Latest ArticlesFrom a mixture of α-, β- and γ-himachalenes extracted from waste wood of Atlas cedar (Cedrus atlantica), cadalene (1, 6-dimethyl-4-isopropylnaphthalene) and iso-cadalene (1, 6-dimethyl-3-isopropylnaphthalene) were produced in two steps with up to 71%±5% yield through the ar-himachalene intermediate using I2 and/or AlCl3 as reagents. The selectivity is shown to sharply depend on the operating conditions: while I2/AlCl3 in dichloromethane promotes the formation of cadalene, the formation of iso-cadalene is favored in the presence of AlCl3 in cyclohexane. The bicyclic aromatic compounds were thus obtained through unique rearrangements involving sequential C—C bond cleavage/formation and hydride transfer processes. In the absence of AlCl3 or I2, dihydrocurcumene was also found to be formed with up to 70% selectivity. A tentative mechanism is proposed and discussed.
By virtue of electrochemistry, a series of α, α-dihaloacetophenones were easily obtained with good to excellent yields. This electrochemical procedure was taken in a divided cell with constant current in aqueous media. The reaction can be carried out smoothly at room temperature under metal and oxidant free condition, which provides an eco-friendly synthesis for the α, α-dihaloacetophenone derivatives.
Rh/ZhaoPhos-catalyzed asymmetric hydrogenation of a series of (E)-2-(chroman-4-ylidene)acetates was successfully developed to prepare various chiral 4-substituted chromanes with high yields and excellent enantioselectivities (up to 99% yield, 98% ee). Moreover, the gram-scale hydrogenation could be performed well in the presence of 0.02 mol% catalyst loading (TON = 5000), the hydrogenation product was easily converted to access other important compounds, which demonstrated the synthetic utility of this asymmetric catalytic methodology.
A metal-free photocatalytic oxidative decarboxylation reaction at room temperature was developed for the synthesis of aromatic aldehydes and ketones from the corresponding arylacetic acids. The reaction was realized under blue-light irradiation by adding 1 mol% of 4CzIPN as photocatalyst and air as oxidant. This reaction represents a novel decarboxylation of a sp3-hybridized carboxylic acids without traditional heating, additional oxidants, and metal reagents under mild conditions.
Aerobic oxidation using pure dioxygen gas as the oxidant has attracted much attention, but its application in synthetic chemistry has been significantly hampered by the complexity of catalytic system and potential risk of high-energy dioxygen gas. By employing 1, 2-diethoxyethane as a catalyst and ambient air as an oxidant, an efficient protocol for the construction of various aryl-alkyl and diaryl ketones through oxidative cleavage of gem-disubstituted aromatic alkenes under minimal solvent conditions has been achieved.
Insulin fibrillation poses a variety of problems in biomedical and biotechnological applications of insulin. Inhibiting insulin fibrillation is highly on demand to address those problems. We herein demonstrate the capability of amphiphilic sulfonatocalixarene to inhibit insulin fibrillation. The amphiphilic assembly of p-sulfonatocalix[4]arene tetra dodecyl ether exhibits much better efficiency on inhibiting insulin fibrillation, with respect to p-sulfonatocalix[4]arene and sodium dodecyl benzenesulphonate. The pronounced inhibition effect results from both the preorganized scaffold of calixarene and the amphiphilic assembly.
N, N'-Disulfonylhydrazines have been proven to be the most reactive precursors of the sulfonyl radicals among all types of sulfonyl substituted hydrazines as early as half a century ago. However, the sulfonyl radicals generated from these compounds have not been used in organic synthesis except the simple selfdimerization synthesis of disulfones controlled by the “solvent-cage-effects”. In this article, N, N'-disulfonylhydrazines were introduced as new sulfonylating reagents and their combinations with NIS were disclosed as new iodosulfonylating reagents of alkynes. Finally, a highly efficient method for the synthesis of (E)-β-iodovinyl arenesulfones was developed by mixing an alkyne, a N, N'-disulfonylhydrazine and NIS in aqueous THF at room temperature for 5 min.
To improve aqueous solubility and anti-ischemic activity of 3-n-butylphthalide (NBP), we designed and synthesized the ring-opened derivative of NBP-ferulic acid-glucose trihybrids (S1-S8). These hybrids inhibited adenosine diphosphate (ADP)- or arachidonic acid (AA)-induced platelet aggregation, among them, S2 was 30-fold more water-soluble, and over 10-fold more potent in inhibition of platelet aggregation, as well as reduced ROS generation and protected primary neuronal cells from OGD/Rinduced damage, in comparison with NBP. Additionally, S2 was more active than its three moieties alone or in combination, suggesting that the activity of S2 may be attributed to the synergistic effects of these moieties. Importantly, in vivo studies indicated that S2 not only possessed good pharmacokinetic profile, but also improved NBP distribution in rodent brain, suggesting that the glucose moiety in S2 may be recognized by glucose transporter 1 (GLUT1) on blood-brain barrier (BBB), promoting it to penetrate through BBB. Our findings suggest that S2 may be a promising candidate for the intervention of ischemic stroke, warranting further study.
Se/C as a novel carbon-based biomaterial was prepared by using cheap and abundant glucose as the carbon source. It was highly active and could well restrain Xanthomonas campestris pv. campestris (EC50 = 4.7403 μg/mL), a very harmful germ causing the devastating cabbage black rot disease and resulting in huge economic losses. As a type of carbon material insoluble in water, Se/C is bio-compatible and can adhere onto the leaves of the plants to allow a slow and sustained release of its efficacy, affording an efficient method for the cabbage black rot disease prevention and cure. This work as the first report on the bioactivity studies of Se/C significantly expands the application scopes of the selenium-containing materials and may draw continuous attentions from a broad field.
Manganese-catalyzed hydrogenation of unsaturated molecules has made tremendous progresses recently benefiting from non-innocent pincer or bidentate ligands for manganese. Herein, we describe the hydrogenation of quinolines and imines catalyzed by simple manganese carbonyls, Mn2(CO)10 or MnBr(CO)5, thus eliminating the prerequisite pincer-type or bidentate ligands.
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