2.3- Dichloro-4,5 -dicyanobenzoquinone

Cyanoamidines such as (10) are converted into the more useful 2-formyl-A-norsteroids (11) by reduction with lithium in methylamine (buffered with ammonium acetate) followed by hydrolysis on hydrated alumina. This yields a mixture containing approximately 5 parts of the 2j5-aldehyde and 3 parts of the 2a-aldehyde (11). Both aldehydes are smoothly dehydrogenated by 2,3-dichloro-5,6-dicyanobenzoquinone in the presence of acid to the 2-formyl--A-iiorsteroids (12). ... 

A two-step transformation of conjugated dienes into non-conjugated ones was proposed for the synthesis of the difficult to-obtain lapachol (355) (a member of a class of antimalarial agents having an activity against the Walker carcinosarcoma 256) from the more available isolapachol 352183. This method consists in an oxidative cyclization of isolapachol 352 by 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) to form a mixture of the products 353 and 354 (equation 127). Treatment of this mixture with dilute acid in... 

This estimation has been made for a reaction between the anion-radical of tetracyanoquinodi-methide (TCNQ) and 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ lida and Akamatu 1967) (TCNQ) + DDQ = TCNQ + (DDQ). The equilibrium constant of the reaction was determined spectrometrically in AN. Having K and y2(DCNQ) as the known values, y2(TCNQ) was determined to be 38 mV. The experimental (polarographic) value was 40 mV. As seen, the calculated and experimental values turned out to be close. 

An example of the 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) dehydrogenation is that of converting tricyclic 236a to conjugated substance 236b (87TL4929). 

The kinetic instability of the polyhydrofullerenes is shown by the reaction with 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) in refluxing toluene. Thereby, the Birch-Hiickel products completely convert into Cjq, which shows that the hydrogenation is completely reversible (Scheme 5.2) [42]. 

The Jones reagent851 and < rt-BuOOH in the presence of chromium(VI) complexes852,853 were found to be particularly useful in the oxidation of tetralins and indans. Oxidation with 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) occurs with an exceptional mechanism.854 In contrast with the radical processes observed in other oxidations DDQ generates a carbocation by hydride abstraction that is trapped by water to form an alcohol ... 

A more direct way to attain the dehydrogenation is to allow a chromane to react with a high-potential quinone, such as chloranil or 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ138) [Eq. (12)]. The reaction, usually carried on in benzene or dioxan, with yields in the... 

Catalytic hydrogenation of porphyrazines or their Mg complexes with palladium black gives tetrahydrogenated compounds which are oxidized back to the starting materials by a stoichiometric amount of 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ).2 The royal blue products are degraded to cw-succinimide and maleimide, and considered to be the tetraaza analogues of either bacterio-chlorins or isobacteriochlorins. Photochemical reduction of monoazaporphyrins is reported to occur at the meso positions. 

Catalytic hydrogenation of the diene (96), from mercuric acetate oxidation of betulin diacetate, yielded (97) and (98). The latter was further reduced to the 18/3H,19/8-lupane (99).70 Isomerization of betulin diacetate with hydrobromic acid in acetic acid-acetic anhydride afforded (97), instead of the usual products with ring E enlarged.71 Glochidone (100) is readily prepared from lupen-3-one by oxidation with 2,3-dichloro-5,6-dicyanobenzoquinone.72 73... 

Since hot pepper is important for the food and the pharmaceutical industries, a range of different methods have been developed for the analysis of capsaicinoids in plant material and finished products. The separation of CPS (la) and nonivamide (11) is especially challenging, since these compounds have similar behavior in many chromatographic conditions. Since synthetic nonivamide is the most common adulterant of capsicum oleoresin, various strategies have been suggested to overcome this problem. Capillary GC does not require previous derivatization of capsaicinoids, but its separatory power seems lower than that of HPLC, currently the most popular technique for the quantization of capsaicinoids. GC is, however, the method of choice for the analysis of the acyl moieties of capsaicinoids as methyl esters. These can be directly produced from capsaicinoids by oxidative N-dealkylation with DDQ (2,3-dichloro-5,6-dicyanobenzoquinone), followed by alcoholysis of the resulting amides with methanol in the presence of an acidic resin (Scheme 4.4) [41]. 

ALLYLIC OXIDATION f-Butyl hydroperox-ide-Chromium carbonyl. 2,3-Dichloro-5,6-dicyanobenzoquinone. 

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