79517-78-5Relevant academic research and scientific papers
Synthesis of all the stereoisomers of 6-methyl-2-octadecanone, 6,14-dimethyl-2-octadecanone, and 14-methyl-2-octadecanone, the components of the female-produced sex pheromone of a moth, Lyclene dharma dharma
Mori, Kenji
scheme or table, p. 2798 - 2805 (2009/08/15)
All of the stereoisomers of the components of the female-produced sex pheromone of a moth, Lyclene dharma dharma, were synthesized. They are (R)- and (S)-6-methyl-2-octadecanone, (6R,14R)-, (6R,14S)-, (6S,14R)-, and (6S,14S)-6,14-dimethyl-2-octadecanone, and (R)- and (S)-14-methyl-2-octadecanone. Enantiomers of citronellal and methyl (S)-3-hydroxy-2-methylpropanoate were the starting materials, and olefin cross metathesis was employed as the key reaction.
Putative Diels-Alder-catalyzed cyclization during the biosynthesis of lovastatin
Witter, David J.,Vederas, John C.
, p. 2613 - 2623 (2007/10/03)
A Diels-Alder cyclization proposed to occur during polyketide synthase assembly of the bicyclic core of lovastatin (1) (mevinolin) by Aspergillus terreus MF 4845 was examined via the synthesis of the N-acetylcysteamine (NAC) thioester of [2,11-13C2]-(E,E,E)-(R)-6-methyldodecatri-2,8,10-enoate (5a). In vitro Diels-Alder cyclization of the corresponding unlabeled NAC ester 5b, ethyl ester 18b, and acid 20b yielded two analogous diastereomers in each case, under either thermal or Lewis acid-catalyzed conditions. The reaction of thioester 5 proceeds readily at 22°C in aqueous media. For 18b, one product is trans-fused ethyl (1R,2R,4aS, 6R,8aR)-1,2,4a,5,6,7,8,8a-octahydro-2,6-dimethylnaphthalene-1-carboxyl ate (30) (endo product), and the other is cis-fused ethyl (1R,2S,4aR,6R,8aR)-1,2,4a,5,6,7,8,8a-octahydro-2,6-dimethylnaphthalene -1-carboxylate (31) (exo product). Isomer 21 with stereochemistry analogous to 4a,5-dihydromonacolin L (2), a precursor of 1, was made by transformation of a tricyclic lactone, (1S,2S,4aR,6S,8S,8aS)-1-(ethoxycarbonyl)-1,2,4a,5,6,7,8,8a-octahydro-2 -methyl-6,8-naphthalenecarbolactone (22) using reduction and Barton deoxygenation. Comparison of 21 with 30 and 31 confirmed the structural assignments and showed that the nonenzymatic 4 + 2 cyclizations of 5, 18, and 20 proceed via chairlike exo and endo transition states with the methyl substituent pseudoequatorial. The proposed biosynthetic Diels-Alder leading to lovastatin (1) would require an endo conformation with the methyl substituent pseudoaxial. Intact incorporation of the labeled hexaketide triene 5a into 1 was not achieved because of rapid degradation by A. terreus cells.
ENANTIO-CONTROLLED SYNTHESIS OF THE MACROCYCLIC C14-C23 SUBUNIT OF CYTOCHALASIN B
Thijs, L.,Stokkingreef, E. H. M.,Lemmens, J. M.,Zwanenburg, B.
, p. 2949 - 2956 (2007/10/02)
The synthesis of the C14-C23 macrocyclic subunit of cytochalasin B from pulegone is described.The key feature of this synthesis is the photo-induced rearrangement of epoxy diazomethyl ketone E to a γ-hydroxy alkenoic ester (Scheme 2).The intermediate epoxy alcohol F was prepared using the asymmetric Sharpless epoxidation.Considerable attention was given to the preparation of allylic alcohol 14, having a t-butyldimethylsilyloxy protecting function, as starting material for the asymmetric epoxidation, however, several unforeseen difficulties were encountered (Schemes 3 and 4).Satisfactory results were obtained using the methoxy group as protecting function (Scheme 5).The allylic alcohol 22 was prepared from bromide 20 by chain lengthening with propargyl alcohol.The Sharpless epoxidation of 22 took place with high induction.Conversion to epoxy ester 24, to diazo ketone 25 and photo-rearrangement to 26 and deprotection to give 28, completes the sequence.
Synthesis of (R)-(-)-10-Methyl-2-tridecanone, the Pheromone of the Southern Corn Rootworm
Senda, Shuji,Mori, Kenji
, p. 795 - 798 (2007/10/02)
(R)-(-)-10-Methyl-2-tridecanone, the pheromone of Diabrotica undecimpunctata howardi Barber, was synthesized from (R)-(+)-citronellyl acetate.
