Search

1-Methyl-3-methylene-2,4(1H,3H)-quinolinedione (2), prepared from 4-hydroxy-1,3-dimethyl-2(1H)-quinolinone (1) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) gives the dimer 3. Compounds 2 also reacts in situ with 2,2-dimethyl-2H-1-benzopyran and with isopropenyl acetate to give Diels-Alder cycloadditions products

1-Methyl-3-methylene-2,4(1H,3H)-quinolinedione (2), prepared from 4-hydroxy-1,3-dimethyl-2(1H)-quinolinone (1) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) gives the dimer 3. Compounds 2 also reacts in situ with 2,2-dimethyl-2H-1-benzopyran and with isopropenyl acetate to give Diels-Alder cycloadditions products

Reaction of 2,2′-di(hydroxyamino)diaryl sulphones with sodium hydroxide in aqueous dioxan at 20° yields dibenzo [b,f][1,4,5]thiadiazepine 5,11,11-trioxides (X), phenazine 5-oxides (XIV), and phenazine 5,10-dioxides (XV). The formation of the phenazine derivatives probably involves disproportionation of the aryl hydroxylamines, followed by Smiles rearrangement, and then loss of the sulphino-group. In the presence of zinc, the arylhydroxylamines are converted into phenazines (IV) and thiadiazepine 11,11-dioxides (VII). The mechanism of the alkaline reduction of 2,2′-dinitrodiaryl sulphones1 is discussed in the light of these results. Some of this work has been reported.2Treatment of 2-(hydroxyamino)aryl phenyl sulphones with sodium hydroxide at 20° results in loss of the phenylsulphonyl group. For example, 6-chloro-2-(hydroxyamino)diphenyl sulphone affords sodium benzenesulphinate and 3,3′-dichloroazoxybenzene. Cleavage of a C–S bond does not occur in 4-(hydroxyamino)diphenyl sulphone. Possible mechanisms for the reaction are discussed.

Treatment of 2-(hydroxyamino)aryl phenyl sulphones or bis-(2-hydroxyaminoaryl) sulphones with aqueous sodium hydroxide at 20° gives 2-hydroxy-2′-(arylsulphonyl)azoxybenzenes (V) and (VII) and arenesulphonate anions. The hydroxy-group in the azoxy-product is derived from the sulphone or hydroxyamino-groups and not from the added base. 2-Nitrosoaryl phenyl sulphones, 2,2′-bis(arylsulphonyl)azoxybenzenes, and 2-nitrosophenols are shown not to be intermediates.

Reduction of 2,2′-dinitrodiaryl sulphides, sulphoxides, and sulphones with zinc and sodium hydroxide in aqueous dioxan afforded phenazines (V), dibenzo[b,f][1,4,5]thiadiazepines (IV; X = S or SO2), dibenzo[b,f][1,4,5]-thiadiazepine N-oxides, and other products. Phenazines arise by intramolecular nucleophilic rearrangement of a partially reduced species, followed by loss of the sulphur-containing group. Studies of the reduction of 2-amino-2′-nitrodiphenyl sulphone and of dibenzothiadiazepine derivatives show that these compounds are not intermediates in the formation of phenazines.