Acridizinium salts

Acridizinium salts, 8-diazo-7-oxo-in lithography, 2, 570 Acridizinium salts, 7,10-dihydroxy-oxidation, 2, 539... 

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... 

A number of cycloadducts have been prepared from substituted acridizinium salts. Bradsher and Stone studied the rate of addition of st30-ene to acridizinium salts having methyl groups at the meso (6,11) positions. 

The aromatic cyclodehydration (46CRV(38)477> of suitable quaternary salts bearing carbonyl groups has provided convenient access to both benzo[a]- and benzo[6]-quinoIizinium (acridizinium) salts and their benzo analogs, each of the two systems requiring a different approach. The two approaches can be classified according to their synthetic purpose as type A or type B. 

Fig. 2.5.2. Spectrophotometric titration of acridizinium salt 5a with ct DNA in phosphate buffer (10 mM, pH 7.0) thin arrows indicate the increasing or decreasing absorption bands during the course of the titration thick arrows indicate isosbestic points.

Thus aqueous solutions of the achiral acridizinium salts 5a and 5b alone have no CD activity, but an ICD is observed on addition of DNA to these salts the spectra differ in phase and intensity, however (Figure 2.5.4). The shapes of the CD signals roughly resemble the broadened long-wavelength absorption spectrum of the corresponding acridizinium salts. The positive ICD of 5b (Figure 2.5.4B, spectrum 2)... 

Fig. 2.5.6. Linear-flow-dichroism (A), and reduced linear-flow-dichroism (B) spectra of acridizinium salt 5a in buffer solution (1 mM EDTA, 10 mM Tris buffer, 10 mM NaCI, pH 7.0) solid line, DNA without dye dashed line, [5c]/[DNA] = 0.025.

Wang and Jones have investigated the solid-state reactivity of the series of acridizinium salts shown in Scheme 21 [116]. Many of these undergo single crystal-to-single crystal dimerization when irradiated and can thus be monitored by x-ray... 

The preparation and properties of the charge transfer salt between azonia derivative (2 and 246) and tetracyanoquinodimethane (TCNQ) were reported (88MI2). Wang and Jones reported that acridizinium salt underwent single crystal — single crystal photodimerization (87T1273). 

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... 

Acridizinium salts also undergo [4+4] dimerization to yield (287) and aspects of the intramolecular interaction and reaction of the arene chromophores in compounds of type (288) with n=l-6 and 8 have been publishedf The quantum yields of the reversible intramolecular dimerization have been determined in several solvents and are reported to depend upon the value of n. Formation of the dimer arises from the intramolecular excimer and a common pericyclic transition state is assumed for the forward and back reactions. 

The [4+ + 2] cycloadditions proceed in a regiospecific manner with the nucleophilic carbon of the electron-rich dienophile attaching to the expected electrophilic site of the aromatic quaternary salt (e.g., C-6 for acridizinium salts, C-l for isoquinolinium salts) and the rate of reaction (ketene aminals, ketene acetals, enamines > cyclopentadiene > 2,3-di-methylbutadiene > styrene > dihydropyran > 2-butene > maleic anhydride) does increase as the nucleophilic character of the dienophile is enhanced [Eq. (66)].l48e 149... 

Aromatic cyclodehydration has been used in the preparation of several indolo[2,3-a]acridizinium salts (43) (Chart V). Reaction of l-formyl-)3-carboline (LXIX) with benzyl bromides in dimethyl formamide at room temperature provided the quaternary salts (LXX R = H or OMe) which were smoothly converted to the desired indolo-[2,3-a]acridizinium salts (LXXI) by action of polyphosphoric or concentrated hydrochloric acid (when R = OMe). 

The mechanism for forming acridizinium salt is similar to the Bradsher Cyclization when a carbonyl group exists in the reaction system. However, the mechanism for forming oxazole[3,2-a] pyridinium is different from what is proposed here. 

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