Methyl dihydrojasmonate

A commercially important outlet in the fragrance industry is the methyl dihydrojasmonate [24851-98-7] (26) which is made by Michael addition of a malonate to 2-pentyl-2-cyclopenten-l-one [91791 -21 -8] (52) and which is used in perfumery for blossom fragrances, particularly jasmine (see Perfumes). 

Decenoic acid (143), easily prepared from the same telomer 142, was cyclized via acid chloride using A1C13 to give 2-pentyl-2-cyclopentenone (144). Michael addition of methyl malonate followed by removal of one ester group produced methyl dihydrojasmonate (145) (129) ... 

Dihydrojasmonates are ubiquitous and cheap perfume ingredients. Firmenich established that (+)-cis-methyl dihydrojasmonate (Fig. 37.20) is the preferred stereoisomer, and subsequently developed an enantioselective process and began production on a multi-ton per year scale [82, 83]. 

The chemical structures of the majority of FMs that have been studied in wastewater treatment are given in Figs. 1-3. Figure 1 shows a variety of FM structures that include alcohols, aldehydes, and ketones, including benzyl acetate (phenylmethyl ester acetic acid), methyl salicylate (2-hydroxy-methyl ester benzoic acid), methyl dihydrojasmonate (3-oxo-2-pentyl-methyl ester cyclopentaneacetic acid), terpineol (4-trimethyl-3-cyclohexene-1-methanol), benzyl salicylate (2-hydroxy-phenylmethyl ester benzoic acid), isobornyl acetate... 

Primary+secondary removal benzyl acetate=86.4-99.9 methyl salicylate=92.0-99.9 methyl dihydrojasmonate=81.9-99.9 terpineol=95.4-99.9 benzyl salicylate=90.3-99.9 isobornyl acetate=84.5-99.9 g-methyl ionone=83.1-99.8 p-f-bucinal=84.8-99.3 hexylcinnamaldehyde=95.3-99.9 hexyl salicylate=96.4-99.9 OTNE=51.4-99.4 acetyl cedrene=71.3-99.9... 

Of the four possible optical isomers, the (+)-( I )-cw-isomer possesses the most characteristic jasmin odor. Methyl dihydrojasmonate is prepared by Michael addition of malonic acid esters to 2-pentyl-2-cyclopenten-l-one, followed by hydrolysis and decarboxylation of the resulting (2-pentyl-3-oxocyclopentyl) malonate, and esterification of the (2-pentyl-3-oxocyclopentyl)acetic acid [136]. 

Methyl dihydrojasmonate is used in perfumery for blossom fragrances, particularly in jasmin types. 

Firmenich has reported the asymmetric hydrogenation of an a,P-unsaturated ketone (62) with rhodium catalysts that contains 4b to give (+)-ri.s-methyl dihydrojasmonate (63) in 90% ee (Scheme 12.19). The product, which is a fragrance, has been performed at the multi-100-kg scale with increased production planned.87,88... 

A Me-DuPhos-ruthenium catalyst has found application in the industrial synthesis of the fragrance (+)-d.v-methyl dihydrojasmonate 60 (Scheme 13.18).64 The catalyst gave excellent m-selectivity, and although the enantiomeric excess was modest (76%), it was acceptable for use of the product in perfumery. 

Fig. 3.25 Production of (+) cis-methyl dihydrojasmonate using Ru-Josiphos catalyzed hydrogenation.

The 3,3-sigmatropic Feairangement of 2-octenyl vinyl ether (39) afforded 3-pentyl-4-pentenal (40) in 79% yield. The terminal double bond was conveited to the methyl ketone (41) in 90% yield. The keto aldehyde (41) was converted to 5-pentyl-2-cyclopentenone (42). The double bond migration gave 2-pen-tyl-2-cyclopentenone (dihydronorjasmone), which was converted to methyl dihydrojasmonate (43 Scheme 11),108>>09 Similarly, dihyctojasmone was synthesized from 2-octenyl allyl edier. 

Vinyl 2-octenyl ether 106, obtained from 2,7-octadienyl acetate (56) is converted to the aldehyde 107 in 79% yield by [3,3] sigmatropic rearrangement at 183-190 C.Then PdCl2-catalyzed oxidation of the double bond to the ketone 108 followed by intramolecular aldol condensation gives the 2-cyclopentenone 109 in 68% yield, which is converted to methyl dihydrojasmonate (ii0)40. Treatment of allyl 2-octenyl... 

Esters, such as ethyl acetate, linalyl acetate, ethyl phenyl acetate, and methyl dihydrojasmonate... 

Plaquevent and coworkers synthesized methyl dihydrojasmonate 28 using this methodology by performing the asymmetric Michael addition of dimethyl malonate 29 on 2-pentyl-2-cydopentenone 30 [18]. The mechanism involved the tandem deprotonation of the malonate 29 using solid-liquid phase-transfer catalysis... 

Scheme 7.14 Plaquevent s asymmetric synthesis of methyl dihydrojasmonate [18].

Corey s methodology was also successfully applied by Plaquevent and coworkers to the synthesis of chiral methyl dihydrojasmonate (31), which has a jasmine-like odor. The reaction of a-pentyl cyclopentanone (29) and dimethyl malonate under PTC conditions (11 mol% of 28, K2C03 (0.16 equiv.) at —20 °C) gave the key intermediate 30 for the synthesis of methyl dihydrojasmonate 31 in 91% yield and with 90% ee (Scheme 9.11) [11]. 

Intramolecular Friedel-Crafts acylation provides a useful synthetic approach to cyclic ketones. The cyclization is well-suited to the preparation of six- and particularly five-membered rings, as used in key steps in routes to methyl dihydrojasmonate (equation 3), and precursors to some marine sesquiterpenes (equation 4) and the theoretically interesting spiro[4.4]nonatetraene (equation 5). Extension to cyclo-heptanones has been achieved, - but tars were formed on attempting to prepare cyclooctanones. ... 

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