A New Method for the Synthesis of 2-Substituted Benzoxazoles from 2-Nitrophenol Derivatives and Aldehydes

Benzoxazole derivatives are one of the compounds with many interesting biological activities. Conventional methods are often performed under complex conditions using strong acids, expensive metal catalysts, requiring high pressure, high temperature, and under microwave irradiation. In this study, we reported a new method of benzoxazole synthesis with redox catalyst using FeCl3.6H2O and sulfur. This is a suitable, efficient, readily available and environmentally friendly catalyst system for redox and condensation reactions in one step at 100 oC. Applying this new method, we have synthesized eight 2-arylbenzoxazole derivatives with high yields (calculated according to 2-nitrophenol). This research is an important step forward in the synthesis of biologically active compounds containing the benzoxazole framework from readily available starting materials in a single reaction.

TBAI Catalyzed Electrochemical C-H Bond Activation of 2-arylated-N-methoxyamides for the Synthesis of Phenanthridinones

An electrochemical method for the synthesis of phenanthridinones via constant potential electrolysis (CPE) mediated by <i>n</i>-Bu₄NI (TBAI) has been reported. The protocol is metal and oxidant free and proceeds with 100% current efficiency. Here TBAI plays the dual role of the redox catalyst as well as supporting electrolyte. The intramolecular C-H activation proceeds under mild reaction conditions and short reaction time via electrochemically generated amidyl radicals. The reaction has been scaled up to gram level showing its practicability and the synthetic utility and applicability of the protocol has been demonstrated by the direct one-step synthesis of the bioactive compound Phenaglaydon.

A tailored multi-functional catalyst for ultra-efficient styrene production under a cyclic redox scheme

Styrene is an important commodity chemical that is highly energy and CO2 intensive to produce. We report a redox oxidative dehydrogenation (redox-ODH) strategy to efficiently produce styrene. Facilitated by a multifunctional (Ca/Mn)1−xO@KFeO2 core-shell redox catalyst which acts as (i) a heterogeneous catalyst, (ii) an oxygen separation agent, and (iii) a selective hydrogen combustion material, redox-ODH auto-thermally converts ethylbenzene to styrene with up to 97% single-pass conversion and >94% selectivity. This represents a 72% yield increase compared to commercial dehydrogenation on a relative basis, leading to 82% energy savings and 79% CO2 emission reduction. The redox catalyst is composed of a catalytically active KFeO2 shell and a (Ca/Mn)1−xO core for reversible lattice oxygen storage and donation. The lattice oxygen donation from (Ca/Mn)1−xO sacrificially stabilizes Fe3+ in the shell to maintain high catalytic activity and coke resistance. From a practical standpoint, the redox catalyst exhibits excellent long-term performance under industrially compatible conditions.

Switching between mono- and doubly-reduced odd alternant hydrocarbon: Designing redox catalyst

Since the early Hückel molecular orbital (HMO) calculations in 1950, it is well known that the odd alternant hydrocarbon (OAH), phenalenyl (PLY) system can exist in three redox states: closed...

Visible Light Mediated Selective Oxidation of Alcohols and Oxidative Dehydrogenation of N-Heterocycles Using Scalable and Reusable La-Doped NiWO4 Nanoparticles

Visible light-mediated selective and efficient oxidation of various primary/secondary benzyl alcohols to aldehydes/ketones and oxidative dehydrogenation (ODH) of partially saturated heterocycles using scalable and reusable heterogeneous photo redox catalyst in...