Perimidine 1.2- disubstituted

Pseudo-bases derived from 2-unsubstituted 1,3-dialkylperimidinium salts disproportionate into 1,3-dialkylperimidones and l,3-dialkyl-2,3-dihydroperimidines, the former always predominate. By contrast, l-aroyl-3-alkylperimidinium salts (203), formed in situ from l-/ -perimidines and aroyl chlorides, produce pseudobases (204) which exist exclusively in the acyclic form (205). Interestingly, heating with alkali cleanly converted (205) into the corresponding 1,2-disubstituted perimidines (206). This reaction is of preparative significance for the introduction of aryl and heteroaryl groups in position 2 of perimidines (81RCR1559). 

Disubstituted perimidines could not be quaternized by methyl iodide even on prolonged heating. Alkylation of 6(7)-monosubstituted perimidines gives a mixture of the 1,6- and 1,7-isomers <81RCR816>. 4(9)- or 6(7)-Nitroperimidine is difficult to A-alkylate. The anion of 2-trifluoro-methylperimidine has resisted methylation. C-Alkylation in the nucleophilic 4(9)-position may be a... 

In the past year, reviews on 1,8-naphthyridines, perimidines, polyazaphen-anthrenes, 3-azabicyclo[3.3.1]nonanes, and 1,2- and 2,1-benzothiazines have appeared. Reviews on specialist aspects of pyridine chemistry are devoted to the reactions of newly available pyridines, a,a -disubstituted pyridines, the reactions of pyridines with nucleophiles, the electrochemistry of IjT-disubstituted 4,4 -bipyridinium ions (the viologens such as paraquat), dihydropyridines, and 4-aryl-dihydropyridines (a new class of calcium antagonists). Reviews have been published on the cyclization of oximes and amides to quinolines and isoquinolines, quinoline- and isoquinoline-diones, benzo[fl ]- and benzo[c]-quinolizinium ions, azachrysene preparation, quinazolines with plant-growth-regulating and biocidal activities, quinazolines in pharmaceutical research, isotopic hydrogen exchange in... 

---