Cu(II)-catalyzed aerobic hydroperoxidation of Meldrum's acid derivatives and application in intramolecular oxidation: a conceptual blueprint for O2/H2 dihydroxylation

Donor-Acceptor Cyclopropanes: Activation Enabled by a Single, Vinylogous Acceptor

A novel class of highly activated donor-acceptor cyclopropanes bearing only a single, vinylogous acceptor is presented. These strained moieties readily undergo cycloadditions with aldehydes, ketones, thioketones, nitriles, naphth-2-ols and various other substrates to yield the corresponding carbo- and heterocycles. Diastereocontrol can be achieved through the choice of catalyst (Brønsted or Lewis acid). The formation of tetrahydrofurans was shown to be highly enantiospecific when chiral cyclopropanes are employed. A series of mechanistic and kinetic experiments was conducted to elucidate a plausible catalytic cycle and to rationalize the stereochemical outcome.

Structural basis for endoperoxide-forming oxygenases

Endoperoxide natural products are widely distributed in nature and exhibit various biological activities. Due to their chemical features, endoperoxide and endoperoxide-derived secondary metabolites have attracted keen attention in the field of natural products and organic synthesis. In this review, we summarize the structural analyses, mechanistic investigations, and proposed reaction mechanisms of endoperoxide-forming oxygenases, including cyclooxygenase, fumitremorgin B endoperoxidase (FtmOx1), and the asnovolin A endoperoxygenase NvfI.

Bioinspired radical cyclization of tryptamines: synthesis of peroxypyrroloindolenines as potential anti-cancer agents

Inspired by the heme iron-catalyzed radical insertion of dioxygen to the tryptophan indole ring, herein we utilize alkylperoxy radical species as a coupling partner to trigger a peroxycyclization of readily accessible tryptophan derivatives and enable the first synthesis of peroxypyrroloindolenines.

Catalytic Halogen Bond Activation in the Benzylic C-H Bond Iodination with Iodohydantoins

This letter presents the side-chain iodination of electron-deficient benzylic hydrocarbons at rt using N-hydroxyphthalimide (NHPI) as radical initiator and 1,3-diiodo-5,5-dimethylhydantoin and 3-iodo-1,5,5-trimethylhydantoin (3-ITMH) as iodine source. Addition of a carboxylic acid increased the reactivity due to complex formation with and activation of 3-ITMH by proton transfer and halogen bond formation. No S_EAr reactions were observed under the employed reaction conditions. Our method enables convenient product isolation and gives 50-72% yields of isolated products.

Advances in the synthesis of acyclic peroxides

This review summarises the many developments in the synthesis of acyclic peroxides, with a particular focus on the past 20 years, and seeks to update organic chemists about these new approaches.

Synthesis of 2-hydroxymalonic acid derivatives via tandem oxidation and rearrangement by photo organic catalysis

This report describes a mild method for the direct transformation of β-oxoesters to the corresponding tartronic esters using singlet oxygen produced by a catalytic amount of methylene blue and visible light irradiation using fluorescent lamps.

Systemic study on the biogenic pathways of yezo’otogirins: total synthesis and antitumor activities of (±)-yezo’otogirin C and its structural analogues

A systematic study of the biomimetic pathways to yezo’otogirin C under aerobic and anaerobic conditions has been investigated, and both are found to be feasible pathways to the natural product depending on the physiological conditions. Because of the lower activation energy, the aerobic process would be more favorable when the in vivo oxygen level is high. In the course of this study, a highly efficient synthetic route to (±)-yezo’otogirin C has been established in four steps (31% overall yield) from a readily available compound without using any protecting groups. The natural product and its structural analogues exhibited antitumor activities against several human cancer cell lines and appeared to arrest cell cycles in different phases.

Synthesis of α-peroxyesters via organocatalyzed O-H insertion of hydroperoxides and aryl diazoesters

The synthesis of α-aryl peroxyesters, an unprecedented class of organic peroxide, via hydrogen-bond donor catalyzed O-H insertions of hydroperoxides and α-aryl diazoesters is reported. The method is applicable to a diverse set of substrates and the corresponding α-peroxyesters are typically isolated in high yield. Both thermogravimetric analysis and reactions with traditional peroxide reducing agents demonstrate the stability of α-peroxyesters.

Cyclization-endoperoxidation cascade reactions of dienes mediated by a pyrylium photoredox catalyst

Triarylpyrylium salts were employed as single electron photooxidants to catalyze a cyclization-endoperoxidation cascade of dienes. The transformation is presumed to proceed via the intermediacy of diene cation radicals. The nature of the diene component was investigated in this context to determine the structural requirements necessary for successful reactivity. Several unique endoperoxide structures were synthesized in yields up to 79%.