Oxidative transformations of heterocyclic

Iminium salts, oxidative transformation of heterocyclic, 41, 275 Indole Grignard reagents, 10, 43 Indole(s)... 

Imidazoles, 35, 375 4f/-Imidazoles, 35, 413 Imidazolium azolate inner salts, 60, 197 At-lmines, heteroaromatic, 17, 213 29, 71 Iminium salts, oxidative transformation of heterocyclic, 41, 275 Indole Grignard reagents, 10, 43 Indole(s)... 

Desulfonation reaction (reductive and oxidative desulfonation, nucleophilic substitution, elimination, and SO2 extrusion) in synthesis and transformations of heterocycles 99T10547. 

Ring opening of epoxides and some other transformations of heterocycles on aluminum oxide 97T7999. 

A group of Italian workers from Modena, led by Professor Taddei, has reviewed published work on the conformations of acyl groups in heterocyclic compounds, including both C-acyl and N-acyl derivatives. The first recent review of the basicity and acidity of azoles, covering both gas-phase and solution measurements, is presented by a group of Spanish workers (Catalan et al.). H. Weber has summarized the considerable recent progress in oxidative transformations of heteroaromatic iminium salts. 

This section deals with transformations of heterocyclic rings and includes not only addition of carbenes and nitrenes, but also rearrangements frequently following these additions. Also included are topics such as the synthesis of Reissert compounds as well as miscellaneous oxidations and reductions. 

Among the transformations of heterocycles, the rearrangement oxepines (381)—benzene oxides (382) phenols (383) is best known (equation 181). This rearrangement was described in detail in several surveys 334-336 -pijg most studied aspect of the arene oxide chemistry is the ring expansion to oxepines, on the one hand, and aromatization reaction to phenols, on the other. 

N-Oxides of heteroaromatics, reactions with ketenes 79H(12)819. Photochemical electron transfer in reactions of N-heterocycles 82YZ716. Photochemical transformations of heterocyclic enamides 78S489. Photochemistry of N-heterocycles 82AHC(30)239. 

Gallos JK, Lianis PS, Nicolaides DN (1989) Reactions of furazano[3,4-h]quinoxalines with phosphorus yUdes and an unusual oxidative transformation of the transyUdation product. J Heterocycl Chem 26 1415-1420... 

Transformations of nitro compounds, nitrones, nitrates, hydroxylamines, and amino-A-oxides into heterocycles 98SL939. 

Dibenzo[/),/]thiepin-10(l 1H)-one (1) is an important synthon for the transformation of thiepins into other heterocycles. Oxidation with selenium(IV) oxide gives dibenzo[7>,/]thiepin-10,l 1-dionc (2), in 45% yield,38 which can be condensed with a series of benzaldchydes in the presence of ammonium acetate to provide the substituted 2-aryldibenzo[2,3 6,7]thiepino[4,5-t/]imidazoles 3, known to have anti-inflammatory properties.38... 

The synthesis of novel heterocycle-fused furo[3,4-d]isoxazoles via ring transformation of 2-isoxazoline-2-oxides by Lewis acids was reported <96H(42)289>. A practical application of the... 

Monoalkylation of Af-tosylallylamine 10 with dibromoalkane 101 proceeded in 60-90% yield (Eq. 10 see also Scheme 3 and Eq. 2) [17]. The bromoalkyl-amines 102 were converted to nitro compounds 103. In situ transformation of 103 into nitrile oxides led to spontaneous cycloaddition with formation of isox-azolines fused to 5-, 6-, and 7-membered ring heterocycles 104 a-c. Under very high dilution conditions, 103 d was converted to 104 d, an isoxazoline fused to an 8-membered azocine, in low (10%) yield. 

The transformation of sulfonylureas by Streptomyces griseolus grown in a complex medium containing glucose when the methyl group of the heterocyclic moieties is hydroxylated, and for some substrates, subsequently oxidized to the carboxylic acid (Romesser and O Keefe 1986 O Keefe et al. 1988). 

The generation of other heteroq cles from Bfx and Fx has been the subject of exhaustive investigation. The most important transformation of Bfx to other heterocycles has been described by Haddadin and Issidorides, and is known as the Beirut reaction . This reaction involves a condensation between adequate substituted Bfx and alkene-type substructure synthons, particularly enamine and enolate nucleophiles. The Beirut reaction has been employed to prepare quinoxaline 1,4-dioxides [41], phenazine 5,10-dioxides (see Chap. Quinoxahne 1,4-dioxide and Phenazine 5,10-dioxide. Chemistry and Biology ), 1-hydroxybenzimidazole 3-oxides or benzimidazole 1,3-dioxides, when nitroalkanes have been used as enolate-producer reagent [42], and benzo[e] [ 1,2,4]triazine 1,4-dioxides when Bfx reacts with sodium cyan-amide [43-46] (Fig. 4). 

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