2, 3-Dichloro-5, 6-dicyano- 1, 4-benzoquinone

Cl2, ammonium nitrate on Clayfen, Oxone on wet alumina, silver nitrate and iodine,2,3-dichloro-5,6-dicyano -1,4-benzoquinone (DDQ) in acetonitrile... 

Isopropenylbenzofuran (124, Scheme 30) affords good yields of the adducts 123 and 125 on separate reaction with maleic anhydride and tetracyanoethylene. With but-3-en-2-one, 2-isopropenylbenzofuran (124, Scheme 31) affords the adducts 126 and 127 in a combined yield of 29%. When the crude product was dehydrogenated with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone in boiling benzene, the aromatized product 128 (6%) was obtained. It was accompanied by the dicyanodibenzofuran 129, which was found to arise from the excess diene present in the reaction mixture. A speculative mechanism is shown. 

The oxidation of silyl enol ethers184 (105) to enone (107) by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (106) is illustrated in Scheme 42. The electron donor-acceptor complex (red, Xmax = 520 nm) precedes the formation of the adduct 109, which is unreactive, and 108, which is the intermediate of the reaction. At 22 °C, the reaction mixture affords a mixture of 108 and of 109. At 100 °C, 108 is transformed into the final enone 107. 

Cycloadditions of alkenes and alkynes onto imine cation radicals have been reported, with the cation radicals generated by either PIET mediated by DDQ (2,3-dichloro-5,6-dicyano-1,4-benzoquinone)180, or by TIET mediated by FeCb1066. The reaction is shown in Scheme 77. 

AMINO GROUPS 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone. 4-Methoxy-2,3,6-trimethyIbenzenesulfonyl chloride,... 

Treatment of aminoazines, in particular, 6-aminouracil 305, with cyclic oc,(3-unsaturated ketones was described in [235]. The authors showed that 1,3-dimethyl-6-aminouracil reacts easily with cyclooct-2-enone 313, cyclonon-2-enone 316 and other cyclic unsaturated carbonyls (cyclododec-2-enone, cycloundec-2-enon, etc.), forming the appropriate tricyclic compounds 314, 317 or analogues (Scheme 3.86). The interaction of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) with compound 314 leads to a rearrangement of the carbon skeleton and formation of another tricyclic structure 315, while in the... 

Oximes are good precursors to reductive cyclization. A reductive base-induced cyclization of O-aryl oxime 4 will yield the tetrahydroquinoline <1998CL437>. The reduction prevented the normal dihydro-cyclization product from disproportionating to the quinoline and tetrahydroquinoline <1998BCJ2945>. By adding 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) after cyclization, the quinoline is the sole product (Scheme 9). 

PMB ethers can be cleaved oxidatively with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ)11 in dichloromethane/water tor with cerium ammonium nitrate (CAN) in acetonitrile/water.12 Many other protecting groups such as esters, isopropylidene acetals, benzyl ethers, allyl ethers and f-butyldiphenyl silyl (TBDMS) ethers are stable to these conditions (Scheme 2.4). The cleavage reaction, with DDQ is initiated with a single-... 

Scheme 2.5 Mechanism of cleavage of />-methoxybenzyl ethers with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone. Note SET=single-electron transfer.

CBZ COD Cp Cy DABCO dba DBE DBN DBU DCC DCE DDQ DEA DEAD Dibal-H Diphos-4 DMAP DME 0 II Carbobenzoxy = —COCH2Ph 1,5-Cyclooctadienyl Cyclopentadienyl Cyclohexyl 1.4- Diazabicyclo[2.2.2]octane Dibenzylidene acetone 1.2- Dibromoethane = BrCH2CH2Br 1,8-Diazabicyclo[5.4.0]undec-7-ene 1.5- Diazabicyclo[4.3.0]non-5-ene 1.3- Dicyclohexylcarbodiimide = C6H,3—N=C=N—C6H13 1.2- Dichloroethane = CICH2CH2CI 2.3- Dichloro-5,6-dicyano-1,4-benzoquinone Diethylamine = HN(CH2CH3)2 Diethylazodicarboxylate Diisobutylaluminum hydride 1.4- b s-(Diphenylphosphino)butane 4-Dimethylaminopyridine Dimethoxyethane 0... 

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