We have developed the first example of hypervalent iodine(V)-catalyzed regioselective oxidation of phenols to o-quinones. Various phenols could be oxidized to the corresponding o-quinones in good to excellent yields using catalytic amounts of sodium salts of 2-iodobenzenesulfonic acids (pre-IBSes) and stoichiometric amounts of Oxone® as a co-oxidant under mild conditions. The reaction rate of I...

The reduction process for some quinones has been studid by cyclic voltammeby, rotating disk electrode voltammetry and chronopotentiometry in chloroform at platinum, gold and glassy carbon electrodes using tetrabutylmonium perchlorate (TB AP) as supporting eiectrolyte. The results obtained from this study reveal that the reduction of the quinones is two one-electron processes, the first redu...

the reduction process for some quinones has been studid by cyclic voltammeby, rotating disk electrode voltammetry and chronopotentiometry in chloroform at platinum, gold and glassy carbon electrodes using tetrabutylmonium perchlorate (tb ap) as supporting eiectrolyte. the results obtained from this study reveal that the reduction of the quinones is two one-electron processes, the first reductio...

A convenient two-step method for the synthesis of novel 1,3-benzoxathiol-2-ones and naphtho[2,1-d][1,3]oxathiol-2-ones bearing (1H-tetrazol-1-yl)phenyl motif was developed. As a key step synthesis, an arylation quinones (1,4-benzoquinone, 1,4-naphtho-quinones) with (1H-tetrazol-1-yl)arenediazonium salts studied efficient protocols were elaborated to obtain variety substituted ((1H-tetrazol-1-yl...

Thirteen heterocyclic quinones (5 quinoline quinones, 7 isoquinoline quinones, 1 indole quinone) were tested for their effects on avian myeloblastosis virus reverse transcriptase, growth of murine lymphoblastoma L5178Y cells, respiration of rat liver mitochondria and oxidation of NADH by Clostridium kluyveri diaphorase in comparison with those of streptonigrin, in which the quinoline quinone mo...

From the chloroform extract of the fresh fruits of Diospyros maritima BLUME (Ebenaceae), five new naphthoquinone derivatives, 2,7'-dimethyl-2',3-bijuglone (27), 2,7'-dimethyl-3,3'-bijuglone (28), 2,7'-dimethyl-6,8'-bijuglone (29), 7,7'-dimethyl-3,3'-ethylidenebijuglone (30), and 2',7-dimethyl-3,6'-ethylidenebijuglone (31), were isolated, in addition to twenty-one known naphthoquinone derivative...

The cytotoxic and antiproliferative properties of many natural sesquiterpene-quinones and -hydroquinones from sponges offer promising opportunities for the development of new drugs. A review dealing with different strategies for obtaining bioactive terpenyl quinones/hydroquinones is presented. The different synthetic approches for the preparation of the most relevant quinones/hydroquinones are ...

Bacteriochlorophyll (BChl) c is the main constituent of chlorosomes, the light harvesting complexes of green photosynthetic bacteria, where it is found in the form of aggregates. Similar aggregates can be prepared also in vitro. In this study we show that the aggregation of BChl c in aqueous buffers can be induced by quinones possessing a hydrophobic tail. Such quinones are naturally present in...

1. The reactions of amino acids and peptides with the o-quinones produced by the enzymic oxidation of chlorogenic acid and caffeic acid have been studied manometrically and spectrophotometrically. 2. Amino acids, except lysine and cysteine, react primarily through their alpha-amino groups to give red or brown products. These reactions, which compete with the polymerization of the quinones, are ...

Polycyclic aromatic hydrocarbons (PAH) are ubiquitous environmental pollutants. They are procarcinogens requiring metabolic activation to elicit their deleterious effects. Aldo-keto reductases (AKR) catalyze the oxidation of proximate carcinogenic PAH trans-dihydrodiols to yield electrophilic and redox-active PAH o-quinones. AKRs are also found to be capable of reducing PAH o-quinones to form P...