Zr-Catalyzed Microwave Assisted Functionalization of Alkyne and Nitroalkene

Water and zirconium(IV) as catalyst were found to be effective in the transformation of terminal aromatic alkyne to aromatic methyl ketone in the microwave. This terminal alkyne hydration reaction proceeded in excellent yield with Zr(cp)2Cl2. The reaction was moved efficiently in presence of electron donating or electron withdrawing substituent on aromatic ring. An eco-friendly synthesis of aldehyde by oxidative cleavage of nitroalkene was developed with Zr(cp)2Cl2 catalyst and water in microwave.

Naphthalen-2-yl 1-(Benzamido(diethoxyphosphoryl)methyl)-1H-1,2,3-triazole-4-carboxylate

We have previously published new biheterocyclic phospohonic -amino esters of the 1,2,3-triazole-benzimidazole and 1,2,3-triazole-carbazole type. The aim of the present paper was to describe a new phosponic aminoester bearing a triazole ring substituted in position 5 by an ester group. Thus, according to the same catalytic process used previously, the compound naphthalen-2-yl 1-(benzamido(diethoxyphosphoryl)methyl)-1H-1,2,3-triazole-4-carboxylate was synthesized with an excellent yield and high regioselectivity via the copper (I)-catalyzed alkyne–azide cycloaddition reaction (CuAAC), using diethyl (-azido(benzamido)methyl)phosphonate (1) as a dipole and 2- naphthyl propiolate as a dipolarophile (2). The structure of the new compound was fully characterized by 1D (31P, 1H, 13C) and 2D (1H-1H and 1H-13C) NMR spectroscopy, IR, and HRMS.

Intramolecular Chalcogenylation of Isooxazolines Mediated by PhICl2 and Diorganyl Disulfides or Diselenides

Reactive organosulfenyl chlorides (ArSCl) or selenenyl chlorides (ArSeCl), generated in situ from the reaction of PhICl2 with diorganyl disulfides or diselenides, enable the intramolecular oxidative cyclization/chalcogenylation of β,γ-unsaturated oximes, leading to the formation of a series of chalcogenylated isooxazolines in good to excellent yield.

An Efficient Carbonized Sugar Catalyzed Entry to 7,8-dihydro-2H-Chromen-5(6H)-ones

The present paper describes a facile entry to various substituted 7,8-dihydro-2H-chromen-5-ones under neat conditions using simple carbonized sugar as a catalyst. The reaction was promoted by visible light under neat or in acetic acid as a solvent with a catalyst to afford the desired products in good to excellent yield. Mild conditions coupled with ease of operation make the protocol synthetically attractive and may find widespread application for the synthesis of chromenone scaffold.

Group-Assisted-Purification Chemistry Strategy for the Efficient Assembly of Cyclic Fused Pyridinones

A group-assisted-purification (GAP) chemistry strategy based Ugi four-center three-component reaction (Ugi-4C-3CR) was explored. The reaction proceeded well to deliver the cyclic fused pyridinones selectively. Moreover, the reaction condition was mild and avoided additional chromatography or recrystallization work-up. Also, wide variations in substrates, such as anilines and aliphatic amines as well as amino alcohols and amino acid esters were all tolerated and achieved in good to excellent yields. Importantly, ladder-type cyclic fused pyridinones can be further constructed with excellent yield of 91%.

Crystal structures of three N-(pyridine-2-carbonyl)pyridine-2-carboxamides as potential ligands for supramolecular chemistry

The synthesis and single-crystal X-ray structures of three N-(pyridine-2-carbonyl)pyridine-2-carboxamide imides, with or without F atoms on the 3-position of the pyridine rings are reported, namely, N-(pyridine-2-carbonyl)pyridine-2-carboxamide, C12H9N3O2 (1), N-(3-fluoropyridine-2-carbonyl)pyridine-2-carboxamide, C12H8FN3O2 (2), and 3-fluoro-N-(3-fluoropyridine-2-carbonyl)pyridine-2-carboxamide, C12H7F2N3O2 (3). The above-mentioned compounds were synthesized by a mild, general procedure with an excellent yield, providing straightforward access to symmetrical and/or asymmetrical heterocyclic ureas. The crystal structures of 1 and 2 are isomorphous, showing similar packing arrangements, i.e. double layers of parallel (face-to-face) molecules alternating with analogous, but perpendicularly oriented, double layers. In contrast, the crystal structure of 3, containing a fluoro- group at the 3-position of both pyridine rings, shows molecular arrangements in a longitudinal, tubular manner along the c axis, with the aromatic pyridine and carbonyl/fluorine moieties facing towards each other.

Asymmetric synthesis of 3-phenyl-2,3-dihydro-1H-pyrrolo[3,2-b]pyridine-3-carbonitriles catalysed by phase transfer catalyst derived from tert-leucine.

Chiral phase transfer catalysts derived from tert-leucine were synthesized and used in the aymmetric synthesis of 4-azaindoline derivatives. By this method, both enantiomers of corresponding products were obtained in excellent yield (up to 99%) with high enantioselectivity (up to 91% ee) and diastereoselectivity (up to >99: 1 dr).

Synthesis of Pentasaccharide Repeating Unit Corresponding to the Cell Wall O-Polysaccharide of Salmonella enterica O55 Strain Containing a Rare Sugar 3-Acetamido-3-deoxy-d-fucose

A pentasaccharide repeating unit corresponding to the cell wall O-antigen of Salmonella enterica O55 containing a rare sugar, 3-acetamido-3-deoxy-d-fucose has been synthesized as its p-methoxyphenyl glycoside using a sequential stereoselective glycosylation strategy. A suitably functionalized 3-azido-3-deoxy-d-fucose thioglycoside derivative was prepared in very good yield and used in the stereoselective glycosylation reaction. Functionalized monosaccharide intermediates were prepared judiciously and stereoselectively assembled to get the desired pentasaccharide derivative in excellent yield.

Preparation of the Key Dolutegravir Intermediate via MgBr2-Promoted Cyclization

A novel approach for synthesizing the key dolutegravir intermediate is described via MgBr2-promoted intramolecular cyclization. Condensation of commercially available methyl oxalyl chloride and ethyl 3-(N,N-dimethylamino)acrylate afforded the vinylogous amide in an excellent yield. Subsequent substitution by aminoacetaldehyde dimethyl acetal and methyl bromoacetate gave rise to the expected precursor for cyclization, which was promoted by MgBr2 to highly selectively convert into pyridinone diester. The key dolutegravir intermediate was finally prepared by the selective hydrolysis of the corresponding diester via LiOH.

Ir-Catalyzed Site Selective Borylation of 8-Arylquinolines

We report a convenient method for the highly site selective borylation of 8-arylquinoline. The reaction proceeds smoothly in presence of catalytic amount of [Ir(OMe)(cod)]2 and 2-phenylpyridine derived ligand using bis(pinacolato)diborane as the borylating agent. The reactions occur with high selectivity with many functional groups, providing a series of borylated 8-aryl quinolines with good to excellent yield and excellent selectivity. The borylated compounds formed in this method can be transformed to various important synthons using known transformations.