Methyl jasmonate synthesis

Allyl aryl ethers are used for allylation under basic conditionsfh], but they can be cleaved under neutral conditions. Formation of the five-membered ring compound 284 based on the cyclization of 283 has been applied to the syntheses of methyl jasmonate (285)[15], and sarkomycin[169]. The trisannulation reagent 286 for steroid synthesis undergoes Pd-catalyzed cyclization and aldol condensation to afford CD rings 287 of steroids with a functionalized 18-methyl group 170]. The 3-vinylcyclopentanonecarboxylate 289, formed from 288, is useful for the synthesis of 18-hydroxyestrone (290)[I7I]. 

When the cyclic enone is unsubstituted, but the resulting enolate is quenched with an electrophile under conditions of kinetic control the irons adduct is formed exclusively303. Particularly successful is the sequential Michael addition/enolate alkylation in diastereoselective routes to frans-a,/j-difunctionalized cycloalkanones and lactones304-308. The key steps in the synthesis of methyl ( + )-jasmonate (3)309-310 (syn/anti diastereoselection) and (-)-khushimone (4) (syn/anti and induced diastereoselection) illustrate this sequence311 (see also Section D. 1.1.1.3.). 

Inomata100 utilized a tandem retro-Diels-Alder-ene reaction for an enantioselective total synthesis of (+)-methyl jasmonate (Scheme 41). The TMS group on the alkene was essential to the efficiency of the reaction, by producing a higher energy level of the HOMO for the ene reaction. 

Dihydro-1,3-oxazines have served both as nucleophilic and electrophilic agents in the preparation of carbonyl compounds. The multiple uses of this heterocycle are nicely revealed in the synthesis of methyl jasmonate (739) (73JOC175). 

Several applications in total syntheses exemplify the value of this methodology 11-oxoequiienin methyl ether (101 Scheme 38),105 107 (+)-a-cuparenone,109 (-)-podorhizon,112 (-)-methyl jasmonate (102 Scheme 39),114 (+)-estrone methyl ether,116 and the so called (+)-A-factor (103 Scheme 40)117 were all prepared in high enantiomeric purity. Other applications constitute preparations of 2-alkylchro-man-4-ones,118 and of 3-vinylcyclopentanones, highly valuable intermediates for steroid total synthesis.106,107... 

Dehydrogenation of an allyl 0-ketocarboxylate is a key step in a synthesis of methyl jasmonate that has been reported.362... 

Michael addition.1 This ketene silyl acetal undergoes Michael addition to a,fl-enones in acetonitrile in the absence of a Lewis acid to afford the corresponding O-silylated Michael adduct in high yield. These O-silyl enolates undergo site-specific electrophilic substitution. This sequence was used for vicinal dialkylation of cyclohexanone (equation I) and of cyclopentanone. It is particularly useful for synthesis of methyl jasmonate and related compounds from cyclopentenone. 

The jasmonates are another class of disubstituted cyclopentanoid natural products very reminiscent of the prostaglandins. To efficiently assemble their main skeleton, Yamamoto and co-workers developed a clever three-component reaction methodology that was demonstrated by the total synthesis of both trans- and cis-methyl jasmonates 36 and 37 (Scheme 12.7) [25],... 

FARMER, E.E., RYAN, C.A., Interplant communication airborne methyl jasmonate induces synthesis of proteinase inhibitors in plant leaves, Proc. Natl. Acad. Sci. USA, 1990, 87, 7713-7716. 

AERTS, R GISI, D DE CAROLIS, E DE LUCA, V., BAUMANN, T.W., Methyl jasmonate vapor increases the developmentally controlled synthesis of alkaloids in Catharanthus and Cinchona seedlings. Plant J., 1994,5,635-643. 

OL, -Bifunctionalization of cyclopentenone.1 Although simple ester enolates do not undergo conjugate additions, the enolate of 1 undergoes conjugate addition to cyclopentenone in THF/HMPT (3.3 1) at -20°. This reaction coupled with in situ enolate alkylation provides a notably short synthesis of methyl jasmonate (3). 

Michael additions. Gerlach and Kiinzler report that the lithium enolate of S-t-butyl thioacetate undergoes 1,4-addition to cyclopentenone. They have extended this Michael reaction to a synthesis of methyl jasmonate (5), based on the similar conjugate addition of the trimethylsilyl enolate 1 promoted by tetra-n-butylam-monium fluoride. The adduct 2 was alkylated by l-bromo-2-pentyne in the presence of tetra-n-butylammonium fluoride to give 3 in rather low yield. Remaining steps to 5 were methanolysis and partial hydrogenation of the triple bond. 

Generation of the endocyclic double bond of cyclopentanoids has been accomplished frequently by rDA reaction of the appropriate cyclopentadiene. FVP has been used as the last step of the synthesis of the antibiotic ( )-pentenomycin (53) in 50% yield. " Other cyclopentanoid natural products that are synthesized by procedures based upon a nearly quantitative rDA reaction are jasmone (54) and alkyne (55), a precursor to methyl jasmonate. This same procedure has been applied to the synthesis of intermediates of prostaglandins such as (56). ... 

Synthesis of methyl jasmonate (8). Meyers and Nazarenko have reported a synthesis of methyl jasmonate (8), a constituent of the characteri.stic odor of jasmine,... 

One typical example is given by the asymmetric synthesis of (-)-methyl jasmonate (Scheme 43). ... 

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