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Reactions of N,N`-disubstituted hydrazinecarbothioamides 8a-c and substituted thioureidoethylthioureas 9a-c with 2,3,5,6-tetrachloro-1,4-benzoquinone (chloranil, 10a) and 2,3,5,6-tetrabromo-1,4-benzoquinone (bromanil, 10b) to form N,N`-disubstituted [1,3,4]thiadiazole-2,5-diamines 11a-c, 6,7-dichloro-3-substituted amino-1H-benzo[1,3,4]- thiadiazine-5,8-diones 12a-c, 2,3,7,8-tetrahalothianthrene-1,4,6,9-tetraones 13a,b, 5,6,8- trihalo-7-oxo-3,7-dihydro-2H-quinoxaline-1-carbothioic acid substituted amides 14a-c, 15a-c and 7-substituted imino-[1,3,6]thiadiazepane-3-thiones 16a-c are reported. Rationales for the observed conversions are presented.

The unique electronic and structural characteristics of 1,4-benzoquinones with possibilities for numerous interactions such as coordination, hydrogen bonding accompanied by proton and/or electron transfer, p-interactions, and redox activity, are used by nature to perform important biological reactions. In spite of their wide use in supramolecular chemistry for construction of functional materials, the intercorrelation of their versatile interactions has not been completely evaluated. The impacts of hydrogen bonding and cations on interactions of quinoid skeleton are studied on the prepared series of alkali (Li+, Na+, K+, NH4+ , and Rb+ ) chloranilate hydrates, and anhydrous caesium homologue. The π…π stacking interactions of chloranilate dianions observed in the structures of sodium chloranilate dihydrate and caesium sodium chloranilate monohydrate [with centroid separation distances of 3.662(1) and 3.740(2) Å and shifts of 1.698 and 1.358 Å, respectively] are tuned by hydrogen bonding involving water molecules. The crystal structures of potassium and rubidium chloranilate monohydrates are isostructural whereas their ammonium homologue, due to the presence of cation with pronounced proton-donor activity, exhibits completely different hydrogen bonding network. In the six of seven structures studied chloranilate dianion reveals the crystallographic symmetry Ci. [ABSTRACT FROM AUTHOR]

Abstract: The manganese(III) initiated oxidative free radical reactions of 2-amino-1,4-benzoquinone are described. The free radical reaction of 5,6-dimethyl-2-methylamino-1,4-benzoquinone (1) provides a novel method for the synthesis of indole-4,7-dione and indole-2,4,7-trione. High chemoselectivity was observed in different solvents. The regioselectivity of this reaction was also studied with 5-methyl-2-methylamino-1,4-benzoquinone (19). In most cases, indole-4,7-diones 20 and 21 were produced in high regioselectivity. [Copyright &y& Elsevier]

Abstract: Alkylated phenol and methoxytoluene derivatives were catalytically and selectively oxidized to the corresponding 1,4-benzoquinones in good conversions and yields. Reactions were performed with hydrogen peroxide (H2O2)/methyltrioxorhenium (CH3ReO3) in 1-butyl-3-methylimidazolium tetrafluoroborate [bmim]BF4, a neutral ionic liquid. Compounds were tested in vitro for their antifungal activity against the growth of several widespread soil fungi. Some of them were proved to be potent inhibitors of Fusarium sp. than ketoconazole, a commercially available and expensive antifungal agent. [Copyright &y& Elsevier]

Abstract: From the dichloromethane extract of the leaves and stems of Gunnera perpensa two new, simple 1,4-benzoquinones and a known benzopyran-6-ol were isolated. From the methanol extract phytol was obtained. The two benzoquinones, 2-methyl-6-(-3-methyl-2-butenyl)benzo-1,4-quinone (1) and 3-hydroxy-2-methyl-5-(3-methyl-2-butenyl)benzo-1,4-quinone (2) and the benzopyran, 6-hydroxy-8-methyl-2,2-dimethyl-2H-benzopyran (3) were examined for antimicrobial properties together with the crude stem, leaf and root extracts. Minimum inhibitory concentration (MIC) assays were used to quantify antimicrobial activity and the MIC values for the crude extracts of stems, roots and leaves ranged between 100μg and >16mg/ml against the eight microorganisms investigated. Compound 1 showed significant antimicrobial activity with the most sensitive organism being Staphylococcus epidermidis with an MIC of 9.8μg/ml. For compound 2, no activity was noted. Compound 3 exhibited good activity against the yeasts Cryptococcus neoformans (75μg/ml) and Candida albicans (37.5μg/ml). [Copyright &y& Elsevier]

Abstract: o-Quinone methides are formed from the reaction of nucleophiles with trimethylsilyl(methyl)-1,4-benzoquinones. These reactive intermediates are trapped by excess nucleophile to form substituted quinones following oxidation. In addition, varying amounts of a symmetrical dimer and a xanthen derivative were observed. The influence of different nucleophiles and ring substituents on the rate of reaction have been studied, and are consistent with rate-limiting formation of a vinylogous enolate initiated by attack of the nucleophile on the silyl group. [Copyright &y& Elsevier]