2-CYCLOPENTEN-l-ONE, 3-METHYL-2-PENTYL

Cyclopentanes, synthesis, 66, 10 CYCLOPEKTANONE SYNTHESIS, 66, 87, 92, 93 Cyclopentanone, 2-carbomethoxy-3-vinyl, 66, 56 Cyclopentanone, 2-ethenyl-2-methyl (88729-76-4), 66, 94 2-CYCLOPENTEN-l-ONE, 3-METHYL-2-PENTYL-, 65, 26 Cyclopropane, l-trimethy1s1lyloxy-1-ethoxy-, 56, 44 Cyclopropanecarboxylic acid chloride, 66, 176... 

METHYL-2-PEtfTYL-2-CYCLOPEKTEN-l -ONE 2-CYCLOPENTEN-l -ONE, 3-METHYL-2-PENTYL- (1128-08-1), 65, 26... 

Methyl-2-pentyl-2-cyclopenten-l-one 2-Cyclopenten-l-one, 3-methyl-2-pentyl - (8,9) (1128-08-1)... 

Stetter H, Kuhhnann H, Haese W (1987) The Stetter reaction 3-methyl-2-pentyl-2-cyclo-penten-l-one (dihydrojasmone) (2-cyclopenten-l-one, 3-methyl-2-pentyl-). Org Synth 65 26-31 Stetter H, Kuhhnann H (1991) The catalyzed nucleophilic addition of aldehydes to electrophilic double bonds. Org React 40 407 96... 

Diketones are readily transformed to cyclic derivatives, such as cyclopentanones and furans. In this manner, the fragrance dihydrojasmone (3-methyl-2-pentyl-2-cyclopenten-l-one) is prepared by the base-catalyzed aldol condensation of 2,5-undecanedione. 2,5-Undecanedione is itself prepared from heptanal and methyl vinyl ketone in the presence of thiazolium salts (329). cis-jasmone can be similarly prepared (330,331). 

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]. 

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