• Bulletin of the Korean Chemical Society
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• v.12 no.4
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• pp.392-397
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• 1991

A stereocontrolled synthesis of (${\pm}$)-isocomene (1) via selective monoketalization of tricyclo[6.3.0.$0^{1.5}$]undeca-4,7-dione(13) was reported. Grignard reaction of bicyclic enone 10, which was prepared from 2-methyl-1,3-cyclopentadione, gave the 1,4-addition product 11. The subsequent aldol condensation product 12 was converted to mesyl derivative 13. Transformation from 13 to the desired product 19 was achieved by a series of reactions, i.e., the selective monoketalization at C-4 carbonyl group, the elimination of a mesyl group, Birch alkylation, methylation at C-6, the reduction of carbonyl group, the dehydration of alcohol 18, and hydrolysis of the ketal group.

• Journal of the Korean Applied Science and Technology
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• v.15 no.4
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• pp.35-44
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• 1998

All the triacylglycerols including the molecular species having ${\Delta}^5$-unsaturated fatty acids from the seeds of Pinus Koraiensis, were split into a mixture of diacylglycerols by a Grignard reagent prepared with allyl bromide without arousing acyl chains of a glycerol moiety to migration, and were also easily partially hydrolyzed to diacylglycerols by pancreatic lipase. (S)-(+)-(1-naphthyl)ethyl urethane(NEU) derivatives of the diacylglycerol mixture derived from the triacylglycerols were fractionated into sn-1, 3-, sn-1, 2- and sn-2, 3-DG-NEU by silica-HPLC and the fatty acid composition of these fractions was analysed. $C_{18:1{\omega}9}$ is distributed evenly in the three positions of TG with $C_{18:2{\omega}6}$ mainly located in sn-2 position, while ${\Delta}^5$-unsaturated fatty acids such as ${\Delta}^{5.9}-C_{18:2}$, ${\Delta}^{5.9.12}-C_{18:3}$ and ${\Delta}^{5.11.14}-C_{20:3}$ are exclusively present in the sn-3 position. These results could be confirmed by $^{13}C$-NMR spectroscopy : the signals at $^{\delta}$173.231 ppm and $^{\delta}$172.811 ppm of the carbonyl carbon of acyl moieties indicate the presence of saturated acids and/or $C_{18:1{\omega}9}$ (oleic acid) in the ${\alpha}({\alpha}')$- or ${\beta}$- positions, and $C_{18:2{\omega}6}$ including $C_{18:1{\omega}9}$ in the ${\beta}$-position, respectively. In addition, the resonance at $^{\delta}$173.044 ppm suggested a location of ${\Delta}^5$-unsaturated fatty acid moiety in the ${\alpha}({\alpha}')$-position.