Efficient Friedel-Crafts alkylation of indoles and pyrrole with enones and nitroalkene in water

An operationally simple and entirely green protocol for heteropoly acid (10 mg) catalyst conjugate addition of indoles and pyrrole to unsaturated carbonyl compounds and nitroalkene in water at ambient temperature in good to excellent yields has been developed.     

Iridium-catalyzed formylation of amines with paraformaldehyde

Amines have been formylated using aqueous formaldehyde or paraformaldehyde and the iridium catalyst [Cp∗IrI₂]₂. Paraformaldehyde acts as both a formylating agent and an oxidant.     

Highly chemoselective addition of amines to epoxides in water

Aminolysis of a variety of epoxides by aliphatic and aromatic amines in water, in the absence of any catalyst with high yields, is reported. Beta-amino alcohols were formed under mild conditions with high selectivity and in excellent yields. [reaction: see text]     

Aminoalkylation with Aldehydes Mediated by Solid Lithium Perchlorate

The solid LiClO₄-mediated one-pot reaction of aldehydes with secondary amines and C nucleophiles afforded the corresponding aminoalkylation products in high yields. Unlike the previous reported procedure, the aminoalkylation of aldehyde was achieved in the presence of only 0.5 equivalents of solid lithium perchlorate in dichloromethane as the solvent with good to high yields at room temperature.     

μ‐3,4′‐Bi‐1,2,4‐triazole‐di‐μ‐chloro‐cuivre(II) monohydraté

In the title compound, μ‐3,4′‐bi‐1,2,4‐triazole‐di‐μ‐chloro‐copper(II) monohydrate, {[CuCl₂(C₄H₄N₆)]·H₂O}_n, the Cu atom is located in a distorted octahedron consisting of two N atoms and four Cl atoms. The structural unit is an infinite chain in which octahedral groups, connected by shared edges, are also linked by bitriazole mol­ecules. The bitriazole ligand, the Cu atom and the water O atom all lie on independent twofold axes. The structure is held together by hydrogen bonds between the water mol­ecules and the non‐coordinated N atoms of the ligand, and by van der Waals forces.     

Bis(ketenyl)benzenes: preparation,observation, and reaction with tetramethylpiperidin-1-yloxyl

1,2- and 1,3-Bis(ketenyl)benzenes formed by double dehydrochlorination and by double Wolff rearrangement, respectively, gave ketenyl IR absorption at 2115, and 2122, and 2116 cm^–1, respectively. Reaction of these bisketenes with the aminoxyl radical tetramethylpiperidin-1-yloxyl (TEMPO) gave the corresponding tetraadducts as mixtures of meso- and d,l-isomers. The kinetics of the reaction of 1,3-bis(ketenyl)benzene with TEMPO gave a rate constant comparable to that of the monoketene PhCH=C=O. The reactions proceed by the initial attack of TEMPO on the carbonyl carbon of one ketenyl group followed by fast capture of the intermediate radical by a second TEMPO, and then reaction of the remaining ketene.     

Waste-free thiolysis of epoxide in water with high yield

An environmentally benign and efficient process for the preparation of β-hydroxysulfides was developed by a practical and simple reaction of thiols with epoxides in water catalyzed by K₂CO₃ in high yields and short reaction times.     

On the proximinality of the unit ball of proximinal subspaces in Banach spaces: A counterexample

A known, and easy to establish, fact in Best Approximation Theory is that, if the unit ball of a subspace of a Banach space is proximinal in , then itself is proximinal in . We are concerned in this article with the reverse implication, as the knowledge of whether the unit ball is proximinal or not is useful in obtaining information about other problems. We show, by constructing a counterexample, that the answer is negative in general.