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1.
Kenji Mori 《Tetrahedron》2018,74(13):1444-1448
The racemate and the enantiomers of (E)-cis-6,7-epoxy-2-nonenal, the male pheromone of Aromia bungii, were synthesized by olefin cross metathesis between crotonaldehyde and (±)-, (+)- and (?)-cis-3,4-epoxy-7-octene. The epoxide was prepared by the Grignard coupling between allylmagnesium bromide and (±)-, (+)- and (?)-cis-2,3-epoxypentyl triflate. (±)-cis-2,3-Epoxy-1-pentanol was prepared by MCPBA epoxidation of (Z)-2-penten-1-ol, while its enantiomers were synthesized by the Sharpless asymmetric epoxidation of the allylic alcohol.  相似文献   

2.
Both enantiomers of methyl (E)-2,4,5,-tetradecatrienoate were synthesized with 125–127% the rotatory power of the natural product which was isolated as the pheromone of Acanthoscelides obtectus. The absolute configuration of the levorotatory natural pheromone was confirmed to be R.  相似文献   

3.
All the eight stereoisomers of 3-acetoxy-11,19-octacosadien-1-ol (1), the male sex pheromone (CH503) of Drosophila melanogaster, were synthesized from two acetylenic starting materials and the enantiomers of 3,4-epoxy-1-butanol PMB ether. Complete separation of the eight isomers of 1 by reversed phase HPLC at ?20 °C was achieved after their esterification with (1R,2R)-2-(2,3-anthracenedicarboximido)cyclohexanecarboxylic acid (27), and the natural CH503 was found to be (3R,11Z,19Z)-1.  相似文献   

4.
《Tetrahedron: Asymmetry》2003,14(13):1951-1954
The practical preparation of enantiomerically pure (E)-4-(tributylstannanyl)but-3-en-2-ol 1 from 3-butyn-2-ol 2 is reported. A modified Guibé's Pd-catalyzed hydrostannation of 2 provided the racemic γ-hydroxy vinylstannane 1 in a good yield. The enzymatic esterification of 1, with an inexpensive lipozyme, afforded (R)-3 and (S)-1 with very high enantiomeric excesses and chemical yields. This procedure is suitable for the multigram scale preparation of the potential chiral building blocks, (R)-1 and (S)-1.  相似文献   

5.
《Tetrahedron: Asymmetry》2007,18(4):527-536
The natural fragrances (+)-trans whisky lactone 2 and (+)-trans cognac lactone 4, together with a minor amount of their (−)-cis stereoisomers, were prepared in 50% and 42% overall yield, respectively, starting from racemic 1-hepten-3-ol (±)-5 and 1-octen-3-ol (±)-6. The procedure involved first the enantioconvergent, lipase mediated transformation of the secondary allylic alcohols derived dichloroacetates (±)-7 and (±)-8 into the corresponding homochiral (+)-7 and (+)-8, combined with their cyclization under a transition metal catalyzed atom transfer process.  相似文献   

6.
Tetrahydroisoquinoline alkaloids, (S)-(−)-trolline, (R)-(+)-crispin A, and (R)-(+)-oleracein E, have been synthesized stereoselectively from the both enantiomers of common intermediate (S)-4 and (R)-4. The key step in the synthesis include a stereoselective Bi(OTf)3-catalyzed intramolecular 1,3-chirality transfer reaction of chiral non-racemic amino allylic alcohols (S)-6 and (R)-6 to construct both enantiomers of (E)-1-propenyl tetrahydroisoquinoline 4.  相似文献   

7.
(±)-7-Deoxy-4-demethoxydaunomycinone((±)-3) was found to be cleanly resolved by forming a mixture of the diastereomereic acetals((-)-9and(+)-10 or(+)-9 and(-)-10)with the title vicinal-diol(+)-or ( )-5), affording optically pure (R)-( )-3. The resolving agents (( + )- and ( )-5) were readily synthesized from unnatural(2S,3S)-(-)-tartaric acid((-)-6)or D-(-)-mannitol and natural (2R,3R)-(+)-tartaric acid((+)6), respectively. The undesired enantiomer ((S)-(+ )-3) obtained by the optical resolution could be racemized by heating with trifluoromethanesulfonic acid in aq acetic acid. Optically pure (R)-3 was elaborated to optically pure (+)-4-demethoxydaunomycinone ((+)-2b) and (+)-demethoxyadriamycinone ((+)-2a) by featuring highly stereoselective ( ? 20:1) introduction of the OH group into the C7-position as a key step.  相似文献   

8.
《Tetrahedron: Asymmetry》2004,15(3):457-463
An efficient synthesis of both enantiomers of dimethyl δ-amino-β-hydroxyethylphosphonate 6 has been achieved starting from anthranilic acid, through the resolution of dimethyl (±)-2-(2-N,N-dibenzylaminophenyl)-2-hydroxyethylphosphonate 9 with (S)-O-methylmandelic acid. The absolute configuration of the enantiomers 9 was assigned by the Dale and Mosher approach using the extended Newman projections and molecular mechanics.  相似文献   

9.
New ligand (E)-4-((dimethylamino)methyl)-2-((4,5-dimethylthiazol-2-yl)diazenyl)phenol (HDmazo) was prepared by the coupling reaction between 4,5-dimethylthiazol-2-amine and 4-((dimethylamino)methyl)phenol. Moreover, the [MCl2(HDmazo)] and [M(HDmazo)2] [MII = Pd and Pt] were prepared using the direct reaction of equivalent molar of HDmazo and Na2PdCl4 or K2PtCl4. The HDmazo and its complexes were investigated by different spectroscopic techniques. In complexes (12) HDmazo ligand behaves as bidentate style through the nitrogen of azo group and nitrogen of thiazole ring towards Pd(II) and Pt(II). Or in a bidentate fashion via the oxygen atom of the hydroxylate group and nitrogen atom of azo group as mono-anion in complexes (34). Further, the study of biological activity against four pathogenic bacteria showed that compound (3) exhibited good activity compared to other compounds. Additional the anti-tumor action against A2870 cell lines was screened, and the complexes (1) and (2) displayed good activity with 7.45 ± 0.98 µM and 13.23 ± 1.43 µM, respectively. The binding mechanism of the prepared compounds with EGFR tyrosine kinase, was investigated using molecular docking experiments.  相似文献   

10.
《Tetrahedron: Asymmetry》2007,18(14):1712-1720
Enantioselective acylation of some (±)-3-alkyl-3-phenyl-1-propanols was performed with enzymes as catalysts. Moderate enantiomeric ratios (E), ranging up to E = 11.6, were obtained. In the resolution, some of the lipases selectively acylated the (+)-enantiomer while others acylated the (−)-enantiomer of the γ-substituted primary alcohols 14. Thus, it is possible to obtain both enantiomers of the alcohols as remaining substrate with high enantiomeric purity. The resolution of (±)-4,4-dimethyl-3-phenyl-1-pentanol 4 was extensively studied and screening experiments were conducted to select suitable lipase(s), reaction medium, acyl donor and appropriate temperature combinations to increase the enantiomeric ratio. Chirazyme® L-6/chloroform/vinyl propionate/38 °C and Chirazyme® L-7/di-iso-propyl ether/vinyl propionate/0 °C were chosen to obtain both enantiomers, (R)-(+)-4 and (S)-(−)-4, respectively, via sequential resolutions in excellent enantiomeric excess (>98%) and in 25% and 22% yield, respectively.  相似文献   

11.
《Tetrahedron: Asymmetry》2007,18(1):101-107
Different lipases were screened as biocatalysts in the kinetic resolution process of (±)-hept-1-en-3-ol 1, (±)-5-methylhex-1-en-3-ol 2, (±)-6-methylhept-2-en-4-ol 3, (±)-6,6-dimethylhept-2-en-4-ol 4, and 1-phenylbut-3-en-2-ol 5 by enantioselective transesterification. The acylation of (±)-1 and (±)-2 catalyzed by Novozym 435 (Candida antarctica) was very effective and proceeded with good enantioselectivity. After 4–8 h of reactions the esters formed and the alcohols, which remained were obtained with high enantiomeric excess with 97–100% ee and 91–100% ee, respectively. The lipase Amano PS (Burkholderia cepacia) was the best catalyst in the asymmetric transesterification of (±)-5 affording the (R)-alcohol with 90–95% ee and the (S)-ester with 98–100% ee. Low enantioselectivities were observed in the cases of lipase-catalyzed acylation of (±)-3 and (±)-4.  相似文献   

12.
Wittig reaction of (E)-3-(3-guaiazulenyl)propenal (11) with (3-guaiazulenylmethyl)triphenylphosphonium bromide (9) in ethanol containing NaOEt at 25 °C for 24 h under argon gives the title new (2E,4E)-1,3-butadiene derivative 4, in 33% isolated yield, which upon treatment with hexafluorophosphoric acid (i.e., 65% HPF6 aqueous solution) in tetrahydrofuran (=THF) at 25 °C for 1 h under aerobic conditions affords a new air (two-electron) oxidation product (E)-ethylene-1,2-bis(3-guaiazulenylmethylium) bis(hexafluorophosphate) (14), quantitatively, and further, zinc-reduction of 14 in trifluoroacetic acid (=CF3COOH) at 0 °C for 1 h under argon reverts 4, quantitatively. Along with the above interesting results, our discovered another preparation method, spectroscopic properties, crystal structure, and electrochemical behavior of 4, which serves as a strong two-electron donor and acceptor, compared with those of the previously reported (E)-1,2-di(3-guaiazulenyl)ethylene (3) are documented in detail.  相似文献   

13.
Both enantiomers of (3Z,9Z)-cis-6,7-epoxy-3,9-octadecadiene, one of which is the major component of the sex pheromone of Ectropis oblique Prout, were synthesized in 23% overall yield for the (?)-(6S,7R)-enantiomer and 18% yield for the (+)-(6R,7S)-isomer. This protocol uses a sequential regioselective ring-opening strategy and provides a convenient and reliable access to other structurally related insect sex pheromones. Preliminary biological studies revealed that (?)-(6S,7R)-2a was roughly as active as the natural pheromone, while racemic (±)-2 was less bioactive and (+)-2b was much less bioactive.  相似文献   

14.
Readily available methyl hydrogen (R)-3-methylglutarate(2) is a useful chiral building block for the synthesis of several biologically active compounds. Enantiomerically pure (R)-2 has been employed to synthesize stereospecifically each of the two enantiomers, 1a and 1b, of 10-methyl-2-tridecanone, the sex pheromone of the southern corn rootworm, Diabrotica undecimpunctata howardi Barber. Compound (R)-2 has been also used to prepare 99% optically pure (R)-3-methyl-1-pentanol (6) and enantiomerically pure (R)-5-methyl-i-tricosyne (7). These compounds are useful building blocks suitable for the further elaboration to other chiral insect pheromones.  相似文献   

15.
《中国化学快报》2022,33(7):3543-3548
Racemic [18F]FBFP ([18F]1) proved to be a potent σ1 receptor radiotracer with superior imaging properties. The pure enantiomers of unlabeled compounds (S)- and (R)-1 and the corresponding iodonium ylide precursors were synthesized and characterized. The two enantiomers (S)-1 and (R)-1 exhibited comparable high affinity for σ1 receptors and selectivity over σ2 receptors. The Ca2+ fluorescence assay indicated that (R)-1 behaved as an antagonist and (S)-1 as an agonist for σ1 receptors. The 18F-labeled enantiomers (S)- and (R)-[18F]1 were obtained in >99% enantiomeric purity from the corresponding enantiopure iodonium ylide precursors with radiochemical yield of 24.4% ± 2.6% and molar activity of 86–214 GBq/µmol. In ICR mice both (S)- and (R)-[18F]1 displayed comparable high brain uptake, brain-to-blood ratio, in vivo stability and binding specificity in the brain and peripheral organs. In micro-positron emission tomography (PET) imaging studies in rats, (S)-[18F]1 exhibited faster clearance from the brain than (R)-[18F]1, indicating different brain kinetics of the two enantiomers. Both (S)- and (R)-[18F]1 warrant further evaluation in primates to translate a single enantiomer with more suitable kinetics for imaging the σ1 receptors in humans.  相似文献   

16.
《Tetrahedron: Asymmetry》2006,17(14):2133-2142
(S)-Perillyl alcohol was converted to (R)-cryptone (91.5–93% ee) in six steps, which was then treated with methyllithium to give (1S,4R)-4-isopropyl-1-methyl-2-cyclohexen-1-ol, the aggregation pheromone of the ambrosia beetle Platypus quercivorus. The racemic pheromone was also prepared by methylation of (±)-cryptone. Both (1R,4R)- and (1S,4S)-isomers (98% ee) of the pheromone were synthesized from the enantiomers of dihydrolimonene oxide.  相似文献   

17.
(2S,3R,4E,6R)-N-(30-Hydroxytriacontanoyl)-6-hydroxy-4-sphingenine (1) and its (6S)-isomer (1′) were synthesized by starting from pentadecan-15-olide, the enantiomers of 1-pentadecyn-3-ol, and (S)-Garner's aldehyde. Comparison of the 1H NMR spectra of the tetraacetyl derivatives of 1 and 1′ with that of ceramide B, a new protein-bound ceramide in human stratum corneum, revealed it to be (2S,3R,4E,6R)-1.  相似文献   

18.
The total synthesis of methyl β-d-vicenisaminide 1 has been achieved. In this approach, the synthesis of enantiomerically pure methyl (4R,5S)- and (4S,5R)-4-azido-5-hydroxy-2(E)-hexenoates 2 was established by enzymatic resolution of (±)-anti-5-acetoxy -4-azido-2(E)-hexenoate 4. Another stereogenic center was introduced by base-catalyzed intramolecular conjugate addition of a hemiacetal-derived alkoxide nucleophile obtained by the reaction of methyl (4S,5R)-N-4-tert-butoxycarbonyl-N-methylamino-5-hydroxyl-2(E)-hexenoate 8 and benzaldehyde in the presence of a base.  相似文献   

19.
《Tetrahedron: Asymmetry》2000,11(8):1691-1695
Formal synthesis of chiral grandisol and the oleander scale pheromone and their antipodes can be achieved through a convenient lipase-catalyzed enantiodifferentiation process of the common cyclobutane intermediate (±)-2-(1-hydroxyethyl)-1-(methoxymethyloxyethyl)cyclobutane-1-carbonitrile 3. The resolution afforded both enantiomers in almost enantiomerically pure form and their absolute configurations were assigned on the basis of the Δδ values for their (R)- and (S)-MTPA esters.  相似文献   

20.
Highly optically pure enantiomers of (E)-6-isopropyl-3,9-dimethyl-5,8-decadienyl acetate, the sex pheromone of the yellow scale (Aniodiella citrina), were stereoselectively from synthesized from(R)-(+)-citronellic acid. Only the (s)-enantiomer was bioactive.  相似文献   

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