Efficient One-Pot Tandem Catalysis of Glucose into 1,1,2-Trimethoxyethane over W-Beta Catalyst

One-pot efficient transformation of glucose to 1,1,2-trimethoxyethane via epimerization, retro-aldol condensation (RAC), acetalization, and etherification processes over W-Beta catalyst in methanol phase was proposed. Uniform dispersive 0.5 wt% tungsten species...

Compartmentalisation of molecular catalysts for nonorthogonal tandem catalysis

The development of nonorthogonal tandem catalysis enables the use of a combination of arbitrary catalysts to rapidly synthesize complex products in a sustainable, efficient, and timely manner.

Asymmetric Synthesis of Propargylic alfa-Chiral Tertiary Amines by Reductive Alkynylation of Tertiary Amides Using Ir/Cu Tandem Catalysis

The development of an asymmetric protocol for the reductive alkynylation of amides to access important alfa-chiral tertiary propargylic amines is reported using tandem Ir-catalyzed hydrosilylation/enantioselective Cu-catalyzed alkynylation. The reaction utilizes a Cu/PyBox catalyst system in the alkynylation step to achieve asymmetry and affords excellent yields with moderate to good levels of enantiocontrol while employing low Ir-catalyst loadings (0.5 mol %).

Tandem electrocatalytic N2 fixation via concerted proton-electron transfer

New electrochemical ammonia (NH3) synthesis technologies are of interest as a complementary route to the Haber-Bosch (HB) process for distributed fertilizer generation, and towards exploiting ammonia as a zero-carbon fuel produced via renewably-sourced electricity.1–4 Apropos of these goals is a surge of fundamental research targeting heterogeneous materials5–7 as electrocatalysts for the nitrogen reduction reaction (N2RR). These systems generally suffer from poor stability and NH3 selectivity; competitive hydrogen evolution reaction (HER) outcompetes N2RR.8 Molecular catalyst systems can be exquisitely tuned and offer an alternative strategy,9 but progress has thus far been thwarted by the same selectivity issue; HER dominates. Herein we describe a tandem catalysis strategy that offers a solution to this puzzle. A molecular complex that can mediate an N2 reduction cycle is partnered with a co-catalyst that interfaces the electrode and an acid to mediate concerted proton-electron transfer (CPET) steps, facilitating N−H bond formation at a favorable applied potential and overall thermodynamic efficiency. Without CPET, certain intermediates of the N2RR cycle would be unreactive via independent electron transfer (ET) or proton transfer (PT) steps, thereby shunting the system. Promisingly, complexes featuring several metals (W, Mo, Os, Fe) achieve N2RR electrocatalysis at the same applied potential in the presence of the CPET mediator, pointing to the generality of this tandem approach.

Iridium/Graphene Nanostructured Catalyst for the N-Alkylation of Amines to Synthesize Nitrogen-containing Derivatives and Heterocyclic Compounds

A facile iridium/graphene-catalyzed methodology providing an efficient synthetic route for C-N bond formation is reported. This catalyst can directly promote the formation of C-N bonds, without pre-activation steps, and without solvents, alkalis and other additives. This protocol provides a direct N -alkylation of amines using a variety of primary and secondary alcohols with good selectivity and excellent yields. Charmingly, the use of diols resulted in intermolecular cyclization of amines, and such products are privileged structures in biologically active compounds. Two examples illustrate the advantages of this catalyst in organic synthesis: the tandem catalysis to synthesize hydroxyine, and the intermolecular cyclyzation to synthesize cyclizine. Water is the only by-product, which makes this catalytic process sustainable and environmentally friendly.