Direct Amination of Arenes with Azodicarboxylates Catalyzed by Bisulfate Salt/HFIP Association

Metal-free C(sp3)-H functionalization (C-C and C-N bond formation) of 1,2,3,4-tetrahydroacridines using deep eutectic solvents as catalyst and reaction medium

Herein, we report a metal-free and efficient method for the C(sp3)-H functionalization of 1,2,3,4-tetrahydroacridines at the C4-position by the addition of azodicarboxylates (C-N bond) and maleimides (C-C bond) using deep eutectic solvents (DESs) at 80 °C. The C4-functionalized 1,2,3,4-tetrahydroacridines were achieved with high atom efficiency, precise regioselectivity, and yields ranging from 70-96%. The practicality of the developed method has been demonstrated through gram-scale synthesis. Also the green-metrics were calculated for the developed method and it was found that the metrics are near to the ideal values.

Sustainable Organic Photocatalysis for Site-Selective Hydrazocoupling of Electron-Rich Arenes

An efficient photocatalytic para- and ortho-selective amination and aminative dearomatization of phenols, naphthols, and anilines with azodicarboxylates was developed using riboflavin tetraacetate (RFTA) as an organic photocatalyst. The site selectivity was controlled using tetrabutylammonium bromide (TBAB), which also acts as a phase transfer catalyst. The reaction conditions are simple and mild, giving high regioselectivity with good to excellent yields. A broad substrate scope and nice functional group tolerance with scalability and post-functionalization make this protocol both useful and regioselective.

HFIP in Organic Synthesis

1,1,1,3,3,3-Hexafluoroisopropanol (HFIP) is a polar, strongly hydrogen bond-donating solvent that has found numerous uses in organic synthesis due to its ability to stabilize ionic species, transfer protons, and engage in a range of other intermolecular interactions. The use of this solvent has exponentially increased in the past decade and has become a solvent of choice in some areas, such as C-H functionalization chemistry. In this review, following a brief history of HFIP in organic synthesis and an overview of its physical properties, literature examples of organic reactions using HFIP as a solvent or an additive are presented, emphasizing the effect of solvent of each reaction.

Repurposing Mitsunobu Reactions as a Generic Approach toward Polyethylene Derivatives

Broad scope of functionality and controllable degree of functionalization are intriguing goals for the development of polar-group-functionalized polyethylene materials. Herein, we propose a generic strategy of using widely available starting materials (i.e., poly(ethylene-co-vinyl acetate), EVA) and mild Mitsunobu functionalization conditions to prepare over 30 polyethylene derivatives. No noble transition metal catalysts (e.g., Ru, Mo, Pd, etc.) or corrosive/explosive reagents (e.g., HBr, NaN₃, C₂H₄, H₂, etc.) are used in the synthesis, while functional groups such as azide, aldehyde, norbornene, and thiol can be easily installed, with tunable content as high as 18 mol %. Using this practical method, we successfully prepared polyethylene-derivatized membranes with excellent antimicrobial and fluorescent properties.

Highly selective electrophilic B(9)-amination of o-carborane driven by HOTf and HFIP

An efficient B(9) electrophilic amination of o-carboranes with azodicarboxylates, promoted by a Brønsted acid and HFIP, was developed.

Silver-Catalyzed para-Selective Amination and Aminative Dearomatization of Phenols with Azodicarboxylates in Water

An efficient silver-catalyzed para-selective amination and aminative dearomatization of phenols with azodicarboxylates was developed. It afforded the para-aminophenols or amino cyclohexadieneones from free phenols depending on whether it has a para-substituent. The reaction proceeded smoothly in water under simple and mild conditions, giving the highly selective products in good yields within a short reaction time. It also showed broad substrate scope and good functional group compatibility.

Aerobically-initiated C(sp3)–H bond amination through the use of activated azodicarboxylates

In this article we report a procedure for α-C(sp³)–H amination of ethereal compounds through use of azodicarboxylates as the nitrogen source and freely-available atmospheric oxygen to access ethereal radical intermediates via aerobic C–H activation.