Alexander R. Forrester

NOVEL HETEROCYCLIC DYES AS DNA MARKERS. PART I. SYNTHESIS AND CHARACTERIZATION

Abstract A range of new cyanine dyes has been prepared and characterised. These dyes are more conveniently synthesised by the reaction of two heterocyclic quaternary salts. The dyes contain a purine heterocycle coupled to an aro-(thia-, selena-, oxa-, imida)zole and are in the form of iodide or p -toluenesulphonate salts. Characterisation were done by FABMS and NMR spectroscopy. These dyes can be used as fluorescent dyes for DNA marking in the diagnosis of malaria parasites.

Iminyls. Part 3. Formation of triaryl-pyridines and -pyrimidines from aryl-β-arylvinyliminyls

Aryl-β-arylvinyliminyls, produced by oxidation of the corresponding imino-oxyacetic acids with persulphate or by thermolysis of the t-butyl peresters of these acids, abstract hydrogen giving imines which dimerise and/or are hydrolysed to ketones. The bicyclic dimers so formed readily undergo oxidative fragmentation to triaryl-pyridines and/or -pyrimidines.

Iminyls. Part 7. Intramolecular hydrogen abstraction; synthesis of heterocyclic analogues of α-tetralone

A series of alkyl (C4 or greater) heteroaryl iminyls have been generated by oxidation of the corresponding oxime-O-acetic acids with persulphate. These react to give fused heteroaryl cyclohexanones.

Novel heterocyclic dyes as DNA markers. Part II. Structure and biological activity

Abstract Management and control of malaria allows epidemiological studies. Microscopic examination of blood films is actually the most rapid and accurately method for diagnosis malaria. Malaria parasites can be stained with many dyes, while Romanowsky-type stains are usually used for morphological studies, fluorescent cyanine dyes are used for rapid diagnosis and quantification. Quantum mechanical methods were used for structural characterisation. The results have allowed the structure activity correlations to be established.

Structural study of 3-oxypropyltin compounds

The structures of (3-hydroxypropyl)iododiphenyltin 3 and 2,7-diiodo-2,7-diphenyl-1,6-dioxa-2,7-distannacyclodecane 6 have been determined by single-crystal X-ray diffraction. Compound 6, obtained by controlled thermolysis of 3, has a tricyclic structure, with a central Sn2O2 ring arising from transannular, Sn–O [i.e. Sn(2)–O(6) and Sn(7)–O(1)] interactions. The terminal rings in centrosymmetric 6 are in a transoid arrangement with respect to the central Sn2O2 ring, i.e. there is a stepped geometry. The tin atoms have trigonal-bipyramidal geometries being bonded in equatorial sites to two carbons and one oxygen [Sn–O′,i.e. Sn(2)–O(1) 2.060(7)A] and in axial sites to iodine [Sn–I 2.776(1)A] and to oxygen [Sn–O, i.e. Sn(2)–O(6) 2.268(7)A]: I–Sn–O 161.7(2)°. In C6H6 and in chlorocarbon solutions, 6 exists as a 4.2 : 1 mixture of two isomers: the major one has the solid-state structure while the minor one has the terminal rings in an umbrella configuration, i.e. the terminal rings are cisoid with respect to the central Sn2O2 ring. Two sets of tin couplings to C(3)[Cβ] and to C(4)[Cα] of each isomer were observed. Compound 3 exists as a chelate complex, with trigonal-bipyramidal tin: three equatorial C, with I[Sn–I 2.857(1)A] and O[Sn–O 2.487(8)A] axial [I–Sn–O 168.3(2)°]. Chelation persists in chlorocarbon solvents.

Iminyls. Part 2. Intramolecular aromatic substitution by iminyls. A new route to phenanthridines and quinolines

Biphenyl-2-yl- and triarylvinyl-iminyls, generated by oxidation of the corresponding imino-oxyacetic acids with persulphate and by thermolysis of the t-butyl peresters of these acids, readily cyclise in high yield to phenanthridines and quinolines, respectively.

Predicting the macromolecular structure and properties of lignin and comparison with synthetically produced polymers.

Summary Determining the structure of the plant polymer lignin is not feasible because of the heterogeneous structure of this polymer and the difficulties encountered in its extraction. Therefore, computational chemistry can provide information, which may otherwise be unavailable. Based on experimental results, computational chemistry was used to mimic the processes involved in lignin formation. Synthetic polymers also were prepared from the three major lignin precursors and their physical properties were shown to give good correlation with computational models constructed to represent these polymers. Both computational and experimental results, demonstrated that the higher the degree of methoxylation, the more flexible the polymer and this was shown to be dependent on the type of inter-unit linkage. Using the same experimentally derived parameters, a model was constructed to represent a generalised lignin. This model was shown to be a flexible, closely packed structure and this was attributed to the predominance of 8-O-4 linkages, which allowed closer stacking of the aromatic rings.

Reactions of ozonate and superoxide radical anions

Potassium ozonate has been prepared by reaction of ozone with potassium superoxide dispersed in Freon-12. Orange solutions of potassium ozonate in benzene or toluene containing 18-crown-6 react with nitrone traps to give spin adducts mainly derived from the oxide radical anion, which is a decomposition product of the ozonate radical anion. With 2-methyl-2-nitrosopropane in toluene solution the ozonate gives five nitroxide radicals in whose formation the oxide radical anion is again implicated. With nitrosobenzene electron transfer occurs. Comparable reactions with superoxide are described.

Iminyls. Part 9. Intramolecular addition of an iminyl to an alkene

Phenyl o-styrylphenyl iminyl, generated by oxidation of the corresponding O-carboxymethyloxime with persulphate and by thermolysis of the perester of that acid, cyclises to give a mixture of isoquinoline and 1H-isoindole derivatives. The intermediate radicals have been investigated by e.s.r.

Iminyls. Part 1. Generation of iminyls

Four methods for producing iminyl radicals are described: oxidation of imino-oxyacetic acids with persulphate, thermolysis of the corresponding peresters, oxidation of oxime ethers with di-t-butyl peroxide, and photolysis of oxime oxalates. The first two are the most useful for chemical studies.