Newly prepared azo compounds and several commercially available indicators were investigated for their applicability as colored isoelectric point (pI) markers for isoelectric focusing (IEF) in the acidic range below pH 5. The majority of compounds described here can serve as primary standards since their pI values were determined by UV-VIS spectrophotometry independently IEF and direct measurement with a pH electrode. Subjected to gel IEF they show narrow and well-observable zones of different colors. Finally, our work resulted in suggestion of a color ladder composed of pI markers covering the pH range from 1.5 to 4.7.
Reaction of a series of N-alkyl- and N,N-dialkylbromoacetamides 1a-1e with phenanthridine afforded quaternary phenanthridinium salts 2a-2e. These compounds treated with triethylamine form azomethine ylides which undergo a cycloaddition reaction with activated C=C bond, giving 3-(N-alkylcarbamoyl)-1,2,3,12b-tetrahydropyrrolo[1,2-f]phenanthridines 3a-3e, 4c, 5c, 6c or 3-(N-alkylcarbamoyl)-2,3-dihydropyrrolo[1,2-f]phenanthridine 7c. Their stereochemistry was studied by NMR spectroscopy. The best results were obtained with fumaronitrile as a dipolarophile. It has been found that the ylides react in syn conformations but if 1-adamantyl moiety is bound to the ylide, it reacts in anti conformation, too. The azomethine ylides show a very poor reactivity towards dimethyl fumarate or dimethyl maleate. Yet we could prepare products for ylide bearing 1-adamantyl group.
A series of N-acylated N-substituted sulfonamides was prepared for the first time in good yields and with excellent conversion by the reaction of N-substituted-N-(p-toluene) sulfonamides (1) with acetyl chloride and bromoacetyl bromide (2), respectively, in the presence of a catalytic amount of anhydrous ZnCl 2 .
Upon treatment with base N-substituted carbamoylmethylphenanthridinium salts were converted into azomethine ylides. These intermediates were intercepted with symmetrically substituted dipolarophiles, and the stereochemistry of the cycloadducts has been found to be dependent on the substitution at the amide nitrogen atom.
The reactions of ethyl N-alkylaminoacetates 1 in the presence of formaldehyde and dipolarophiles fumaronitrile and dimethylfumarate 3 were investigated. They were followed and the results compared of reactions under classical heating and heating by MW either in solvent or without solvent or with solid supports. It has been found out that application of specific reaction conditions for the preparation of desired trisubstituted pyrrolidines 4a-4c and 5a-5c is dependent on the nature of the dipolarophile used. In the case of fumaronitrile the direct solventless reaction under microwave irradiation seems to be the most convenient method; in the case of dimethyl fumarate mineral support (predominantly basic activated Al 2 O 3 ) must be employed. In the absence of olefinic dipolarophile double bond C=O in a formaldehyde molecule serves as dipolarophile 9 to form 1,3-oxazolidines 6a-6c. These are also by-products when toluene is used as a solvent. 1 Yet in the case of addition of basic Al 2 O 3 we do not observe oxazolidine formationand GC-MS analysis shows just a complex set of peaks.
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