3-Substituted 2-isocyanopyridines as versatile convertible isocyanides for peptidomimetic design.

We report the use of 3-substituted 2-isocyanopyridines as convertible isocyanides in Ugi four-component reactions. The N-(3-substituted pyridin-2-yl)amide Ugi products can be cleaved by amines, alcohols, and water with Zn(OAc)2 as a catalyst. In addition, the applicability of the method was demonstrated in constrained di-/tripeptides bearing acid and base sensitive protective groups obtained via Ugi-4CR post-condensation modifications.

Carbamate Synthesis Using a Shelf-Stable and Renewable C1 Reactant.

4-Propylcatechol carbonate is a shelf-stable, renewable C1 reactant. It is easily prepared from renewable 4-propylcatechol (derived from wood) and dimethyl carbonate (derived from CO2 ) using a reactive distillation system. In this work, the 4-propylcatechol carbonate is used for the two-step synthesis of carbamates under mild reaction conditions. In the first step, 4-propylcatechol carbonate is treated with an alcohol at 50-80 °C in the presence of a Lewis acid catalyst, such as Zn(OAc)2 ⋅2 H2 O. With liquid alcohols, no solvent is used and with solid alcohols 2-methyltetrahydrofuran is used as solvent. In the second step, the alkyl 2-hydroxy-propylphenyl carbonate intermediates obtained react with amines at room temperature in 2-methyltetrahydrofuran, forming the target carbamates and the byproduct 4-propylcatechol, which can be recycled into a carbonate reactant.

Ruthenium-Catalyzed Reductive Arylation of N-(2-Pyridinyl)amides with Isopropanol and Arylboronate Esters.

A new three-component reductive arylation of amides with stable reactants (iPrOH and arylboronate esters), making use of a 2-pyridinyl (Py) directing group, is described. The N-Py-amide substrates are readily prepared from carboxylic acids and PyNH2 , and the resulting N-Py-1-arylalkanamine reaction products are easily transformed into the corresponding chlorides by substitution of the HN-Py group with HCl. The 1-aryl-1-chloroalkane products allow substitution and cross-coupling reactions. Therefore, a general protocol for the transformation of carboxylic acids into a variety of functionalities is obtained. The Py-NH2 by-product can be recycled.

New metal extractants and super-acidic ionic liquids derived from sulfamic acid.

Sulfamic acid (NH3-SO3) is an acidic zwitterion with many applications. N-Alkylated derivatives are introduced, which can be used as a new class of metal extractants R2NH-SO3 and as new super-acidic ionic liquids [R2NH-SO3H][Tf2N]. The synthesis, properties and novel applications of this versatile platform are discussed.

Alkylsulfuric acid ionic liquids: a promising class of strongly acidic room-temperature ionic liquids.

Strongly acidic (pKa ≈ -3.5) room-temperature ionic liquids (ILs) with -OSO3H functionalized cations are introduced. The strong acidity, easy synthesis, and better physical properties of these R-OSO3H ILs make them excellent alternatives to the well-known sulfonic acid (R-SO3H) ILs, especially in the domain of metal processing.