Total Synthesis of the Sex Pheromone of Clania variegata Snellen and Its Stereoisomers.

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.

Total synthesis of (6R,12R)-6,12-dimethylpentadecan-2-one, the sex pheromone of Diabrotica balteata LeConte.

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.

Asymmetric synthesis of the sex pheromone of the apple leafminer, Lyonetia prunifoliella.

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.

Asymmetric Synthesis of Contact Sex Pheromone of Tetropium fuscum and Its Enantiomer.

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.

Novel Ce-based coordination polymer nanoparticles with excellent oxidase mimic activity applied for colorimetric assay to organophosphorus pesticides.

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.

Asymmetric syntheses of four stereoisomers of 13-hydroxy-14-methylhexadecanoic acid as potential antibacterial agents.

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.

Synthesis of the enantiomers of 13-methylheptacosane, the sex pheromone of pear psylla, Cacopsylla pyricola.

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.

Cobalt-Bisoxazoline-Catalyzed Enantioselective Cross-Coupling of α-Bromo Esters with Alkenyl Grignard Reagents.

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.

Enantioselective synthesis of (R)-Cinacalcet via cobalt-catalysed asymmetric Negishi cross-coupling.

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.

Cobalt-Catalyzed Enantioselective Negishi Cross-Coupling of Racemic α-Bromo Esters with Arylzincs.

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.

Synthesis of Chrysogeside B from Halotolerant Fungus Penicillium and Its Antimicrobial Activities Evaluation.

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.

[Enantioseparation of 2-phenylcarboxylic acid esters by capillary gas chromatography].

Chiral 2-arylcarboxylic acid derivatives are important intermediates for preparing 2-arylcarboxylic acids, which are non-steroidal anti-inflammatory drugs (NSAIDs). In order to separate 2-phenylcarboxylic acid ester enantiomers by capillary gas chromatography (CGC), 2, 6-di-O-pentyl-3-O-butyryl-ß-cyclodextrin and 2,6-di-O-benzyl-3-O-heptanoyl-ß-cyclodextrin were used as CGC chiral stationary phases, separately, and their enantioseparation abilities to enantiomers of methyl 2-phenylbutanoate, ethyl 2-phenylbutanoate, isopropyl 2-phenylbutanoate, methyl 2-phenylpropionate and cyclopentyl 2-phenylpropionate were examined. It was found that methyl 2-phenylbutanoate, methyl 2-phenylpropionate and cyclopentyl 2-phenylpropionate were successfully separated by using 2,6-di-O-pentyl-3-O-butyryl-ß-cyclodextrin and 2,6-di-O-benzyl-3-O-heptanoyl-ß-cyclodextrin as CGC chiral stationary phases, respectively. The enantiomer separation abilities of 2, 6-di-O-pentyl-3-O-butyryl-ß-cyclodextrin to the three pairs of 2-phenylcarboxylic acid esters tested are superior to those of 2, 6-di-O-benzyl-3-O-heptanoyl-ß-cyclodextrin.

Total Syntheses of (R)-Strongylodiols C and D.

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.

Cobalt-bisoxazoline-catalyzed asymmetric Kumada cross-coupling of racemic α-bromo esters with aryl Grignard reagents.

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.

Highly enantioselective addition of phenylethynylzinc to aldehydes catalyzed by chiral cyclopropane-based amino alcohols.

The enantioselective addition of phenylethynylzinc to aldehydes catalyzed by a series of cyclopropane-based amino alcohol ligands 7 was investigated. The reactions afforded chiral propargylic alcohols in high yields (up to 96%) and with excellent enantioselectivities (up to 98% ee) under mild conditions. Furthermore, studies on the structural relationship show that the matching of the chiral center configuration is crucial to obtain the high enantioselectivity.

Highly enantioselective addition of 1,3-diynes to aldehydes catalyzed by a zinc-amino alcohol complex.

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).

Highly enantioselective zinc/amino alcohol-catalyzed alkynylation of aldehydes.

Meeting the challenge: The zinc/amino alcohol catalyzed enantioselective addition of terminal alkynes to aldehydes is effective with both phenylacetylene and methyl propiolate, leading to chiral secondary propargyl alcohols with very high enantioselectivity (see scheme).