We report the development of a silicon nanowire array-stabilized palladium nanoparticle catalyst, SiNA-Pd. Its use in the palladium-catalyzed Mizoroki-Heck reaction, the hydrogenation of an alkene, the hydrogenolysis of nitrobenzene, the hydrosilylation of an α,β-unsaturated ketone, and the C-H bond functionalization reactions of thiophenes and indoles achieved a quantitative production with high reusability. The catalytic activity reached several hundred-mol ppb of palladium, reaching a TON of 2 000 000.

An in-water dehydrative alkylation with a novel heterobimetallic polymeric catalyst is described. Thus, a boron-iridium heterobimetallic polymeric catalyst was prepared by ionic convolution of a poly(catechol borate) and an iridium complex. The alkylation of ammonia and amines with alcohols, alkylating agents, was performed with 1 mol % Ir of the heterogeneous catalyst in water without the use of organic solvents under aerobic conditions to give the corresponding alkylated amines.

Abstract:We report the development of a silicon nanowire array-stabilized palladium nanoparticle catalyst, SiNA-Pd. Its use in the palladium-catalyzed Mizoroki-Heck reaction, the hydrogenation of an alkene, the hydrogenolysis of nitrobenzene, the hydrosilylation of an a,b-unsaturated ketone, and the C-H bond functionalization reactions of thiophenes and indoles achieved a quantitative production with high reusability. The catalytic activity reached several hundred-mol ppb of palladium, reaching a TON of 2 000 000.

A dehydrative alkylation with three kinds of Ir/B heterobimetallic polymeric catalysts in water is reported. The polymeric heterobimetallic catalysts were readily prepared by ionic convolution of a poly(catechol borate) and iridium complexes. The N-alkylation of ammonia and amines with alcohols, as alkylating agents, was carried out with a heterogeneous catalyst (1 mol% Ir) at 100°C without the use of organic solvents under aerobic and aqueous conditions to afford the corresponding alkylated amines in high yield.The dehydrative alkylation of amines and ammonia is an important reaction for organic syntheses although the dehydration in water is a paradox under equilibrium conditions, known as water paradox. 1 Enzymes promote such reactions with extremely high efficiency; for instance, Nmethyltransferases are enzymes for methylation of terminal amines to form N-methylated amines under aqueous conditions. 2 Therefore, development of N-methyltransferase-inspired polymeric metal catalysts for the dehydration system has attracted interest: 3 Especially, a hydrogentransfer dehydrative N-alkylation of amines with alcohols under aqueous conditions provides a fundamental and straightforward synthetic route for the preparation of nitrogen-containing bioactive compounds as well as pharmaceutical molecules, and agrochemicals. 4,5 Alcohols can be utilized as alkylating agents in place of harmful and toxic alkyl halides in the conversion. Several reports have been shown as pioneering studies on the N-alkylation of amines with alcohols by a use of homogeneous catalysts in organic solvents and/or water. 6,7 Recently, Madsen, Milstein, Williams, Fujita, and Yamaguchi and their coworkers reported the interesting alkylation reactions of amines with alcohols in water by utilizing homogeneous catalysts. 8 In contrast, the catalytic system of this reaction under aqueous and heterogeneous 9 catalytic conditions still remains a major challenge. We have reported a novel protocol for the preparation of highly active and reusable polymer-supported catalysts from soluble linear polymer having multiple ligand groups and metal species through the coordinate or ionic complexation, affording insoluble polymer-metal composites. 10 We had an interest in the bimetallic complexation of dicationic iridium species and catechol borate polymer species for constructing heterobimetallic multifunctional catalysts; 11,12 iridium species could work as a cross-linker of borate polymers as well as a catalytic species. Catechol borate polymer species should be not only a main-chain polymer backbone but also a Brønsted base. Herein, we report the full detail of the preparation of several novel convoluted polymeric heterobimetallic catalysts for the hydrogen-transfer dehydrative N-alkylation of amines with alcohols in water. 13 Aqueous ammonia and amines were readily alkylated with alcohols in water under aerobic conditions. Poly(spiroborate)iridium catalysts 3, 3′, and 3′′ were synthesized as follows. A linear catechol borate polymer 1 was prepared from 1,2-dime...