Design, Synthesis, and Anti-Fungal Evaluation of Heterocyclic Benzoxazole Derivatives.

In order to discover more promising anti-fungal agents, a series of benzoxazole family was synthesized by PPA-catalyzed condensation and a Raney nickel/hydrazine reduction. Altogether 45 compounds were obtained in good to excellent yields and characterized by FT-IR, NMR, MS, and X-ray crystal diffraction. Moreover, the biological activity against eight phytopathogenic fungi was investigated. All in all, most of these compounds bear moderate antifungal activities. Among them, three candidates show the strongest activities, compound 4ac, 4bc provided over 50% inhibition rate against five fungi. Especially, the inhibitory rate of compound 4ah on Mycosphaerella melonis reached 76.4%.

[Numerical study on the effect of the geometry size of multi-chamber infusion bag on its bursting force].

This study explored the variation of bursting force of multi-chamber infusion bag with different geometry size, providing guidance for its optimal design. Models of single-chamber infusion bag with different size were established. The finite element based on fluid cavity method was adopted to calculate the fluid-solid coupling deformation process of infusion bag to obtain corresponding critical bursting force. As a result, we proposed an empirical formula predicting the critical bursting force of one chamber infusion bag with specified geometry size. Besides, a theoretical analysis, which determines the force condition of three chamber infusion bag when falling from high altitude, was conducted. The proportion of force loaded on different chamber was gained. The results indicated that critical bursting force is positively related to the length and width of the chamber, and negatively related to the height of the chamber. While the infusion bag falling, the impact force loaded on each chamber is proportional to the total liquid within it. To raise the critical bursting force of in fusion bag, a greater length and width corresponding to reduced height are recommended considering the volume of liquid needed to be filled in.

Sc(OTf)3-catalyzed [3 + 2]-cycloaddition of nitrones with ynones.

An efficient approach to access functionalized (2,3-dihydroisoxazol-4-yl) ketones has been developed by reacting nitrones 4 with ynones 7 or terminal ynones 10 in a one-pot fashion. The reaction went through a formal Sc(OTf)3-catalyzed [3 + 2]-cycloaddition process to generate a number of functionalized (2,3-dihydroisoxazol-4-yl) ketones 11aa-11aw, 11ba-11la and 12aa-12ae in moderate to good yields.

Synthesis of the Sex Pheromone of the Tea Tussock Moth Based on a Resource Chemistry Strategy.

Synthesis of the sex pheromone of the tea tussock moth in 33% overall yield over 10 steps was achieved. Moreover, the chiral pool concept was applied in the asymmetric synthesis. The synthesis used a chemical available on a large-scale from recycling of wastewater from the steroid industry. The carbon skeleton was constructed using the C4+C5+C8 strategy. Based on this strategy, the original chiral center was totally retained.

Asymmetric Total Synthesis of Four Stereoisomers of the Sex Pheromone of the Western Corn Rootworm.

A convergent synthesis of four stereoisomers of the sex pheromone of the western corn rootworm (8-methyldecan-2-yl propionate, 1) from commercially available chiral starting materials is reported. The key step was Julia-Kocienski olefination between chiral BT-sulfone and chiral aldehyde. This synthetic route provided the four stereoisomers of 1 in 24-29% total yield via a six-step sequence. The simple scale-up strategy provides a new way to achieve the asymmetric synthesis of the sex pheromone.

Syntheses of Benzo[c]Chromen-6-ones by Palladium Catalyzed C-H Bond Activation using Diazonium Salts.

An efficient palladium catalyzed C-H bond activation for the synthesis of benzo[c]chromen-6-ones using diazonium salts is described. In the presence of Pd(OAc)2, dppp, PivOH and K2CO3, the diazonium salt can be transformed into the product through a denitrogenation/C-H bond activation/cyclization sequence in acetonitrile. Altogether, nine structurally diverse substituted benzoLc]chromen-6-ones were prepared in excellent yields through two different methods.

Preparing (Multi)Fluoroarenes as Building Blocks for Synthesis: Nickel-Catalyzed Borylation of Polyfluoroarenes via C-F Bond Cleavage.

The [Ni(IMes)2]-catalyzed transformation of fluoroarenes into arylboronic acid pinacol esters via C-F bond activation and transmetalation with bis(pinacolato)diboron (B2pin2) is reported. Various partially fluorinated arenes with different degrees of fluorination were converted into their corresponding boronate esters.

Divergent Method to trans-5-Hydroxy-6-alkynyl/alkenyl-2-piperidinones: Syntheses of (-)-Epiquinamide and (+)-Swainsonine.

An efficient diastereoselective approach to access trans-5-hydroxy-6-alkynyl/alkenyl-2-piperidinones has been developed through nucleophilic addition of α-chiral aldimines using alkynyl/alkenyl Grignard reagents. The diastereoselectivity of alkenyl in C-6 position of 2-piperidinone was controlled by α-alkoxy substitution, while the alkynyl was controlled by the coordination of the α-alkoxy substitution and stereochemistry of sulfinamide. The utility of this straightforward cascade process is demonstrated by the asymmetric synthesis of the (-)-epiquinamide and (+)-swainsonine.

Diastereoconvergent synthesis of trans-5-hydroxy-6-substituted-2-piperidinones by addition-cyclization-deprotection process.

A diastereoselective one-pot approach to access trans-5-hydroxy-6-substituted-2-piperidinones by an addition-cyclization-deprotection process has been developed, in which the stereogenic center at the C-6 position was solely controlled by α-OTBS group. The utility of this transformation is demonstrated by the asymmetric synthesis of the enantiomer of (-)-CP-99,994.

Alkene oxyalkylation enabled by merging rhenium catalysis with hypervalent iodine(III) reagents via decarboxylation.

Rhenium-catalyzed oxyalkylation of alkenes is described, where hypervalent iodine(III) reagents derived from widely occurring aliphatic carboxylic acids were used as, for the first time, not only an oxygenation source but also an alkylation source via decarboxylation. The reaction also features a wide substrate scope, totally regiospecific difunctionalization, mild reaction conditions, and ready availability of both substrates. Mechanistic studies revealed a decarboxylation/radical-addition/cation-trapping cascade operating in the reaction.

A facile synthesis of (+/-)-heliannuol-D.

A facile synthesis of (+/-)-heliannuol-D 1, which serves as an allelopathic chemical in nature and a potential lead compound in the search for new herbicides, has been achieved in a linear 11 steps, together with its epimer. The synthesis commenced with 4-methoxy-3-methyl-acetophenone, through the Baeyer-Villiger reaction, lithiation and addition, epoxidation and intramolecular cyclization to give (+/-)-heliannuol-D (1) and its epimer (la) in 32.6% overall yield. Our synthetic approach is cost-effective; this will be helpful in applying this kind of compound for the development of a new generation of agrochemicals.

A facile and efficient synthesis of diaryl amines or ethers under microwave irradiation at presence of KF/Al2O3 without solvent and their anti-fungal biological activities against six phytopathogens.

A series of diaryl amines, ethers and thioethers were synthesized under microwave irradiation efficiently at presence of KF/Al2O3 in 83%-96% yields without any solvent. The salient characters of this method lie in short reaction time, high yields, general applicability to substrates and simple workup procedure. At the same time, their antifungal biological activities against six phytopathogen were evaluated. Most of the compounds (3b, 3c, 3g-o) are more potent than thiophannate-methyl against to Magnaporthe oryzae. This implies that diaryl amine or ether moiety may be helpful in finding a fungicide against Magnaporthe oryzae.

A facile asymmetric synthesis of (s)-14-methyl-1-octadecene, the sex pheromone of the peach leafminer moth.

An asymmetric synthesis of 14-methyl-1-octadecene, the sex pheromone of the peach leafminer moth has been achieved. The target molecule was synthesized in six linear steps and in 30.3% overall yield from commercially available hexanoyl chloride, (S)-4-benzyloxazolidin-2-one and 1,9-nonanediol. The hexanoyl chloride was connected with (S)-4-benzyloxazolidin-2-one, and with the induction of the chiral oxazolidinone auxiliary, after chiral methylation, LAH reduction and then tosylation gave the chiral key intermediate 5 in high stereoselectivity. 1,9-Nonanediol, was selectively brominated, THP protected and subjected to Li2CuCl4-mediated C-C coupling to afford a C12 intermediate. The target molecule, (S)-14-methyl-1-octadecene, was obtained after the two parts were subjected to a second Li2CuCl4-mediated C-C coupling. Our synthetic approach represents the first time a substrate-control asymmetric synthesis of (S)-14-methyl-1-octadecene has been reported.

Combining transition metal catalysis and organocatalysis--an update.

The combination of transition metal catalysis and organocatalysis as a new and exciting research area has attracted increasing attention as it can enable the development of unprecedented transformations that is not possible by use of either of the catalytic systems alone, and can improve the reactivity, efficiency and stereocontrol of existing chemical transformations. In this review, we summarize recent remarkable progress in the field of combined transition metal catalysis and organocatalysis, further highlighting the potential of this new and exciting research area and the many challenges that still remain for the future.

Thiophene-functionalized octupolar triindoles: synthesis and photophysical properties.

Two thiophene-functionalized octupolar triindole molecules were synthesized through Suzuki and Sonogashira cross-coupling reactions. Their photophysical and electrochemical properties were explored. The spectroscopic data demonstrate that triindole is an excellent rich electronic central donor for building octupolar optoelectronic molecules and possesses excellent luminescent properties. Thiophenylethynyl substituted triindole compound 3,8,13-tri(2-thiophenylethynyl)-5,10,15-tributyltriindole forms an intermolecular aggregation induced by π-π stacking from the rigid coplanar molecular scaffold. The redox curves and results of theoretical calculation imply that the two compounds have low ionization potential and low E(1/2 oxd), which may be originated from the high electronic density of both triindole and thiophene groups.

An improved synthesis of 1,2-diarylethanols under conventional heating and ultrasound irradiation.

A simple and efficient synthesis of 1,2-diarylethanols has been developed. The procedure involved the reaction between a variety of toluene derivatives and aryl aldehydes under conventional heating and ultrasound irradiation. This procedure possesses several advantages such as operational simplicity, high yield, safety and environment benignancy. Ultrasound was proved to be very helpful to the reaction, markedly improving the yield and the reaction rate.

3,4-Bis(4-meth-oxy-phen-yl)-2,5-dihydro-1H-pyrrole-2,5-dione.

In the title compound, C(18)H(15)NO(4), the benzene rings form quite different dihedral angles [16.07 (1) and 59.50 (1)°] with the central pyrrole ring, indicating a twisted mol-ecule. Conjugation is indicated between the five- and six-membered rings by the lengths of the C-C bonds which link them [1.462 (3) and 1.477 (3) Å]. The most prominent feature of the crystal packing is the formation of inversion dimers via eight-membered {⋯HNCO}(2) synthons.

Improved synthesis of 5-substituted 1H-tetrazoles via the [3+2] cycloaddition of nitriles and sodium azide catalyzed by silica sulfuric acid.

A silica supported sulfuric acid catalyzed [3+2] cycloaddition of nitriles and sodium azide to form 5-substituted 1H-tetrazoles is described. The protocol can provide a series of 5-substituted 1H-tetrazoles using silica sulfuric acid from nitriles and sodium azide in DMF in 72%-95% yield.

Rhenium-catalyzed regiodivergent addition of indoles to terminal alkynes.

An efficient rhenium-catalyzed site-switchable addition of indoles to terminal alkynes is described. A variety of bisindolylalkane derivatives are expeditiously synthesized in high yields with excellent regioselectivity. Preliminary mechanistic study sheds light on the observed regiodivergent addition.

2-Meth-oxy-4-methyl-1-[1-(phenyl-sulfon-yl)propan-2-yl]benzene.

The title mol-ecule, C(17)H(20)O(3)S, displays a U-shaped structure; the two benzene rings are nearly parallel and partially overlapped to each other, the dihedral angle and centroid-to-centroid distance being 15.0 (2)° and 3.723 (2) Å. In the crystal, weak inter-molecular C-H⋯O hydrogen bonds link the mol-ecules, forming supra-molecular chains running along the a axis.