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Type PA4 Production Methods

The stmcture and the mechanism of formation of the pyrroloquinoxaline 190 in this reaction were partly clarified by realizing closure of the ring in compound 187 in an atmosphere of argon in the absence of carbon monoxide. Moreover, it was shown that heating of compound 187 in an atmosphere of argon in the absence of the palladium catalyst also leads to a small yield of the pyrrolo[l,2-a]quinoxalines. The part played by the catalyst in the closure of the pyrazine ring is not understood. [Pg.166]

The heterocyclic quinone 192 can be used in the synthesis of more complex condensed systems by the Diels-Alder reaction with various dienes (Al-Sammerrai et al. 1980). [Pg.167]

In spite of the fact that l-(2-aminophenyl)pyrrole is considered as an excellent reagent in the synthesis of 4-substituted 4,5-dihydropyrrolo[l,2-a]quinoxalines, the [Pg.167]

Cyclization in a basic medium also takes place in the case of the reaction of benzaldehyde with derivative of l-(2-aminophenyl)pyrrole. For example, treatment of the aminoester 164g with an equimolar amount of benzaldehyde in pyridine gives 4,5-dihydropyrrolo[l,2-a]quinoxaline 200 and not the expected pyrroloben-zotriazocine 199 (Korakas et al. 1996). The postulated intermediate in this reaction is probably the imine 198. The reaction of compound 164a with benzaldehyde in [Pg.168]

The synthesis of 3-(4-alkyl-4,5-dihydropyrrolo[l,2-a]quinoxalin-4-yl)-2/f-chromen-2-one derivatives by a three-component reaction of salicylaldehyde, p-keto esters, and l-(2-aminophenyl)pyrrole using piperidine-iodine as a dual system catalyst is reported (Table 3.2) (Alizadeh et al. 2014) [Pg.170]


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