- Enantioselective synthesis of the essential oil and pheromonal component ar-himachalene by a chiral pool and chirality induction approach
-
The enantioselective synthesis of both isomers of ar-himachalene has been achieved starting from enantiomerically pure citronellal and p-methyl α-methyl styrene as an application of a chiral pool and chirality induction approach, respectively. The key reactions involved in the synthesis include the Sharpless asymmetric dihydroxylation for the induction of chirality at benzylic carbon bearing the methyl group and the use of a hypervalent iodine reagent or trimethylsilyldiazomethane (TMSCHN2) for the six to seven membered ring expansion.
- Chavan, Subhash P.,Khatod, Harshali S.
-
p. 1410 - 1415,6
(2020/09/16)
-
- Synthesis and stereochemistry of the four himachalene-type sesquiterpenes isolated from the flea beetle (Aphthona flava) as pheromone candidates
-
Both the (1S,2R) and (1R,2S) isomers of 2,6,6-trimethylbicyclo[5.4.0]undec- 7-en-9-one (1) were synthesized by starting from (S)- and (R)-citronellal (5), respectively. The stereochemistry of (1R,2S)-(-)-1 was established by an X-ray analysis; it exhibits a CD spectrum similar to that of cholest-4-en-3-one, in agreement with its absolute configuration. The ketones (1S,2R)- and (1R,2S)-1 were converted into the en-antiomers of three other himachalene hydrocarbons, 2,2,6-trimethyl-10-methylenebicyclo[5.4.0]undec-1(11)-ene (2), 1,1,5,8-tetramethyl-1,2,3,4,5,6,5a-hepta hydro benzo [1,2-a]-[7]annulene (3), and 1,1,5,8-tetramethyl-1,2,3,4,5-pentahydrobenzo[a][7]annulene (ar-himachalene, 4). The stereochemistry of these himachalene-type sesquiterpenes isolated from flea beetles such as Aphthona flava and Phyllotreta cruciferae as their male-pheromone components was revised to (1S,2R)-1, (6R,7S)-2,(5R,5aS)-3, and (R)-4. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Muto, Shin-Etsu,Bando, Masahiko,Mori, Kenji
-
p. 1946 - 1952
(2007/10/03)
-
- Five new cis-himachalane-type sesquiterpenes from the heartwood of Juniperus chinensis var. tsukusiensis
-
The following constituents were isolated from the heartwood of Juniperus chinensis vat. tsukusiensis: ar-himachalene (1), 2-himachalen-6-ol (2), 3- himachalen-6-ol (3), 2α,6α-epoxy-3-himachalene (4), 2α,6α- epoxyhimachalan-3β-ol (5), and chinensiol (6). Compounds 2-6 are new cis- himachalane-type sesquiterpenes, and their structures were elucidated on the basis of spectral and chemical evidence. Himachalane-type sesquiterpenes were isolated for the first time in Juniperus species.
- Shiu, Lung-Lin,Chen, Wen-Ching,Kuo, Yueh-Hsiung
-
p. 557 - 560
(2007/10/03)
-
- NEW SESQUITERPENOIDS FROM THE OLEORESIN OF Abies alba
-
The structures of four new sesquiterpenoids from the oleoresin of Abies alba have been studied, On the basis of various spectral characteristics, the structures of (10S, 11S)-himachala-2,4-diene, (10S, 11S)-himachala-3(12),4-diene, humula-4,9-dien-8-ol, and (4S, 5S, 10S)-selina-6-en-4-ol have been proposed for the compounds isolated.The stereochemistry of the assymetric centers was determined by the conversion of these compounds into known sesquiterpenes and also by analysis of PMR spectra with a shift reagent.
- Khan, V. A.,Tkachev, A. V.,Pentegova, V. A.
-
p. 606 - 611
(2007/10/02)
-