Chiral linear polymers bonded alternatively with salen and 1,4-dialkoxybenzene: synthesis and application for Ti-catalyzed asymmetric TMSCN addition to aldehydes

The synthesis of chiral linear polymers 1a–b having salen and 1,4-dioctyloxybenzene as alternate segments has been accomplished. The GPC analysis showed the molecular weights corresponding to ca. 15 (Mw = 10,999, Mn = 9165 and PDI = 1.20) repeating units for 1a and ca. 8 (Mw = 8547, Mn = 7883 and PDI = 1.08) repeating units for 1b. Polymers 1a–b have been studied with Ti(OiPr)4 as a recyclable catalyst for the asymmetric addition of TMSCN to aldehydes while the selectivity of the polymer catalyst is identical to that of the monomer. The reactions are efficient affording the cyanohydrins with up to 88% ee. The selectivity of the polymer based catalyst 9a is found to be the same to that of the monomer 10a. The reaction provides the advantages of simplified product isolation and easy recovery and recyclability of polymer catalyst 9a without any loss of activity or selectivity

Copper(II)-catalyzed oxidation of alcohols to carbonyl compounds with hydrogen peroxide

Copper(II) complex 1 efficiently catalyses the oxidation of alcohols to the corresponding carboxylic acid analogues and ketones in the presence of H<SUB>2</SUB>O<SUB>2</SUB> in high yields

Role of temperature in [3+2]-cycloaddition of isoselenocyanates with oxiranes using BF<SUB>3</SUB>·Et<SUB>2</SUB>O

The [3+2]-cycloaddition reaction of isoselenocyanates with oxiranes using BF3·Et2O is temperature dependent affording generally either substituted 2-imino-1,3-oxaselenolanes (−5 °C) or 1,3-oxazolidinones (40 °C) in short reaction times with high yields

Preparation of 2-azido-1-substituted-1 H-benzo[d]imidazoles using a copper-promoted three-component reaction and their further conversion into 2-amino and 2-triazolyl derivatives

Multicomponent reaction: 2-Azido-1-substituted-1H-benzo[d]imidazoles were prepared using a copper-catalyzed three-component reaction involving 2-bromoaniline derivatives, isothiocyanates, and sodium azide. The reaction conditions were mild and the scope was broad. The azido compounds were transformed into their 2-amino and 2-triazolyl derivatives using copper-mediated reduction and cycloaddition, respectively (see scheme)

“On water”: efficient iron-catalyzed cycloaddition of aziridines with heterocumulenes

In suspension: The reaction of aziridines with heterocumulenes in the presence of Fe(NO3)3⋅9 H2O in aqueous suspension provides access to functionalized five-membered heterocycles in good to high yields. This protocol has a wide substrate scope, is simple, and uses a nontoxic and cheap catalyst

Fluorescent OFF–ON polymer chemosensor bonded alternatively with 1,4-dioctyloxybenzene and (R,R)-salen for cascade Zn<SUP>2+</SUP> and chiral recognition

The synthesis of the chiral main chain polymers 1a–b bonded alternatively with (R,R)-salen and 1,4-dioctyloxybenzene has been described employing a palladium-catalyzed C–C cross-coupling reaction as the key step. They are soluble in common organic solvents and act as a highly selective ‘OFF–ON’ fluorescent chemosensors toward Zn2+. The resultant Zn(II)-polymer complexes exhibit significant chiral recognition toward (R)- and (S)-1-phenyl-N-[(pyridin-2-yl)methylene]ethanamines 9 under ambient conditions

Effect of ligand N,N-substituents on the reactivity of chiral copper(II) salalen, salan, and salalan complexes toward asymmetric nitroaldol reactions

The synthesis and effect of ligand N,N-substituents on the reactivity of chiral copper(II) salalen, salan, and salalan complexes toward nitroaldol reactions of nitromethane with various aldehydes have been described. The salan complexes exhibit superior results compared to the salalen and salalan complexes; the nature of the N,N-substituents is crucial for the enantioselectivity of the target nitroaldol products

Copper-catalyzed domino one-pot synthesis of 2-(arylselanyl)arylcyanamides

Domino C–Se cross-coupling of 2-(iodoaryl)selenoureas with aryl iodides has been accomplished in the presence of a copper(I)–1,1-phenanthroline complex at moderate temperature. The reactions involve intra- and intermolecular C–Se cross-coupling to give the substituted 2-(arylselanyl)arylcyanamides. Aryl iodides having electron-donating and -withdrawing substituents are compatible, affording the targetselanyl ethers in high yield

Synthesis, structure and catalysis of tetranuclear copper(II) open cubane for Henry reaction on water

The copper(II) open cubane 1 has been synthesized and its structure determined. It is insoluble in water and efficiently catalyzes the Henry reaction with high yield

Silica-supported vanadium-catalyzedn-oxidation of tertiary amines with aqueous hydrogen peroxide

A recyclable silica supported vanadium 1 catalyzes the oxidation of tertiray amines to the corresponding N-oxides with 30% H<SUB>2</SUB>O<SUB>2</SUB> in high yield