Search

In this study, Ce 0.8 Er 0.2 O 2-α was prepared via a microemulsion method. Then, Ce 0.8 Er 0.2 O 2-α powder was mixed with melted NaCl-KCl (1:1 mol ratio) at the weight ratio of 80%: 20% to obtain Ce 0.8 Er 0.2 O 2-α -KCl-NaCl at 750 °C. Ce 0.8 Er 0.2 O 2-α and Ce 0.8 Er 0.2 O 2-α -KCl-NaCl were characterized by thermogravimetry analysis and differential scanning calorimetry (TGA-DSC), Raman spectrometer, X-ray diffraction (XRD) and scanning electron microscope (SEM). The log (σT) ~ 1000 T-1 plots and fuel cell performances of Ce 0.8 Er 0.2 O 2-α and Ce 0.8 Er 0.2 O 2-α -KCl-NaCl were tested at 400–700 °C. The maximum output power density of Ce 0.8 Er 0.2 O 2-α -KCl-NaCl was 187 mW cm-2 at 700 °C which is six times greater than that of Ce 0.8 Er 0.2 O 2-α. [ABSTRACT FROM AUTHOR]

We report a concise synthesis of tanikolide 1, which was obtained from ethyl 2-oxocyclopentanecarboxylate in four steps: alkylation, Baeyer–Villiger reaction, saponification, and reduction/lactonization, in 70% overall yield. Our strategy should be suitable for the preparation of 1 in multigram or larger quantities. The net result of the last two steps (i.e. saponification and reduction/lactonization) is an efficient reduction of the ethoxycarbonyl of 3 while keeping the lactone carbonyl intact. [Copyright &y& Elsevier]

Abstract: A convenient, economical, and practical protocol for borax-catalyzed thiolysis of 1,2-epoxides in aqueous medium has been developed, which has greatly expanded the utility scope of borax in organic synthesis. [Copyright &y& Elsevier]

A new efficient regioselective boron-assisted mono bromination methodology for arylamines is described. Our one-pot, three-stage approach (lithiation, boron amide formation and bromination) proved to be highly useful in mildly brominating a variety of arylamines in up to 94% yields. [Copyright &y& Elsevier]

Abstract: Racemic nonactic acid was efficiently constructed in a convergent, stereocontrolled fashion (7 steps, 27%). The present synthesis features a stereocontrolled 1,3-dione reduction with NaBH4/Et2B(OMe) and an acid-promoted stereospecific cyclization in the formation of 7. [Copyright &y& Elsevier]

We have developed an environmentally benign and practical protocol for the synthesis of pyrrolo[1,2- a ]quinoxalines, which represent ubiquitous structural units common to a number of biologically active compounds. This synthetic system features simple operation and using clean oxidant, as well as mild reaction conditions. Both aromatic and aliphatic aldehydes can be used for the reaction and the products were obtained in good to excellent yields. [ABSTRACT FROM AUTHOR]

The first enantioselective total synthesis of (−)-salprzelactone, a seco-norabietane diterpenoid has been accomplished in only three steps. Key transformations of the synthesis include an intermolecular aldol reaction and lactonization. [ABSTRACT FROM AUTHOR]

Abstract: We describe the efficient formal syntheses of both natural (−)-aphanorphine and unnatural (+)-aphanorphine from the same commercially available amino acid, (2S,4R)-4-hydroxyproline. The tricyclic framework was constructed by intramolecular Friedel–Crafts reaction. (1R,4S)-1-Methyl-8-methoxy-3-(4-toluenesulfonyl)-2,3,4,5-tetrahydro-1,4-methano-3-benzazepine (8) was synthesized in six steps from sulfonamide 3; (−)-aphanorphine methyl ether 24 was obtained in seven steps from lactone 10. Intramolecular etherification of 18 proceeded with excellent stereoselectivity in the presence of BF3·OEt2, which has paved an efficient synthetic route to a series of medicinally attractive heterocycles. [Copyright &y& Elsevier]

Abstract: The monoterpenoid pheromone (+)-eldanolide, a long range sex attractant, has been synthesized in four steps from the chiral 2,3-epoxy alcohol 4 in 36% overall yield. Our synthetic strategy features the formation of a 1,3-diol by regio- and stereoselective ring opening of 2,3-epoxy alcohol 4, an intermediate easily available from Sharpless asymmetric epoxidation. Other key steps include one carbon elongation, saponification, and lactonization. The present work constitutes a general method for the rapid synthesis of a number of related γ-lactone natural products. [Copyright &y& Elsevier]

Abstract: We describe the synthesis of a series of conformationally constrained nicotine analogues 2–5 from appropriate pyridine-containing enals, featuring an intramolecular azomethine ylide–alkene [3+2] cycloaddition. The objective of the current project is to develop new selective nAChRs-targeting ligands. Of the nicotine analogues that we have studied, the conformation-restricting ring B unit can be either a five-membered carbocycle, or a six-membered carbocycle or heterocycle. The present work constitutes a general method for rapid assembly of other related tricyclic nicotine analogues. [Copyright &y& Elsevier]

Abstract: We have presented two facile four-step syntheses of (±)-tanikolide from ethyl 2-oxocyclopentanecarboxylate. The overall chemical yields of the two sequences reached as high as 76 and 85%, respectively. The first strategy involved alkylation, Baeyer–Villiger reaction, saponification, and reduction/lactonization. The second approach for synthesizing tanikolide took advantage of the same intermediate, the alkylated ketoester 2 , which was converted to the target molecule in such three steps as deethoxycarbonylation, hydroxymethylation, and Baeyer–Villiger reaction. Our strategies are advantageous because of their high yields and suitability for the preparation of 1 in multigram or larger quantities. [Copyright &y& Elsevier]

Both a three-step and a five-step syntheses of monoterpene alkaloid (±)-oxerine from alcohol 6 have been accomplished. In the second approach, the synthetic efficiency was enhanced by implementing a one-pot protocol (deprotonation/silylation/ alkylation/desilylation). The construction of the cyclopenta[c]pyridine framework was realized by an intramolecular Heck reaction, which should be adaptable for the synthesis of other related monoterpene pyridine alkaloids. [Copyright &y& Elsevier]

The synthesis of pyrazolotetrazepin-7-ones from 1,3,5-triazinanes with N,N′-cyclic azomethine imines was achieved via a formal (5 + 2) pathway under thermal conditions. The annulation reaction is catalyst-free and additive-free. [Display omitted] • The synthesis of pyrazolotetrazepin-7-ones from 1,3,5-triazinanes with N,N′-cyclic azomethine imines was achieved via a formal (5 + 2) pathway under thermal conditions, which is catalyst-free and additive-free. • Different from traditional reaction modes of 1,3,5-triazinane in the literature, five atoms of 1,3,5-triazinane were involved in this annulation reaction, which is more fascinating and useful. • N,N'-cyclic azomethine imines were used as a two-atom synthon via releasing benzaldehyde, which is the first case in the literature. [ABSTRACT FROM AUTHOR]

This paper describes a two-step synthesis of 1-methyl-1,2,3,3a,4,8b-hexahydropyrrolo[3,2-f]pyrindine, a conformationally constrained nicotine analogue. The target molecule was effectively assembled by an intramolecular azomethine ylide-alkene [3+2] cycloaddition. The cyclization precursor, 4-allyl-3-pyridinecarboxaldehyde, was formed efficaciously in a single step from 3-pyridinecarboxaldehyde via sequential in situ protection, ortho lithiation, cuprate formation, allylation, and deprotection. The cuprate formation plays a vital role in minimizing/eliminating the extent of multiple alkylation. [Copyright &y& Elsevier]

(−)-Frontalin is an aggregation pheromone that has found application in selective exterminating of certain harmful insects. This paper discloses an expedite synthesis of (±)-frontalin from a symmetric molecule, 2,6-dimethyl-1,6-heptadiene, in 64% yield. The one-flask operation consists of double dihydroxylation, mono-cleavage, and acid-catalyzed intramolecular acetalation. Our unique strategy was also successfully applied to additional diene substrates such as 4a and 4b. [Copyright &y& Elsevier]

A 1,3-dipolar cycloaddition reaction of arynes with 3-diazoindolin-2-ones under mild conditions in excellent yields has been developed, which allows facile access to a library of labile spiro[indazole-3,3′-indolin]-2′-ones. Spiro[indazole-3,3′-indolin]-2′-imines could be obtained as well following the same protocol. The isomerization reaction of spiro[indazole-3,3′-indolin]-2′-ones under thermal or acidic conditions has been efficiently achieved to afford a wide range of indazolo-[2,3- c quinazolin-6(5H)-ones and the one-pot synthesis of indazolo-[2,3- c quinazolin-6(5H)-ones from arynes and 3-diazoindolin-2-ones is also described. Whereas, spiro[indazole-3,3′-indolin]-2′-imines could not undergo the same rearrangement. Image 1 • aSpiro[indazole-3,3'-indolin]-2'-ones and spiro[indazole-3,3'-indolin]-2'-imines could be obtained via 1,3-dipolar cycloaddition reactions of arynes. • c The isomerization reactions of spiro[indazole-3,3'-indolin]-2'-ones under thermal or acidic conditions have been achieved to afford indazolo-[2,3- c quinazolin-6(5H)-ones. • c One-pot synthesis of indazolo-[2,3- c quinazolin-6(5H)-ones from arynes and 3-diazoindolin-2-ones is extensively studied. [ABSTRACT FROM AUTHOR]