Acridizinium salts, synthesis

Acridizinium salts, lO-(phenylsuIfonyl)-synthesis, 2, 545 5-Acridone UV spectrum, 2, 156 9-Acridone acylation, 2, 352 alkylation, 2, 350 synthesis, 2, 422 Acridone alkaloids, 2, 513 9-Acridonequinones synthesis, 2, 348 Acridones fluorescence, 2, 20 mass spectrometry, 2, 134 synthesis, 2, 93, 401 from 3-arylanthranils, 2, 496 from benzotriazinones, 2, 506 tautomerism, 2, 347 Acridones, tetrahydro-synthesis... 

Uses. Tetramethylene sulfone has high solvent power for aromatics and has been used extensively by Olah and co-workers for Friedel-Crafts type nitrations and for studies of the mechanism of nitronium tetrafluoroborate nitration of alkyl-benzenes and halobenzenes in homogeneous solution. It is a superior solvent for quaternization of tertiary amines with alkyl halides, since it has a high dielectric constant and does not enter into side reactions observed with nitrobenzene and dimethylformamide. For example in the synthesis of the acridizinium salt (3), Bradsher and Parham effected quaternization of (1) with benzyl bromide in tetramethylene sulfone at room temperature in excellent yield. Several other salts analagous to (2) were obtained in good yield and in crystalline form with use of tetramethylene sulfone, whereas with other solvents the products were colored... 

The first synthesis of the benzo[6]quinolizinium ion (Scheme 98, Table 9, example 1) was by hydrobromic acid-catalyzed cyclization of the quaternary salt formed between 2-pyridinecarbaldehyde and benzyl bromide. Aromatic cyclodehydration has continued to the present as almost the only method used for the preparation of the acridizinium ion, its derivatives and benzo analogs. Because of its instability, 2-pyridinecarboxaldehyde has been replaced by more efficient derivatives. The first of these was the oxime (example 2) which not only gave a better overall yield, but also made possible the isolation of a crystalline intermediate (181 Z = NOH). The disadvantages are that it is not suitable for high temperature cyclizations involving polyphosphoric acid, and some products (182) (e.g. example 10, Table 10) may tend to form double salts with hydroxylamine hydrobromide. 

Table 9 Synthesis of Acridizinium Derivatives by Cyclodehydration of Quaternary Salts (Scheme 98)...

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