnHigO, Mt 166.26, bp2j kPa 87-88 °C, d25 0.9157, n 1.4771, is a colorless, slightly viscous liquid with a typical jasmine odor, resembling that of the naturally occurring c/s-jasmone. Dihydrojasmone can be synthesized by various routes. A preferred method is intramolecular aldol condensation of 2,5-undecanedione, which can be prepared from heptanal and 3-buten-2-one in the presence of a thiazolium salt, such as 5-(2-hydroxyethyl)-4-methyl-3-benzylthiazolium chloride [120] ... 

ChHi60, Mr 164.25, bpi kPa 78-79 °C, tfi° 0.9423, n 1.4989 occurs in jasmine absolute and contributes to its typical jasmine odor. It is a pale yellow, viscous liquid with a strong jasmine odor. Various stereospecific syntheses for c/s-jasmone have been reported. A patented method involves alkylation of 3-methyl-2-cyclopen-ten-l-one with cz. y-2-pentenyl chloride in an alkaline medium in the presence of a phase-transfer catalyst (e.g., tricaprylmethylammonium chloride) [121] ... 

This chemistry was used to make the perfume c/s-jasmone by R. A. Ellison and W. D. Woessner, J. Chem. Soc, Chem. Commun., 1972,529. 

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