The first synthesis of 2-methyl-6-pentadecyl-Δ1,6-piperideine (1), a major alkaloid of the piperideine chemotype in fire ant venoms, and its analogues, 2-methyl-6-tetradecyl-Δ1,6-piperideine (2) and 2-methyl-6-hexadecyl-Δ1,6-piperideine (3), was achieved by a facile synthetic method starting with glutaric acid (4) and urea (5). Compound 1 showed in vitro antifungal activity against Cryptococcus neoformans and Candida albicans with IC50 values of 6.6 and 12.4 μg/mL, respectively, and antibacterial activity against vancomycin-resistant Enterococcus faecium with an IC50 value of 19.4 μg/mL, while compounds 2 and 3 were less active against these pathogens. All three compounds strongly inhibited the parasites Leishmania donovani promastigotes and Trypanosoma brucei with IC50 values in the range of 5.0–6.7 and 2.7–4.0 μg/mL, respectively.

Herein, via integrating the merits of Fe-based nanoparticles and graphene oxide, magnetic Al/Fe oxide nanoparticles implanted on reduced N-doped graphene oxide (Al/Fe oxide RNGO) were synthesized by solvothermal reaction followed by thermal annealing with a particular temperature and hold time. The synthesized catalyst exhibited excellent performance with more than 80% yield of the desired product benzaldehyde achieved within a 2-hour reaction time. Due to its distinctive magnetism, the material can easily be separated and recycled for subsequent runs. It also demonstrated exceptional stability and recyclability with regard to its performance in a lifetime test without significant capacity or activity loss. The most remarkable finding was the observation of a color shift during the lifetime test due to the change in the morphology, which was further connected with the catalytic performance; initially, a chaotic structure and a comparable inferior catalytic activity were obtained, whereas a waffle or pastry state and a relatively superior activity were observed later. An additional reference without reactants did not display this morphology change; this result supported the employment of the catalyst in the reaction and provided a new alternative methodology to deduce and verify the mechanism.

A series of novel asymmetric azo reagents, 1-(tert-butyl)-2-(4-substituted benzyl) azodicarboxylate, were prepared. The synthetic process has the advantage of simpleness, easy operation, mild reaction condition and high yield. The 1-(tert-butyl)-2-(4-chlorobenzyl) azodicarboxylate (tBCAD) was selected for its stability and convenience to handle, and its precursor can be recycled by recrystallization with toluene. The tBCAD and DIAD were applied to a wide variety of Mitsunobu reactions. The experimental results showed that the performance of tBCAD in Mitsunobu reaction was comparable to that of DIAD, while the stability of tBCAD was much better than DIAD. Thus, tBCAD can be a novel, stable, effective azo-reagent for the Mitsunobu reaction.Download high-res image (168KB)Download full-size image

A magnetically separable NiFe2O4 nanoparticle catalyst was prepared readily via a simple one-step hydrothermal process. The catalytic performance of this hetero-nanostructure was investigated by Kneovenagel condensation with aldehydes and active methylene compounds under mild conditions. The newly designed catalyst exhibited a prominent catalytic activity with 99.5% conversion, 99% selectivity and excellent yields, which is compatible with various aldehydes and active methylene compounds with good conversion and high selectivity as well. This easily separated hybrid (NiFe2O4), by exerting an external magnetic field, could be recycled for eight times without significant loss, which started a new era for low-cost fabrication of CC bond for extending usage in a large scale, especially in pharmaceutical and cosmetics industry.

This paper reports the asymmetric synthesis of an important pharmaceutical intermediate (3S)-1-[(1R)-2-hydroxy-1-phenylethyl]-3-methylpiperidin-2-one (compound 1) from commercially available D-plenylglycinol and delta-valerolactone. During the alkylation process, the hydroxyl group can be protected or unprotected, resulting in a different consumption of s-BuLi, and leading to a different diastereomeric excess (de) of compound 1. When 1-[(1R)-2-hydroxy-1-phenylethyl]-piperidin-2-one (compound 2) was alkylated with 2.5 eq. of s-BuLi, compound 1 was obtained as a single isomer detected by chiral high performance liquid chromatography (HPLC) columns with an overall yield of 91%. With the hydroxyl group protected, (R)-1-(2-[(tert-butyldimethylsil) oxy]-1-phenylethyl) piperidine-2-one (compound 6) could be alkylated with 1.5 eq. of s-BuLi, giving compound 1 and its diastereoisomer 8 in a ratio of 1:2.5 and a yield of methylation of 90%. Compounds 1 and 8 could be separated completely and easily by flash chromatography. The absolute configuration of compound 8 was determined by singlecrystal X-ray analysis. The mechanism of the alkylation process is discussed based on experimental results.探索合成(3S)-1-[(R)-2-羟基-1-苯乙基]-3-甲基-2-哌啶酮的新方法。以常规化工原料D-苯苷氨醇为主要原料, 在比 较温和的条件下合成重要的药物中间体(3S)-1-[(R)-2-羟基-1-苯乙基]-3-甲基-2-哌啶酮及其同系 物。该方法中的甲基化步骤较常规甲基化步骤 减少1 当量s-BuLi 的用量, 更环保和安全。利用D-苯苷氨醇的空间位阻作用, 在六元环内 酰胺中引入具有特定光学纯度的手性甲基。在 甲基化过程中, 用叔丁基二甲基氯硅烷对羟基 进行保护, 以减少仲丁基锂的用量。以工业易得的δ-戊内酯及D-苯苷氨醇为初始原 料, 探索合成3-甲基-2-哌啶酮类物质的新方 法。新方法中对仲丁基锂的消耗量与常规方法 有所不同。当羟基受保护时, 甲基化1 当量六 元环内酰胺(化合物7)消耗1.5 当量而非2.5 当量仲丁基锂, 甲基化产物脱掉醇羟基保护 基, 得到(3S)-1-[(R)-2-羟基-1-苯乙基]-3-甲基-2- 哌啶酮(化合物1)及其非对映异构体(3R)-1- [(R)-2-羟基-1-苯乙基]-3-甲基-2-哌啶酮(化合物 8), 二者摩尔比为1:2.5。通过重结晶或柱层析 的方法可对二者进行完全分离。

The in situ growth of SnO2 nanoparticles on graphene have been achieved via a hydrothermal method and the nanocomposites were used as an efficient catalyst for the epoxidation of alkenes with aqueous hydrogen peroxide in nitrile based systems for the first time. Furthermore, the SnO2/graphene nanocomposites could be readily recovered and reused for at least ten consecutive cycles without significant loss of activity and selectivity.

A highly selective chemosensor (1) bearing three salphen pockets fulfilled the recognition of Cu2+ via obvious color change and significant absorption enhancement upon the introduction of Cu2+. Additionally, the coordination of 1 and Cu2+ led to the formation of coordination polymer which further generated nanospheres, as evidenced by SEM, TEM, AFM, PXRD, and EDX investigations.

The direct assembly of LDH nanosheets and organic molecules, such as Mn(II)–salen complex, into a sandwich-structured nanocomposite has been achieved via a modified flocculation method. When used as a catalyst, the obtained material has superior thermal stability and catalytic properties over a material prepared using a traditional ion exchange method in the oxidation of 4-picoline.

A novel chemosensor for fluoride anion has been developed. This sensor, constructed by merging six phenolyl units into a hexaazatriphenylene (HAT) core, could recognize F− visually and spectroscopically with high selectivity over other anions, which was demonstrated by naked-eye experiment and UV–vis absorption spectroscopy study.

Solubility of 2-amino-6-chloropurine in Mitsunobu solvents could be significantly improved after its exocyclic amino group is protected via N-tert-butoxycarbonylation. The bis-Boc protected 2-amino-6-chloropurine also shows excellent activity and N9 selectivity in the coupling with various alcohols by a Mitsunobu reaction. Then, a new practical and efficient method is established for the synthesis of penciclovir (PCV) from bis-Boc-2-amino-6-chloropurine 9 and the side chain of 5-(2-hydroxyethyl)-2,2-dimethyl-1,3-dioxane 5—the latter being a more easily prepared cyclic precursor of the diacetate side chain used in the conventional process. The coupling of 9 with 5 proceeded regioselectively at a N9 position of purine derivative for a good yield under Mitsunobu conditions.

A simple, efficient procedure is proposed for Knoevenagel condensations of 1,3-dicarbonyl compounds with aldehydes catalyzed by heterogeneous polystyrene-supported aluminum chloride (Ps-AlCl3) under solvent-free conditions. The condensations are carried out smoothly with high yields (87–98%) at 60 °C for 2–4 h in the presence of the Ps-AlCl3 catalyst. The catalyst is characterized by Fourier transfer-infrared spectroscopy (FT-IR). The catalyst is applicable to a wide range of aldehydes, and has excellent recyclability and can be reused several times without loss of activity.

Dicyclopentyl azodicarboxylate is introduced as a new azo-reagent which can be conveniently prepared in two steps and be used in the Mitsunobu reaction. Though there are no distinct difference of reactivity between DCpAD and DEAD, the former is a more preferable azo-reagent for its stability.

An efficient enzymatic method for the synthesis of (S)-3-substituted glutaric acid monoesters which was aided by molecular docking has been described. The reaction was proceeded under mild conditions, and the desired products were afforded with up to 98% ee in the yield of 93%. The results demonstrate that molecular docking is efficient to facilitate selection of substrates in enzymatic reaction.An efficient enzymatic method for the synthesis of (S)-3-substituted glutaric acid monoesters which was aided by molecular docking has been described. The reaction was proceeded under mild conditions, and the desired products were afforded with up to 98% ee in the yield of 93%. The results demonstrate that molecular docking is efficient to facilitate selection of substrates in enzymatic reaction.

Heat capacities of binary mixtures of acetic acid with acetic anhydride and methenamine were measured by a cooling method with a simple calorimeter from (308.15 to 333.15) K at atmospheric pressure with different compositions. The excess molar heat capacities of the binary mixture of acetic acid with acetic anhydride were calculated from the experimental data and were fitted to the Redlich−Kister equation.

Densities and viscosities of the binary mixtures of cyclopropanecarboxylic acid with methanol, ethanol, propan-1-ol, and butan-1-ol have been measured at different temperatures (298.15, 308.15, 318.15, 328.15, and 338.15) K and atmospheric pressure over the whole range of compositions. The excess molar volumes were calculated from the experimental data and correlated by the Redlich−Kister polynomial equation. McAllister’s three-body and four-body interaction models are also used to correlate the kinematic viscosities of these binary mixtures.

Densities and viscosities of the binary mixtures of methyl 4-chlorobutyrate with benzene, toluene, o-xylene, m-xylene, and p-xylene have been measured at different temperatures (298.15, 308.15 and 318.15) K and atmospheric pressure over the whole range of compositions. The excess molar volumes were calculated from the experimental data and correlated by the Redlich−Kister polynomial equation. McAllister’s three-body and four-body interaction models are also used to correlate the kinematic viscosities of these binary mixtures.

The solubility of hexamethylenetetramine in pure water, methanol, acetic acid, and ethanol + water was measured by a synthetic method with temperature ranging from (299.38 to 340.35) K at atmospheric pressure. The laser monitoring observation technique was used to determine the disappearance of the solid phase in a solid + liquid mixture. The results were correlated by a semiempirical Apelblat equation.

Densities and viscosities of the binary mixtures of acetic acid + acetic anhydride have been measured at temperatures from (293.15 to 338.15) K and atmospheric pressure over the whole concentration range of compositions. The excess molar volume (VE) and viscosity deviation (Δη) were calculated from the experimental data and correlated by the Redlich−Kister equation. In addition, densities and viscosities of methenamine + acetic acid solutions were measured, and the results were represented by third-order and fourth-order (empirical) polynomials in terms of mole fraction of methenamine.