Biocatalysts in organic syntheses : proceedings of an International symposium organized under auspices of the Working Pa...
Biocatalysts in organic syntheses
The Chichibabin amination of diazines geometrical isomerism in anions of aromatic amines
The first part of this thesis describes investigations into the mechanistic aspects of the Chichibabin amination of some diazines in liquid ammonia containing potassium amide.The nucleophilic attack of the amide ion on 4-phenylpyrimidine readily takes place at C-2, due to its low electron density, and at C-6 because of the thermodynamic stability o...
Synthesis and amination of naphthyridines
In the introduction of this thesis (chapter 1) the reactions of nephthyridines with potassium amide which were known at the start of our research are reviewed. It is shown in chapter 2, that in the amination of 1,X-naphthyridines with potassium amide in liquid ammonia at about -35° to -45°C the initial adduct formation is charge controlled. Thus, a...
The reactivity of substituted purines in strongly basic medium : the occurrence of geometrical isomerism in the anions o...
In this thesis two subjects are described: a. the amination of substituted purines by potassium amide in liquid ammonia and b. the occurrence of geometri cal isomerism in the anions of aromatic amino compounds.It is shown that the first step in the amination of purines, being present as anions under these strongly basic conditions, is the formation...
Homoaromatics as intermediates in the substitution reactions of 1,2,4,5-tetrazines with ammonia and hydrazine
This thesis describes some nucleophilic substitution reactions between the red 1,2,4,5-tetrazines and hydrazine-hydrate or ammonia. Special attention was paid to the occurrence of the S N (ANRORC) mechanism in these substitution reactions. This mechanism comprises a sequence of reactions, involving the A ddition of a N ucleophile to a heteroaromati...
Thermal and photochemical reactions of dihydrodiazines
This thesis describes the results of an investigation into the thermal and photochemical reactivity of dihydrodiazines.In order to prepare the title compounds the diazines and some phenyldiazines are treated with phenyllithium in ether, yielding adducts resulting from attack of phenyllithium on the various positions of the heteroaromatic ring. With...
[Sigma]-Adducts of pteridines and 3-deazapteridines, structure and reactivity
In the introduction of this thesis the reactions of pteridines and pyrido[2,3- b ]-pyrazines with nucleophiles are reviewed. In the following chapters the results of an NMR investigation on the formation of σ-adducts between these azaaromatic ring systems and nitrogen nucleophiles, especially KNH 2 /NH 3 , are described. In order to establish the s...
Ring transformations in reactions of pyrimidine and N-alkylpyrimidinium salts with nucleophile
Paper IOn treatment with liquid ammonia at -33°C, the quaternary pyrimidinium salts, i.e. 1-methylpyrimidinium methyl sulfate, 1,2-dimethylpyrimidinium iodide, 1,4,6-trimethyl-pyrimidinium iodide and 1,2,4,6-tetramethylpyrimidinium iodide demethylate yielding pyrimidine. 2-methyl-, 4,6-dimethyl- and 2,4.6-trimethylpyrimidine, respectively. It was o...
Reactions of pyridazines and pyridazine 1-oxides with nitrogen-containing nucleophiles
In dit proefschrift is een orienterend onderzoek beschreven naar het chemisch gedrag van halogeen-pyridazinen en halogeen-pyridazine-N-oxiden met kaliumamide in vloeibare ammoniak, met methanolische ammoniak en met vloeibare ammoniak. Dit onderzoek hangt nauw samen met uitvoerige studies over de reactiviteit van pyridinen, pyrimidinen en pyrazinen,...
