A mild, palladium(II)-catalyzed ring-forming aminoacetoxylation of alkenes is described. Treatment a range nitrogen nucleophiles with catalytic palladium(II) in the presence PhI(OAc)2 as oxidant resulted alkene aminoacetoxylation, affording variety nitrogen-containing heterocycles. Our studies indicate possibility for high levels reaction regio- and stereocontrol. It appears that this stereoselective trans difunctionalization thus useful alternative to related cis-selective, metal-catalyzed...

A photo opportunity: visible-light-excited iridium catalyst delivers electrons from an amine to organohalide. The electron transfer then induces reductive scission of the carbon–halogen bond, generating corresponding alkyl, alkenyl, and aryl radical that can undergo cyclization hydrodehalogenation reactions. Detailed facts importance specialist readers are published as "Supporting Information". Such documents peer-reviewed, but not copy-edited or typeset. They made available submitted by...

Visible light-induced photocatalytic aromatic C–H imidation with N -chlorophthalimide proceeds through a nitrogen-centered radical intermediate to furnish the corresponding -aryl products.

Abstract Herein we report a highly efficient method for nickel‐catalyzed C−N bond formation between sulfonamides and aryl electrophiles. This technology provides generic access to broad range of N‐aryl N‐heteroaryl sulfonamide motifs, which are widely represented in drug discovery. Initial mechanistic studies suggest an energy‐transfer mechanism wherein reductive elimination occurs from triplet excited Ni II complex. Late‐stage sulfonamidation the synthesis pharmacologically relevant...

A highly stereoselective palladium-catalyzed O-glycosylation reaction is described. The of a glycal 3-acetate or carbonate with the zinc(II) alkoxide acceptors establishes glycosidic linkage under palladium catalysis to give rise disaccharides as product in good yields and high stereoselectivity. In contrast Lewis acid mediated Ferrier procedure, anomeric stereochemistry this controlled by employed ligand. Whereas use complex acetate 2-di(tert-butyl)phosphinobiphenyl catalyst results...

The equivalent of an asymmetric addition to a carbonyl group with stabilized anion is accomplished by discriminating between the enantiotopic C−O single bonds gem-diacetate. In this way, enantioselective total syntheses two antifugal agents, sphingofungins E and F, have been accomplished. synthetic strategy based on series catalytic processes whereby all chiral centers are created high stereoselectivities. first stereocenters introduced allylic alkylation reaction gem-diacetate 9 azlactone...

Bei Licht betrachtet: Ein durch sichtbares angeregter Iridiumkatalysator überträgt Elektronen von einem Amin auf ein Organohalogenid. Der Elektronentransfer löst daraufhin die reduktive Spaltung der Kohlenstoff-Halogen-Bindung aus und erzeugt das entsprechende Alkyl-, Alkenyl- oder Arylradikal, Cyclisierungs- Hydrodehalogenierungsreaktionen eingehen kann. DIPEA=N,N-Diisopropylethylamin.

Abstract Herein we report a highly efficient method for nickel‐catalyzed C−N bond formation between sulfonamides and aryl electrophiles. This technology provides generic access to broad range of N‐aryl N‐heteroaryl sulfonamide motifs, which are widely represented in drug discovery. Initial mechanistic studies suggest an energy‐transfer mechanism wherein reductive elimination occurs from triplet excited Ni II complex. Late‐stage sulfonamidation the synthesis pharmacologically relevant...

Cyanine (Cy) dyes are among the most useful organic fluorophores that have found a wide range of applications in single-molecule and super-resolution imaging as well other biophysical studies. However, recent observations blueshifted derivatives Cy formed via photoconversion raised concerns to potential artifacts multicolor imaging. Here, we report mechanism for Cy5 Cy3 occurs upon photoexcitation during fluorescent Our studies show formal C2H2 excision from mainly through an intermolecular...

We have evaluated two synthetic epothilone analogues lacking the 12,13-epoxide functionality, 12,13-desoxyepothilone B (dEpoB), and F (dEpoF). The concentrations required for 50% growth inhibition (IC 50 ) a variety of anticancer agents were measured in CCRF-CEM/VBL1000 cells (2,048-fold resistance to vinblastine). By using dEpoB, dEpoF, aza-EpoB, paclitaxel, IC values 0.029, 0.092, 2.99, 5.17 μM, respectively. These represent 4-, 33.5-, 1,423- 3,133-fold resistance, respectively, when...

Kendomycin, also known as (-)-TAN 2162, is a novel polyketide-derived ansamycin isolated from Streptomyces sp., which exhibits potent antagonist and agonist activities at the endothelin calcitonin receptors, respectively. This bacterial metabolite possesses strong antibiotic activity against range of gram-positive -negative bacteria cytostatic effects on growth human cancer cell lines. When macroglycosidation reaction employed key step, first enantioselective total synthesis kendomycin has...

A highly chemo- and stereoselective palladium-catalyzed allylic etherification reaction is described. The use of zinc(II) alkoxides proved effective in promoting the addition oxygen nucleophile derived from aliphatic alcohols to η3-allylpalladium complexes. Using diethylzinc (0.5 equiv), 5 mol % Pd(OAc)2, 7.5 2-di(tert-butyl)phosphinobiphenyl THF, cross-coupling between various acetates proceeded at ambient temperature furnish ethers with high stereoselectivity.

A novel rhodium-catalyzed cycloisomerization has been developed which converts various acyclic enynes to their cyclic diene isomers with endoselectivity. Both [RhCl(COD)]2/P(4-FC6H4)3 and RhCl(PPh3)3 catalyst systems are effective in promoting the C-C bond-forming cyclization of furnish carbo- heterocycles good excellent yield. Deuterium labeling studies suggest that reaction proceeds through formation a rhodium vinylidene followed by subsequent [2 + 2] cycloaddition alkene ring-opening...

A mild and convenient nickel-catalyzed method for free-radical cyclization of organohalides is described. The use a NiCl(2)•DME/Pybox complex as the catalyst zinc powder in methanol efficiently promotes reductive various unsaturated alkyl halides to give carbo-, oxa-, azacycles products high yields.

A rhodium-catalyzed oxygenative [2 + 2] cycloaddition of terminal alkynes and imines has been developed, which gives β-lactams as products with high trans diastereoselectivity. In the presence a Rh(I) catalyst 4-picoline N-oxide, alkyne is converted to rhodium ketene species via oxidation vinylidene complex subsequently undergoes an imine give rise 2-azetidinone ring system. Mechanistic studies suggest that reaction proceeds through metalloketene rather than free intermediate. The new method...

A gem of a couple: The title reaction terminal alkynes with O and N nucleophiles proceeds in the presence [{Rh(cod)Cl}2], P(4-FC6H4)3, 4-picoline N-oxide. Alcohols, amines, water add to give esters, amides, carboxylic acids, respectively. involves formation rhodium vinylidene, oxidation ketene by oxygen transfer, nucleophilic addition. As service our authors readers, this journal provides supporting information supplied authors. Such materials are peer reviewed may be re-organized for online...

A novel rhodium-catalyzed cycloisomerization has been developed which converts N-propargyl enamine derivatives to their isomeric six-membered azacycles in good yields under mild reaction conditions. The [Rh(C2H2)2Cl]2/P(4-F−C6H4)3 catalyst, combination with DABCO as a base and DMF solvent, was found be effective promoting the cyclization process. is proposed proceed through an intramolecular nucleophilic attack of rhodium vinylidene followed by base-mediated proton-shunting play crucial role...

An efficient protocol for the modular synthesis of sulfones and sulfonyl derivatives has been developed utilizing sodium<italic>tert</italic>-butyldimethylsilyloxymethanesulfinate (TBSOMS-Na) as a sulfoxylate (SO₂²⁻) equivalent.

A ruthenium-catalyzed hydrative cyclization of enynes has been developed. The reaction converts a range 1,5-enynes bearing terminal alkyne and Michael acceptor moieties into cyclopentanone derivatives. From extensive catalyst screening experiments, trinuclear ruthenium complex, [Ru3(dppm)3Cl5]PF6, identified to be an effective in mediating the 1,1-difunctionalization alkynes. It is proposed that this novel umpolung proceeds through formation vinylidene, anti-Markovnikov hydration,...

Indoleamine 2,3-dioxygenases (IDOs) are tryptophan-catabolizing enzymes with immunomodulatory functions. However, the biological role of IDO2 and its relationship IDO1 unknown. To assess between IDO1, we investigated effects co-expression human (h) on hIDO1 activity. Cells co-expressing hIDO2 showed reduced tryptophan metabolic activity compared those expressing only. In a proteomic analysis, hIDO1-expressing cells exhibited enhanced expression proteins related to cell cycle amino acid...

A rhodium(I)-catalyzed tandem cyclization of alkynes has been developed. The reaction allows for multiple bond formations to occur at both the α- and β-positions under mild conditions yield a variety fused ring systems as products. In presence triethylamine complex derived from [Rh(COD)Cl]2 P(4-F-C6H4)3, terminal alkyne is converted rhodium alkynyl species which reacts with tethered alkyl halide β-position provide β,β-disubstituted alkenylidene complex. then undergoes additional closures...