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A selective, practical and general incorporation of fluoroalkyl groups into organic frameworks is of great interest for synthesis. Herein we report the first metal-free, initiator-free, and general photochemical perfluoroalkylation of a variety of N,N-dialkylhydrazones at room temperature in the absence of any external photocatalyst. It constitutes an important advance in perfluoroalkyl radical addition to CN π bonds for the synthesis of hydrazones instead of amines. Affordable and easily available perfluoroalkyl iodides serve as effective precursors. The excellent regio-, stereo- and chemoselectivity as well as the broad substrate scope make this a very promising synthetic tool.

The chiral tridentate spiro P-N-S ligands (SpiroSAP) were developed, and their iridium complexes were prepared. Introduction of a 1,3-dithiane moiety into the ligand resulted in a highly efficient chiral iridium catalyst for asymmetric hydrogenation of β-alkyl-β-ketoesters, producing chiral β-alkyl-β-hydroxyesters with excellent enantioselectivities (95-99.9% ee) and turnover numbers of up to 355,000.

Noble metal nanocrystals have been extensively utilized as promising catalysts for chemical transformations and energy conversion. One of their significant applications lies in electrode materials in fuel cells (FCs) due to their superior electrocatalytic performance towards the reactions both on anode and cathode. Nowadays, tremendous efforts have been devoted to improve the catalytic performance and minimize the usage of precious metals. Constructing multicomponent noble metal nanocrystals with complex structures provides the opportunity to reach this goal due to their highly tunable compositions and morphologies, leading to the modification of the related electrochemical properties. In this review, we first highlight the recent advances in the controllable synthesis of noble metal alloy complex nanostructures including nanoframes/nanocages, branched structures, concave/convex structures, core–shell structures and ultrathin structures. Then the effects of the well-defined nanocrystals on the modified and improved electrochemical properties are outlined. Finally, we make a conclusion with the points on the challenges and perspectives of the controllable synthesis of noble metal alloy complex nanostructures and their electrocatalytic performance.

Various substituted 1,4-disubstituted triazoles (III) are obtained by highly efficient Ru-catalyzed click reaction between terminal alkynes and organic azides.

A facile, one-pot synthesis of N -aryl propargylamine from aromatic boronic acid, aqueous ammonia, and propargyl bromide has been achieved under microwave-assisted conditions. The reactions can be smoothly completed within a total 10 min through a two-step procedure, including copper-catalyzed coupling of aromatic boronic acids with aqueous ammonia and following propargylation by propargyl bromide.

The title reaction provides highly concise and effective routes to related complex compounds including natural product derivatives.

By employing sanguinarine, a natural active quaternary isoquinoline alkaloid, as a model molecule, a series of structurally simple quaternary 2-aryl-3,4-dihydroisoquinolin-2-ium compounds were designed and synthesized and evaluated for in vitro acaricidal activity against P. cuniculi. A new approach towards the title compounds was developed with isochroman as starting material. The results showed that 22 of 24 tested compounds displayed the activity in varying degrees at 0.4 mg/mL. Fourteen compounds were significantly more effective than ivermectin, a standard acaricide, and 6-methoxy dihydrosanguinarine, a derivative of sanguinarine (p

Two new lignan glycosides (I) and (II) are isolated from Quercus glauca along with 14 known compounds.

A mild, inexpensive, and environmentally friendly synthesis of the title compounds (II) is developed.

The new deacetylation protocol is successfully applied to a variety of differently protected mono- and disaccharides.

(+)-Grindelic acid, synthesized enantioselectively from the levorotatory Wieland-Miescher ketone and (−)-linalool and necessarily formulated as 1a, is shown to be antipodal to the major diterpenoid of Grindelia species.

The odoriferous principle of black tea has been produced from 2,2-dimethylcyclopentanone. The reaction sequence begins with 1,2-addition of 5-lithio-2-methyl-2,3-dihydrofuran to this ketone and immediate acid-catalyzed ring expansion of the resulting carbinols to a separable pair of spiro ethers. Individual conversion of these diastereomers to α,β-unsaturated ketones is followed by tandem condensation with the methyllithium−lithium bromide complex and oxidation with pyridinium chlorochromate.

Bicyclo[3.2.1]octanediones such as 9, which are readily available by double carbonylation of (1,3-cyclohexadiene)iron tricarbonyl complexes according to Eilbracht, are amenable to regiospecific methylenation under Wittig conditions. Reduction of 10 with copper hydride leads to 11, which can be resolved by application of Johnson's sulfoximine technology and oxidized to give the enantiopure antipodes of 10. Variously substituted cyclopentenyl anions undergo 1,2-addition to 10, providing carbinols which are capable of anionic oxy-Cope rearrangement via chair transition states. These structural reorganizations are fully stereocontrolled and lead directly to functionalized dicyclopenta[a,d]cyclooctenes. When 11 is treated analogously, only [1,3] sigmatropy is observed and inversion of stereochemistry at the migrating carbon prevails. Both processes exhibit impressive scaffolding powers and are characterized by brevity.

An enantioselective synthesis of (+)-grindelic acid is described, confirming that the dextrorotatory enantiomer is antipodal to the natural diterpenoid. The optically pure bicyclic ketone 5 representing the AB ring system is constructed from the levorotatory Wieland−Miescher ketone and must therefore possess the absolute configuration shown. Coupling of 5 with the 5-lithio derivative of optically active 2,3-dihydrofuran 3 derived from (R)-(−)-linalool was effected for the purpose of realizing acid-catalyzed rearrangement with generation of the appropriate spirocyclic framework. This key step is highly stereocontrolled, leading predominantly to 7. Once the advanced intermediate 15 is available in this fashion, its subsequent exposure to oxidation and dehydration steps led to the target molecule. The synthesis demonstrates unequivocally that natural (−)-grindelic acid is a true labdane diterpenoid.

Our involvement with the de novo acquisition of taxusin (1) and taxol (2) has been fueled in large part by the enchanting structural features of these molecules and the much heralded antitumor efficacy of 2, particularly in patients beset with refractory ovarian, breast, and lung cancers.1 In combination with the unusual mode of action of 2, which exhibits a remarkable capacity for stabilizing microtubule assembly and deterring cell division,2 the intrinsically exciting promise shown by taxol for benefiting human health has commanded unrivaled attention.

A series of 2-styrylchromone analogs were synthesized and examined for their antiproliferative effects on a panel of carcinoma cells. Among the tested agents, only 4m exhibited a moderate activity with an IC 50 value of 28.9 μM against PC-3 cells which indicates the selectivity of PC-3 cells in response to 2-styrylchromones. In addition, 4q demonstrated the most antiproliferative effect with an IC 50 value of 4.9 μM against HeLa cells. Flow cytometric analysis and DAPI staining revealed that HeLa cells exposed to 4q as low as 5 μM induced cell death through sub-G1 arrest and DNA fragmentation. Furthermore, CoMFA analysis of tested 2-styrylchromones resulted in a q 2 of 0.459 to generate a 3D-QSAR model on BT483 cell line. Together, these results suggest a potential structural optimization and pharmacological study of 2-styrylchromones.

A highly efficient iodine-catalyzed allylation of 1,3-dicarbonyl compounds with a wide variety of allylic alcohols has been developed. The reaction is operationally straightforward and proceeds under very mild conditions at room temperature in good to excellent yields (up to 99%) and regioselectivity.

Guided by in vitro antineoplastic tests, two new cytotoxic C-21 steroidal glycosides, auriculosides A (1) and B (2), were isolated from the root of Cynanchum auriculatum, Their structures were determined on the basis of chemical evidence and extensive spectroscopic methods including one-dimensional and two-dimensional NMR. These compounds showed cytotoxic activities against PC3, Hce-8693, Hela, and PAA cell lines. (C) 2000 Elsevier Science Ltd. All rights reserved.