Palladium-Catalyzed Selective Benzylic C-H Alkylation of Aromatic Sulfonamides with Maleimides

An efficient method for the selective benzylic C-H alkylation of sulfonamides using maleimides has been developed. The reaction proceeds via the benzylic C(sp3)-H bond activation of sulfonamide in the presence of a Pd(II) catalyst without requiring any oxidant, additive, or external ligand. This methodology is highly compatible with a wide variety of substituted maleimides. A plausible reaction mechanism is also proposed to account for this alkylation reaction.

Bis(N-picolinamido)cobalt(II) Complexes Display Antifungal Activity toward Candida albicans and Aspergillus fumigatus

This report highlights the synthesis and characterization of ten new bis(N-picolinamido)cobalt(II) complexes of the type [(L)2 CoX2 ]0/2+ , whereby L=N-picolinamide ligand and X=diisothiocyanato (-NCS), dichlorido (-Cl) or diaqua (-OH2 ) ligands. Single crystal X-ray (SC-XRD) analysis for nine of the structures are reported and confirm the picolinamide ligand is bound to the Co(II) center through a neutral N,O binding mode. With the addition of powder X-ray diffraction (PXRD), we have confirmed the cis and trans ligand arrangements of each complex. All complexes were screened against several fungal species and show increased antifungal activity. Notably, these complexes had significant activity against strains of Candida albicans and Aspergillus fumigatus, with several compounds exhibiting growth inhibition of >80 %, and onecompound inhibiting Aspergillus fumigatus hyphal growth by >90 %. Conversely, no antifungal activity was exhibited toward Cryptococcus neoformans and no cytotoxicity towards mammalian cell lines.

Quinoline-Fused Lactones via Tandem Oxidation Cyclization: Metal-Free sp3 C-H Functionalization

A unique lactonization of 2-methyl-3-acyl-4-phenylquinolines using PhIO as the oxidant and selectfluor as an additive is reported. The reaction occurs under ambient conditions through tandem oxidation and cyclization of sp³ C-H bonds under metal-free conditions. The heterocycle-fused lactones are obtained in moderate to good yield.

Transient Directing Group Enabled Pd-catalyzed γ-C(sp3)-H Oxygenation of Alkyl Amines

We report a general protocol for γ-C(sp³)-H acyloxylation and alkoxylation of free amines using 2-hydroxynicotinaldehyde as the transient directing group. In the presence of an electrophilic fluorinating bystanding oxidant and acetic acid, a wide range of aliphatic amines could be oxygenated selectively at the γ-methyl positions. A vast variety of aryl, heteroaryl, and aliphatic acids could also be successfully coupled under this C-O bond formation reaction to afford amine containing esters. Switching the nucleophile from acids to alcohols enables alkoxylation of free amines. Importantly, natural products and drug molecules such as ibuprofen, isozepac, fenbufen, and lithocholic acid are all compatible coupling partners. Notably, synthesis of these mono-protected amino alcohols from free amino alcohols using conventional selective protection are not always feasible.

Bidentate Directing Groups: An Efficient Tool in C-H Bond Functionalization Chemistry for the Expedient Construction of C-C Bonds

During the past decades, synthetic organic chemistry discovered that directing group assisted C-H activation is a key tool for the expedient and siteselective construction of C-C bonds. Among the various directing group strategies, bidentate directing groups are now recognized as one of the most efficient devices for the selective functionalization of certain positions due to fact that its metal center permits fine, tunable, and reversible coordination. The family of bidentate directing groups permit various types of assistance to be achieved, such as N,N-dentate, N,O-dentate, and N,S-dentate auxiliaries, which are categorized based on the coordination site. In this review, we broadly discuss various C-H bond functionalization reactions for the formation of C-C bonds with the aid of bidentate directing groups.

Platinum(ii)-catalyzed selective para C-H alkoxylation of arylamines through a coordinating activation strategy

A highly efficient method to selectively install alkoxy onto the para position of arylamines via a coordinating activation strategy has been reported. Various substrates are compatible, providing the corresponding products in good to excellent yields. This strategy gives an efficient and practical solution for the synthesis of unsymmetrical aryl ethers. A free radical pathway mechanism is advised for transformation.

A versatile rhodium(iii) catalyst for direct acyloxylation of aryl and alkenyl C–H bonds with carboxylic acids

Rh(iii)-Catalyzed highly regioselective direct acyloxylation of aryl and alkenyl sp² C–H bonds with various carboxylic acids has been developed.

Iodobenzene-catalyzed synthesis of aryl sulfonate esters from aminoquinolines via remote radical C–O cross-coupling

A simple and efficient approach is established for the iodobenzene-catalyzed synthesis of aryl sulfonate esters from aminoquinolines via remote radical C–O cross-coupling in the absence of any transition metal catalysts.

Copper-catalyzed transformation of ketones to amides via C(CO)–C(alkyl) bond cleavage directed by picolinamide

Copper catalyzed chemoselective cleavage of the C(CO)–C(alkyl) bond leading to C–N bond formation with chelation assistance of N-containing directing groups is described.

Direct α-acyloxylation of organic sulfides with the hypervalent (diacyloxyiodo)benzene/tetra-n-butylammonium bromide (TBAB) reagent combination

A novel metal-free approach to directly synthesize α-acyloxy sulfides from readily available alkyl sulfides utilizing hypervalent (diacyloxyiodo)benzene and TBAB reagent combination was developed.

Synthesis of esters via sp3 C–H functionalisation

This review describes various methods for the synthesis of eleven classes of esters involving sp³ C–H functionalisation.

Cross-dehydrogenative coupling for the intermolecular C-O bond formation

The present review summarizes primary publications on the cross-dehydrogenative C-O coupling, with special emphasis on the studies published after 2000. The starting compound, which donates a carbon atom for the formation of a new C-O bond, is called the CH-reagent or the C-reagent, and the compound, an oxygen atom of which is involved in the new bond, is called the OH-reagent or the O-reagent. Alcohols and carboxylic acids are most commonly used as O-reagents; hydroxylamine derivatives, hydroperoxides, and sulfonic acids are employed less often. The cross-dehydrogenative C-O coupling reactions are carried out using different C-reagents, such as compounds containing directing functional groups (amide, heteroaromatic, oxime, and so on) and compounds with activated C-H bonds (aldehydes, alcohols, ketones, ethers, amines, amides, compounds containing the benzyl, allyl, or propargyl moiety). An analysis of the published data showed that the principles at the basis of a particular cross-dehydrogenative C-O coupling reaction are dictated mainly by the nature of the C-reagent. Hence, in the present review the data are classified according to the structures of C-reagents, and, in the second place, according to the type of oxidative systems. Besides the typical cross-dehydrogenative coupling reactions of CH- and OH-reagents, closely related C-H activation processes involving intermolecular C-O bond formation are discussed: acyloxylation reactions with ArI(O2CR)2 reagents and generation of O-reagents in situ from C-reagents (methylarenes, aldehydes, etc.).

Pd-catalyzed benzylic C–H oxidation of cyclotriveratrylene – product diversity

The inner-rim oxidation of CTV has been explored with palladium and an interesting array of CTV derivatives has been obtained by simple changes in the solvent/conditions employed.

Pd-catalyzed α-selective C(sp3)–H acetoxylation of amides through an unusual cyclopalladation mechanism

A novel Pd-catalyzed site-selective α-C(sp³)–H oxidation/acetoxylation of amides through an unusual [4,6]-bicyclic metallacycle intermediate was reported with 1-aminoanthraquinone as a new BDG.