Pd-Cu catalyzed heterocyclization during Sonogashira coupling: synthesis of 2-benzylimidazo[1,2-a]pyridine

The reaction of 2-amino-1-(2-propynyl)pyridinium bromide with various iodobenzenes, catalyzed by Pd-Cu, leads to the formation of 2-benzylimidazo[1,2-a]pyridines.     

Highly efficient CuOx/OMS-2 catalyst for synthesis of phenoxathiin derivatives via intramolecular arylations of phenols with aryl halides

Phenoxathiin and its derivatives have attracted a great deal of interest due to their unique chemical and physical properties and their applications in fluorescent materials, antifungal activities and selective inhibitors. In the presence of copper supported on manganese oxide-based octahedral molecular sieves OMS-2 (CuO_x/OMS-2), the heterogeneously catalytic synthesis of phenoxathiinan derivatives via intramolecular arylations of phenols with aryl bromide or aryl chloride has been achieved. TEM and XRD have confirmed the CuO_x/OMS-2 catalyst has been successfully reused 8 times without a significant decrease in the yield, with simple filtration and washing as a means of separation.     

Ag/Cu-mediated decarboxylative cyanation of aryl carboxylic acids with K4Fe(CN)6 under aerobic conditions

A method for facile synthesis of aryl nitriles has been well established via Ag/Cu-mediated decarboxylative cyanation of benzoic acids with K₄Fe(CN)₆ under aerobic conditions. The approach of using readily accessible aryl carboxylic acids and green K₄Fe(CN)₆ as starting material provides a feasible alternative to previous cyanation protocols. Control experiments revealed the key role of Cu for the process and excluded the possibility of a radical mechanism for the transformation.     

Copper-mediated O-arylation of lactols with aryl boronic acids

A novel and efficient method to access phenolic glycosides has been established by using copper-mediated coupling reaction of aryl boronic acids with hemiacetals. The reaction enjoyed a wide range of substrate scope, and many phenolic glycosides can be synthesized in good yields.     

Reversible double insertion of aryl isocyanates into the Ti-O bond of titanium(IV) isopropoxide

The insertion of phenyl isocyanate into titanium isopropoxide leads to the formation of a dimeric complex [Ti(OⁱPr)₂(μ-OⁱPr){C₆H₅N(OⁱPr)CO}]₂ (1) which has been structurally characterized. Reaction of titanium isopropoxide with two and more than 2 equiv. of phenyl isocyanate is complicated by competitive, reversible insertion between the titanium carbamate and titanium isopropoxide. The ligand formed by insertion of phenyl isocyanate into the titanium carbamate has been structurally characterized in its protonated form C₆H₅N{C(OⁱPr)O}C(O)N(H)C₆H₅ (3aH). Insertion into the carbamate is kinetically favored whereas insertion into isopropoxide gives the thermodynamically favored product.     

Iodine/MeOH: a novel and efficient reagent system for thiocyanation of aromatics and heteroaromatics

Indoles, pyrroles, oxindoles and aromatic amino compounds undergo smooth thiocyanation with ammonium thiocyanate in the presence of molecular iodine in methanol under mild conditions to afford the corresponding 3-indolyl, 2-pyrrolyl and 4-aryl thiocyanates, respectively, in excellent yields with high selectivity. The reactions proceed rapidly at room temperature without heating or the use of strong Lewis acids.     

Selective Oxidation of Aryl Ketones to α-Diketones with 4-Aminoperoxybenzoic Acid Supported on Silica Gel in Presence of Air

Summary. 4-Aminoperoxybenzoic acid supported on silica gel in presence of air was found to be a selective and convenient oxidant for the oxidation of methylene groups in aryl ketones to convert them to -diketones.     

The sequel to a carbocyclic nucleoside synthesis: a divergent access to both arenediazonium ions and aryl triflates

Depending on the amount of acid used, treating aryl-dialkyl triazenes of general structure 3 with triflic acid resulted in the formation of either the corresponding arenediazonium triflates 4 or aryl triflates 8 apparently by two different pathways, the latter conversion being favoured at high acid concentration.     

A new binding motif in molecular clips: 1-D polymeric self-inclusion in a phenol complex of a bis(methoxyphenyl)glycoluril

Nolte's bis(o-xylylenyl)diphenylglycoluril molecular clips, in which the phenyls act as conformational ‘locks’ of the receptor site, have been modified with p-methoxy substituents on the phenyls. While this change does not have a major effect on the complexation of guests such as resorcinol (m-dihydroxybenzene) in chloroform solution, it allows for new binding geometries in the solid state. The crystal structure of new host 1,6:3,4-bis(1,2-xylylene)tetrahydro-3a,6a-bis(4-methoxyphenyl)-imidazo[4,5-d]imidazole-2,5(1H,3H)-dione (11) complexed with 4-phenylphenol (4-PP) has been determined as its toluene solvate [(11):2(4-PP):0.5(C₇H₈)]. Molecules of 11 aggregate in 1-D chains through polymeric self-inclusion via C-H?π(aromatic) interactions: 2-D sheets form via aryl stacking of the 1-D chains and the 3-D structure consists of alternating sheets of 11 in between which sheets of (4-PP):0.5(C₇H₈) reside.