2.3- Dichloro-5,6-dicyanoquinone

The kinetics for the oxidation of leuco bases using oxygen has been studied.19 The oxidation involves complex formation between the proto-nated leuco base and the peroxy radical formed by air oxidation of the solvent. Addition of a radical initiator (AIBN) facilitates the reaction, while radical inhibitors retard the dye formation. In addition, oxidation reactions employing 2,3-dichloro-5,6-dicyanoquinone have shown large isotope effects in acetonitrile.20... 

Catalytic hydrogenation of the chloro substituted starting material (103) over palladium on carbon gives the dechlorinated and hydrogenated product (109) (68JHC53). 3,4-Dihy-dropyrazino[2,3-d]pyridazines can be dehydrogenated either with 2,3-dichloro-5,6-dicyanoquinone or potassium ferricyanide (75CPB1505). 

Ethylphenol and 2,3-dichloro-5,6-dicyanoquinone in equimolecular proportions in methanolic solution gave at ambient temperature 4-(1-methoxyethyl)phenol with a selectivity of 87%, and a conversion of 89% (ref.55). 

A modified Friedlander synthesis involving a-nitrocarbonyl and 2-aminocarbonyl compounds was reported (50JCS395, 51JCS2992, 53JCS3914,57JA1502). 2-Aryl-3-nitro-l,2-dihydroquinolines 197 was prepared from )S-nitrostyrenes 196 and 2-aminobenzaldehyde 17 using DABCO. Other alkyl nitro olefins were also used. When 2,3-dichloro-5, 6-dicyanoquinone (DDQ) is added to 3-nitro-l,2-dihydroquinolines 197,... 

A soln. of 2,3-dichloro-5,6-dicyanoquinone in abs. dioxane added to a soln. of ethyl l-methyl-2-oxo-l,2,3,4-tetrahydropyrimidine-5-carboxylate in the same solvent, and heated 1 hr. at 90° ethyl l-methyl-2-oxo-l,2-dihydropyrimidine-5-carboxylate. Y 80.2%. F. e. s. A. Takamizawa and K. Hirai, Ghem. Pharm. Bull. 12, 1418 (1964). 

Dichloro-5,6-dicyanoquinone Replacement of hydrogen by hydroxyl 9 -Hydroxy steroids... 

OxidatiV0 Enamine Catalysis. The oxidative transformation of enam-ines derived from saturated aldehydes into a,(3-unsaturated iminium ions by dehydrogenation has been independently disclosed in 2011 by Li, Wang, and co-workers [108] and by Hayashi and co-workers [109]. This chemistry provides an alternative procedure to the standard iminium catalysis, which relies on the use of a,(3-unsaturated aldehydes. Both research groups used diphenylprolynol trimethylsilyl ether as the chiral amine catalyst but while Wang employs o-iodoxybenzoic acid (IBX) as the stoichiometric oxidant [108], Hayashi s procedure relies on the use of 2,3-dichloro-5,6-dicyanoquinone (DDQ) as the oxidant [109]. This oxidation can be performed in the presence of a suitable nucleophile... 

Benzyl nitriles. 2 eqs. 2,3-dichloro-5,6-dicyanoquinone rapidly added to a soln. of 2-( -methoxyphenyl)butane and trimethylsilyl cyanide in methylene chloride, and the mixture stirred at 60° for 24 h - product. Y 68%. F.e. and with simultaneous dehydrogenation/aromatization s. M. Lemaire et al., Chem. Letters 1988, 1581-4. 

Carbon disulfide s. under BuLi Methyl iodide s. under Co iCO) and CoClj 2,3-Dichloro-5,6-dicyanoquinone s. under RLi Iminocarbonyl chlorides s. under Mg Trimethylsilyl chloride s. under Zn Chlorotitanium triisopropoxide s. under BuLi... 

Metallocenes of these metals are exceptionally stable because they achieve lie configuration of the valence shell. They are stable in air in the solid state. They undergo reduction with difficulty by contrast, in acidic media, they are easily oxidized to the [MCP2] cations. Dilute, acidic solutions of Fecp are blue-green, while more concentrated solutions are blood red. Neutral and even more basic solutions of the ferrocenium cation Fecp undergo decomposition to give ferrocene and iron hydroxide. Ferrocene forms charge transfer complexes with nitrobenzene, tetracyanoethylene, and 2, 3-dichloro-5, 6-dicyanoquinone. 

Dichloro-5,6-dicyanoquinone as oxidizing agent Oxidative dimerization of enols and enolizable ketones... 

Methyl allogibberate refluxed with excess 2,3-dichloro-5,6-dicyanoquinone in di-oxane product. Y 97%. F. e. s. B. E. Cross and R. E. Markwell, Chem. Commun. 1972, 442. 

Methyl iodide s, under (CgH )2PLi 2,3-Dichloro-5,6-dicyanoquinone s. under TsOH... 

Perchloric acid/2,3-dichloro-5,6-dicyanoquinone Radical cations... 

Trifluoroacetic acid added to a soln. of the startg. aldehyde amide (prepn. s. 8) in toluene, and the resulting soln. refluxed 4 hrs. under Ng in the presence of a Dean-Stark trap dihydropyridone deriv. (Y 80%), dissolved in benzene, treated with 1.1 equivalents 2,3-dichloro-5,6-dicyanoquinone, and stirred 2.5 hrs. at room temp. pyridone deriv. (Y 96%). A. I. Meyers et al., J. Org. Chem. 38,1974 (1973). 

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