A novel quinoline-based NNN-pincer Cu(II) complex as a superior catalyst for oxidative esterification of allylic C(sp3)-H bonds

We report for the first time that the quinoline-based NNN-pincer Cu(II) complex acts as an air stable superior catalyst for the oxidative cross-coupling of the allyl sp³ C-H bond with an acid for the synthesis of allyl esters in a homogeneous system at ambient temperature. The synthesized catalyst, 1, has been well characterized by various analytical techniques (HRMS, single crystal X-ray diffraction, CV, EPR, UV-vis spectroscopy) and showed excellent catalytic activity for the oxidative esterification of allylic C(sp³)-H bonds at 40 °C within a very short period of time (1 h) using only 1 mol% of the catalyst. A wide variety of aromatic allylic esters were synthesized in moderate to good yields, which could be extended to aliphatic allyl esters as well.

Oxidative α-acyloxylation of acetals with cyclic diacyl peroxides

Selective functionalization of the non-activated acetal α-position with formal retaining of the acetal fragment was realized using cyclic diacyl peroxides.

C(sp3)–H Bond Functionalization of Alcohols, Ketones, Nitriles, Ethers and Amides using tert-Butyl Hydroperoxide as a Radical Initiator

The C(sp3)–H bond is found widely in organic molecules. Recently, the functionalization of C(sp3)–H bonds has developed into a powerful tool for augmenting highly functionalized frameworks in organic synthesis. Based on the results obtained in our group, the present account mainly summarizes recent progress on the functionalization of C(sp3)–H bonds of aliphatic alcohols, ketones, alkyl nitriles, and ethers with styrene or cinnamic acid using tert-butyl hydroperoxide (TBHP) as a radical initiator.

1 Introduction

2 Oxidative Coupling of Styrenes with C(sp3)–H Bonds

3 Decarboxylative Cross-Couplings of α,β-Unsaturated Carboxylic Acids with C(sp3)–H Bonds

4 Conclusions

Recent methods for the synthesis of α-acyloxy ketones

The present review provides a broad description of the methods reported for the synthesis of α-acyloxy ketones and some of their derivatives.

ATRA-like alkylation–peroxidation of alkenes with trichloromethyl derivatives by the combination of tBuOOH and NEt3

This protocol provides a unique and innovative approach to the construction of α-tert-butylperoxy-β-dichloromethyl alkanes, employing CHCl₃ as an alkylating reagent to provide a –CHCl₂ group, and TBHP as an oxidant to provide an α-^tBuOO group.

Copper-catalyzed α-C–H acyloxylation of carbonyl compounds with terminal alkynes

Herein, a copper/TBHP catalyst system for the α-C–H acyloxylation of carbonyl compounds is developed using terminal alkynes as the acyloxy source.

Synthesis ofN-sulfenyl-sulfoximines and -sulfenamides through a metal-free N–H/S–H dehydrocoupling reaction

A metal-free, iodine-catalyzed N–H/S–H dehydrocoupling reaction of sulfoximines and anilines with various thiols to construct sulfur–nitrogen bonds has been developed.

Difunctionalization of alkenes with iodine and tert-butyl hydroperoxide (TBHP) at room temperature for the synthesis of 1-(tert-butylperoxy)-2-iodoethanes

We developed a direct vicinal difunctionalization of alkenes with iodine and TBHP at room temperature. This iodination and peroxidation in a one-pot synthesis produces 1-(tert-butylperoxy)-2-iodoethanes, which are inaccessible through conventional synthetic methods. This method generates multiple radical intermediates in situ and has excellent regioselectivity, a broad substrate scope and mild conditions. The iodine and peroxide groups of 1-(tert-butylperoxy)-2-iodoethanes have several potential applications and allow further chemical modifications, enabling the preparation of synthetically valuable molecules.

α-Acetoxyarone synthesis via iodine-catalyzed and tert-butyl hydroperoxide-mediateded self-intermolecular oxidative coupling of aryl ketones

We present a metal-free method for α-acetoxyarone synthesis by self-intermolecular oxidative coupling of aryl ketones using I₂−tert-butyl hydroperoxide (TBHP). Under the optimum conditions, various aryl ketones gave the corresponding products in moderate to excellent yields. A series of control experiments were performed; the results suggest the involvement of radical pathways. Multiple radical intermediates were generated in situ and the overall process involved several different reactions, which proceeded self-sequentially in a single reactor. A labeling experiment using ¹⁸O-labeled H₂O confirmed that the oxygen in the product was derived from TBHP, not from H₂O in the TBHP solvent.

nBu4NI-catalyzed oxidative cross-coupling of carbon dioxide, amines, and aryl ketones: access to O-β-oxoalkyl carbamates

The first nBu₄NI-catalyzed oxidative cross-coupling reaction of carbon dioxide, amines and arylketones leading to O-β-oxoalkyl carbamates is reported.

Aerobic copper catalyzed α-oxyacylation of ketones with carboxylic acids

A copper catalyzed direct α-oxyacylation of ketones with carboxylic acids under air conditions has been developed.

KI-catalyzed α-acyloxylation of acetone with carboxylic acids

A KI catalyzed reaction of acetone with aromatic carboxylic acids is achieved, leading to α-acyloxycarbonyl compounds in good to excellent yields under mild reaction conditions. The present method exhibits good functional-group compatibility.

Novel and efficient transformation of enamides into α-acyloxy ketones via an acyl intramolecular migration process

Hydrogen peroxide and anhydride mediated transformation of enamides to afford substituted α-acyloxy ketones is described.

NBS/DBU mediated one-pot synthesis of α-acyloxyketones from benzylic secondary alcohols and carboxylic acids

A simple and efficient NBS/DBU-mediated one-pot procedure has been developed for the synthesis of α-acyloxyketones from benzylic secondary alcohols and carboxylic acids.

Synthesis of esters via sp3 C–H functionalisation

This review describes various methods for the synthesis of eleven classes of esters involving sp³ C–H functionalisation.