Copper-Catalyzed Aerobic Oxidative Cleavage of C–C Bonds in Epoxides Leading to Aryl Ketones

Dual Oxidation of Epoxides with a High-Valent Cu(III)-CF3 Compound and DMSO to Access 1,2-Diketones

This study reports sequential dehydrogenation and transfer oxygenation of 1,2-diarylepoxides by high-valent phenCu(III)(CF3)3 and DMSO to produce 1,2-diketones. The Cu(III)-CF3 compound serves as a CF3 radical source to abstract the hydrogen atom of the epoxide ring. The resulting ether α-carbon radical undergoes ring-opening rearrangement to give a ketone α-carbon radical intermediate, which is oxygenated by DMSO with the release of Me2S. The combination of a Cu(III)-CF3 compound and DMSO may be exploited to develop other novel oxidation reactions.

Selective Oxidative Cleavage of the C-C Bond in α,β-Epoxy Ketone into Carbonyl Compounds

This method afforded aromatic carbonyl compounds under TBHP via selective oxidative cleavage of the C-C bond in α,β-epoxy ketones. Aromatic acid came from the aroyl section, and aromatic aldehyde came from the other aromatic group. TBHP acted as a free radical initiator and oxidant. The reaction within the solvent went through a ring-opening addition, cleavage of the C-C bond in the ethylene oxide section, and oxidation, affording the target compounds in moderate to good yields. The HPLC yield of aromatic aldehyde was up to 91%. The HPLC yield of aromatic acid was up to 99%. The reaction under solvent-free conditions gave two kinds of aromatic acids coming from different moieties of α,β-epoxy ketone via the further oxidation of aromatic aldehyde. The substituent effect was discussed, and the reaction mechanism was proposed. This method allowed the reaction to occur in a simple system metal-free.

A Zn(II)-Coordination Polymer for the Instantaneous Cleavage of Csp3-Csp3 Bond and Simultaneous Reduction of Ketone to Alcohol

Two coordination polymers of Zn(II) and Cu(II) with n-butylmalonic acid have been achieved in this work. The crystallographic structural descriptions along with the sedimentary rock-type microstructural morphology of these two coordination polymers (CPs) have been explored. The reactivity of β-hydroxy ketones with these two CPs has also been investigated. The Zn(II)-CP shows a specific reactivity with β-hydroxy ketone at room temperature and in open air conditions. Through a microcolumn-based filtration technique, the Zn(II)-CP shows the capability to break the C_sp³-C_sp³ σ bonds of β-hydroxy ketone and simultaneously reduce the associated ketone to alcohol. Such conversion has been progressed without the use of any additional external reducing agent and any chemical workup or column chromatographic purification protocol. Other similar type CPs of Cu(II) and Mn(II) with n-butylmalonic acid completely failed to show similar reactivity with β-hydroxy ketone. On the basis of much experimental evidence, the most possible mechanistic pathway of the reactivity between β-hydroxy ketone and Zn(II)-CP has also been proposed through this work.

Capturing the Organic Species Derived from the C-C Cleavage and in Situ Oxidation of 1,2,3,4-Tetra(pyridin-4-yl)cyclobutane by [CuCN] n-Based MOFs

The solvothermal cycloreversion and in situ oxidation of 1,2,3,4-tetra(pyridin-4-yl)cyclobutane (tpcb) within [CuCN] _n-based MOFs were investigated. The radical mechanism for the cycloreversion of tpcb ligands was supported by capturing a 1,3-butadiene species 1,2,3,4-tetra(4-pyridyl)-1,3-butadiene (tpyb) into {[Cu₁₈(μ-CN)₁₈(tpcb)₄(tpyb)₂]·H₂O} _n in the presence of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO). Without TEMPO, a furan-based ligand 2,3,4,5-tetra(4-pyridyl)furan (tpyf) was generated within {[Cu₄(μ-CN)₄(tpyf)]·4MeCN} _n via the C-C cleavage, followed by in situ oxidation in acidic condition.

Rhodium-catalyzed decarbonylative cycloadditions of 1H-indene-1,2,3-triones and alkynes via direct C–C bond activation: divergent synthesis of indenones and quinones

A one-step preparation method for indenone and quinone derivatives via rhodium-mediated [5 + 2 − 2] and [5 + 2 − 1] decarbonylative cycloadditions of 1H-indene-1,2,3-triones and alkynes has been achieved.

Copper-catalyzed oxidative amidation of α,β-unsaturated ketones via selective C–H or C–C bond cleavage

The copper-catalyzed oxidative amidation of α,β-unsaturated ketones with N-fluorobenzenesulfonimide (NFSI) via a highly regioselective cleavage of C(CO)–C(vinyl) or C(vinyl)–H bonds of ketones has been achieved.

One-Pot Synthesis of Arylketones from Aromatic Acids via Palladium-Catalyzed Suzuki Coupling

A palladium-catalyzed one-pot procedure for the synthesis of aryl ketones has been developed. Triazine esters when coupled with aryl boronic acids provided aryl ketones in moderate to excellent yields (up to 95%) in the presence of 1 mol % Pd(PPh3)2Cl2 for 30 min.

Iron-catalyzed aerobic oxidative cleavage of the C–C σ-bond using air as the oxidant: chemoselective synthesis of carbon chain-shortened aldehydes, ketones and 1,2-dicarbonyl compounds

An efficient iron-catalyzed aerobic oxidative cleavage of the C–C bond to generate a number of carbon-shortened carbonyl compounds.

C-H hydroxylation of phosphonates with oxygen in [bmIm]OH To produce quaternary α-hydroxy phosphonates

A highly efficient and mild [bmIm]OH-catalyzed α-hydroxylation of phosphonates using O2 as the oxygen source is described. The employment of ionic liquid under mild reaction conditions makes this transformation green and practical. Especially, this reaction provided a novel and convenient methodology for the construction of quaternary α-hydroxy phosphonates.

Copper-catalyzed aerobic oxidative cleavage of C–C bonds in epoxides leading to aryl nitriles and aryl aldehydes

Novel copper-catalyzed aerobic synthesis of aryl nitriles and aldehydes from epoxides via C–C single bond cleavage has been discovered.

Nickel N-heterocyclic carbene-catalyzed cross-coupling reaction of aryl aldehydes with organozinc reagents to produce aryl ketones

The transformation of aromatic aldehydes into aryl ketones by nickel-catalyzed cross-coupling has been developed. This transformation represents an efficient and attractive synthetic utilization of organozinc reagents.

The catalytic aerobic synthesis of quaternary α-hydroxy phosphonates via direct hydroxylation of phosphonate compounds

A highly efficient Cu-catalyzed direct hydroxylation of phosphonate compounds has been developed. This transformation provides a powerful method for the synthesis of quaternary α-hydroxy phosphonates in good yields.