RESUMO
The Lichen moth, Lyclene dharma dharma (Arctiidae, Lithosiinae), plays a significant role in forest ecosystem dynamics. A concise and novel method to synthesize the active sex pheromone components, (S)-14-methyloctadecan-2-one ((S)-1), (S)-6-methyloctadecan-2-one ((S)-2), and their enantiomers has been developed. Key steps in the synthesis include the use of Evans' chiral auxiliaries, Grignard cross-coupling reactions, hydroboration-oxidation, and Wacker oxidation. The synthesized sex pheromone components hold potential value for studies on communication mechanisms, species identification, and ecological management.
Assuntos
Mariposas , Atrativos Sexuais , Atrativos Sexuais/química , Atrativos Sexuais/síntese química , Animais , Estereoisomerismo , Feminino , Estrutura MolecularRESUMO
The paulownia bagworm, Clania variegata Snell, is an economically important pest of agriculture and forests. The sex pheromone of this pest and its stereoisomers were synthesized, and two of the stereoisomers were prepared for the first time. Our strategy was efficient and mainly included the ring-opening reaction of (S)-2-methyloxirane, the coupling of chiral sulfonate, the oxidative cleavage of olefin, and Yamaguchi esterification. Moreover, the overall yields of our synthesis were 23-29%, with eight steps in the longest route.
Assuntos
Atrativos Sexuais , Atrativos Sexuais/síntese química , Atrativos Sexuais/química , Estereoisomerismo , AnimaisRESUMO
A concise synthesis of the sex pheromones of elm spanworm as well as painted apple moth has been achieved. The key steps were the alkylation of acetylide ion, Sharpless asymmetric epoxidation and Brown's P2-Ni reduction. This approach provided the sex pheromone of the elm spanworm (1) in 31% total yield and those of the painted apple moth (2, 3) in 26% and 32% total yields. The ee values of three final products were up to 99%. The synthesized pheromones hold promising potential for use in the management and control of these pests.
Assuntos
Compostos de Epóxi , Mariposas , Atrativos Sexuais , Animais , Atrativos Sexuais/síntese química , Atrativos Sexuais/química , Compostos de Epóxi/química , Estrutura MolecularRESUMO
Diabrotica balteata LeConte is one of the most important polyphagous agricultural pests. The sex pheromone of this pest was synthesized using Evans asymmetric alkylation, ring-opening reaction of (R)-2-methyloxirane, SN 2 alkylation of secondary tosylate, and coupling of chiral tosylate with Grignard reagent as central strategies. The sex pheromone prepared herein would be useful to control D. balteata.
Assuntos
Besouros , Atrativos Sexuais , Animais , Estereoisomerismo , AlquilaçãoRESUMO
Lyonetia prunifoliella is a significant pest in orchards and damages apple. The sex pheromones of this pest were prepared via a new and concise method. The central to our method were Evans' chiral auxiliaries, the addition of chiral Grignard reagent to aldehyde and Wittig coupling.
Assuntos
Malus , Mariposas , Atrativos Sexuais , Animais , Estereoisomerismo , Aldeídos , FeromôniosRESUMO
Tetropium fuscum is a harmful forest pest and attacks spruces. The contact sex pheromone of this pest, (S)-11-methyl-heptacosane, and its enantiomer were synthesized via Evans' chiral auxiliaries. The key steps of this approach included acylation of carboxylic acid, diastereoselective methylation of oxazolidinone amide, and Wittig coupling of the aldehyde with chiral phosphonium salt. The synthetic pheromones would have potential utility in the control of this pest.
Assuntos
Besouros , Atrativos Sexuais , Animais , Feromônios , Aldeídos , Ácidos Carboxílicos , AmidasRESUMO
Cerium, as a lanthanide, has attracted considerable interest because of its excellent catalytic activity. Here, we propose a novel cerium-based coordination polymer nanoparticles named DPA-Ce-GMP, which have excellent oxidase-mimicking properties. Furthermore, a colorimetric probe that can act as an inhibitor to suppress the activity of acetylcholinesterase (AChE) was developed for detecting organophosphorus pesticides (OPs). DPA-Ce-GMP catalyzes colorless 3,3',5,5'-tetramethylbenzidine (TMB) to produce a blue color, and AChE catalyzes acetylthiocholine to produce thiocholine (TCh), which can weaken DPA-Ce-GMP-catalyzed TMB. After the addition of OPs, the enzymatic activity of AChE was inhibited to produce less amount of TCh, resulting in more DPA-Ce-GMP-catalyst oxidized TMB to show an increasing blue color. Dichlorvos, as the samples, with the limit of 0.024 µg/L. Overall, we believe that the colorimetric probe can be used for the rapid, low-cost, and large-scale field detection of OPs in food samples.
Assuntos
Técnicas Biossensoriais , Cério , Nanopartículas , Praguicidas , Acetilcolinesterase , Técnicas Biossensoriais/métodos , Colorimetria/métodos , Compostos Organofosforados , Oxirredutases , Praguicidas/análise , PolímerosRESUMO
The first total syntheses of four stereoisomers of 13-hydroxy-14-methylhexadecanoic acid have been accomplished. Central to this strategy are asymmetric alkynylation of aldehyde, acid-catalyzed lactonization, the selective protection of primary alcohol and Wittig reaction. The product 1a was obtained in 17 steps in 2% overall yield. Moreover, these synthetic chiral hydroxy fatty acids 1a-1d are valuable for the development of antibacterial agents.
Assuntos
Antibacterianos , Hidroxiácidos , Álcoois , Antibacterianos/farmacologia , Ácidos Palmíticos , EstereoisomerismoRESUMO
An efficient and gram-scale enantioselective synthesis of (R)- and (S)-13-methylheptacosane, the sex pheromone of pear psylla, has been developed. The key steps of the approach included Evans' chiral auxiliaries and Wittig coupling of chiral phosphonium salt with aldehyde.
RESUMO
The first catalytic asymmetric Kumada cross-coupling of organic halides with alkenyl Grignard reagents has been developed. The reaction was promoted by the cobalt-bisoxazoline catalyst and afforded various α-alkyl-ß,γ-unsaturated esters with excellent enantioselectivities and moderate to good yields (≤95% ee and ≤82% yields). The formal synthesis of the California red scale pheromone using this method was investigated, and radical clock experiments were performed.
RESUMO
A novel enantioselective synthesis of (R)-cinacalcet with 99% enantiomeric excesses (ee) has been achieved. The main strategies of the approach include a gram-scale cobalt-catalysed asymmetric cross-coupling of racemic ester with arylzinc reagent, Hoffman-type rearrangement of acidamide, the amidation of chiral amine, and improving the ee of chiral amide from 87% to 99% via recrystallization.
RESUMO
The first cobalt-catalyzed enantioselective Negishi cross-coupling reaction, and the first arylation of α-halo esters with arylzinc halides, are disclosed. Employing a cobalt-bisoxazoline catalyst, various α-arylalkanoic esters were synthesized in excellent enantioselectivities and yields (up to 97 % ee and 98 % yield). A diverse range of functional groups, including ether, halide, thioether, silyl, amine, ester, acetal, amide, olefin and heteroaromatics is tolerated by this method. This method was suitable for gram-scale reactions, enabling the synthesis of (R)-xanthorrhizol with high enantiopurity. Radical clock experiments support the intermediacy of radicals.
RESUMO
Chrysogeside B, a natural cerebroside, was efficiently synthesized from commercial feedstocks. The bioassays showed that compounds 4, 5 and 6 exhibited enhanced biological activities compared Chrysogeside B. Further studies revealed that free hydroxyl groups and glycosidic bond have significant impact on the antimicrobial activities. The synthesis of Chrysogeside B and analogues designed to allow identification of the features of this glycolipid required for recognition by tested bacteria and Hela cells is described.
Assuntos
Anti-Infecciosos/química , Anti-Infecciosos/farmacologia , Cerebrosídeos/química , Penicillium/química , Anti-Infecciosos/síntese química , Sobrevivência Celular/efeitos dos fármacos , Cerebrosídeos/síntese química , Enterobacter aerogenes/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Células HeLa , Humanos , Testes de Sensibilidade Microbiana , Modelos Químicos , Estrutura MolecularRESUMO
The first total syntheses of two marine natural products, (R)-strongylodiols C and D, with 99% ee were achieved. The key steps of the strategy include the zipper reaction of an alkyne, the asymmetric alkynylation of an unsaturated aliphatic aldehyde catalyzed with Trost's ProPhenol ligand, and the Cadiot-Chodkiewicz cross-coupling reaction of a chiral propargylic alcohol with a bromoalkyne.
Assuntos
Álcoois/síntese química , Alcinos/síntese química , Produtos Biológicos/síntese química , Álcoois/química , Alcinos/química , Produtos Biológicos/química , Catálise , Ligantes , Estrutura Molecular , Propanóis/química , EstereoisomerismoRESUMO
The first cobalt-catalyzed asymmetric Kumada cross-coupling with high enantioselectivity has been developed. The reaction affords a unique strategy for the enantioselective arylation of α-bromo esters catalyzed by a cobalt-bisoxazoline complex. A variety of chiral α-arylalkanoic esters were prepared in excellent enantioselectivity and yield (up to 97% ee and 96% yield). The arylated products were transformed into α-arylcarboxylic acids and primary alcohols without erosion of ee. The new enantioenriched α-arylpropionic esters synthesized herein are potentially useful in the development of nonsteroidal anti-inflammatory drugs. This method was conducted on gram-scale and applied to the synthesis of highly enantioenriched (S)-fenoprofen and (S)-ar-turmerone.
RESUMO
Asymmetric catalysis: A highly enantioselective and efficient procedure for the amino alcohol-zinc-catalyzed addition of 1,3-diynes to various aromatic, α,ß-unsaturated, and aliphatic aldehydes has been developed. The present catalytic system was successfully applied in the concise synthesis of natural products such as (S)-strongylodiols A and B (see scheme).
Assuntos
Aldeídos/química , Amino Álcoois/química , Di-Inos/química , Compostos Organometálicos/química , Zinco/química , Catálise , Estrutura Molecular , EstereoisomerismoRESUMO
Phosphine-catalyzed [3+2] and [4+3]annulation reactions of C,N-cyclic azomethine imines with allenoates have been developed to give a variety of pharmaceutically attractive tetrahydroisoquinoline derivatives in moderate to excellent yields. The two distinct reaction pathways, [3+2] and [4+3]cyclization, depend on the nature of the nucleophilic phosphine and the allenoate. Generally, for α-alkylallenoates, the reactions always proceed with [3 +2]cyclization as the major pathway no matter what phosphine was used; for α-ArCH2-substituted allenoates, the reaction pathway was controlled by the phosphine catalyst used.
RESUMO
In this paper we describe the phosphine-catalyzed [3 + 2], [3 + 3], [4 + 3], and [3 + 2 + 3] annulations of azomethine imines and allenoates. These processes mark the first use of azomethine imines in nucleophilic phosphine catalysis, producing dinitrogen-fused heterocycles, including tetrahydropyrazolo-pyrazolones, -pyridazinones, -diazepinones, and -diazocinones. Counting the two different reaction modes in the [3 + 3] cyclizations, there are five distinct reaction pathways-the choice of which depends on the structure and chemical properties of the allenoate. All reactions are operationally simple and proceed smoothly under mild reaction conditions, affording a broad range of 1,2-dinitrogen-containing heterocycles in moderate to excellent yields. A zwitterionic intermediate formed from a phosphine and two molecules of ethyl 2,3-butadienoate acted as a 1,5-dipole in the annulations of azomethine imines, leading to the [3 + 2 + 3] tetrahydropyrazolo-diazocinone products. The incorporation of two molecules of an allenoate into an eight-membered-ring product represents a new application of this versatile class of molecules in nucleophilic phosphine catalysis. The salient features of this protocol--the facile access to a diverse range of nitrogen-containing heterocycles and the simple preparation of azomethine imine substrates--suggest that it might find extensive applications in heterocycle synthesis.
Assuntos
Compostos Azo/química , Iminas/química , Fosfinas/química , Tiossemicarbazonas/química , Alcadienos/química , CatáliseRESUMO
A new chiral stationary phase for gas chromatography, heptakis (2, 3, 6-tri-O-methoxymethyl)-beta-cyclodextrin, was synthesized by substituting the 2,3,6-OH groups of beta-cyclodextrin with methoxymethyl groups, and a coated capillary column for gas chromatography was made by coating this new stationary phase with static method. The chromatographic properties and separation abilities of the prepared stationary phase were studied. The test results showed that it possessed good separation abilities to Grob test mixture, disubstituted benzene isomers (e. g. nitrotoluenes, bromotoluenes, dichlorobenzenes, dimethylbenzenes) and some chiral compounds such as methyl 2-hydroxypropionates, ethyl 2-hydroxypropionates, methyl 2-methylsulfonylpropionates. The comparison of chiral separation results between 2,3,6-tri-O-methoxymethyl-beta-cyclodextrin and 2,3,6-tri-O-methyl-beta-cyclodextrin showed that the separation abilities of the two stationary phases were different and complementary to each other for some chiral ester enantiomers.