Reaction of ketenes with N,N-disubstituted 2-aminomethylenecycloalkanones. V. Synthesis of N,N-disubstituted 4′-aminospiro [1,3-dithiane-2,3′-(5′,6′-polymethylene-3′,4′-dihydro-α-pyrones)]

The reaction of 2-carbonyl-1,3-dithiane, a sulfene prepared in situ from 2-chloroearbonyl-1,3-dithiane and triethylamine, with N,N-disubstituted 2-aminomethylvnecycloalkanones gave the 1,4-cycloadducts, namely N,N-disubstituted 4′-aminospiro[1,3-dithiane-2,3′-(5′,6′-poly-methylene-3′,4′-dihydro-α-pyrones)].     

Neopentylallylsodium

Neopentylallylsodium (NpANa) has been prepared by the reaction of neopentylallyllithium with an equivalent amount of sodium 2,2-dimethyl-1-butoxide in hydrocarbon solvent. NpANa is stable in diethyl ether and THF solvents for extended periods of time, and proton NMR and UV data are reported for NpANa in THF at various temperatures. A more substantial degree of ionic delocalization is indicated for NpANa as compared to NpALi and apparently is greater for the trans isomer of NpANa. UV absorption maxima for NpANa and NpALi are explained in terms of cis/trans ratios rather than in terms of ion pairing.     

Determination of indican and tryptophan in normal and uraemic patients by high-performance liquid chromatography with a new electrochemical detector

A simple analytical procedure has been developed for the determination of indican and tryptophan in biological fluids by reversed-phase liquid chromatography using a new electrochemical detector consisting of a tubular anode obtained by moulding graphitized carbon black and polyethylene. The hydrodynamic voltammetry of these compounds has been carried out and it has been found that, by operating in isocratic conditions with phosphate buffer (pH 4.0)-methanol (93:7), the reported compounds can be determined directly. The procedure can be applied for the determination of the free compounds on ultrafiltered serum as well as of their total content on serum deproteinized with methanol. Levels of both compounds in normal and uraemic patients have been measured and the relative ratios between free and total content yield a useful marker for patients with renal disease. The limits of quantitation of indican and tryptophan in serum were 5 and 10 ng/ml, respectively. The within-day assay coefficient of variation for total indican and tryptophan ranged from 3.0 to 3.6% and from 3.8 to 4.1%, respectively. The day-to-day assay coefficient of variation for total indican and tryptophan ranged from 3.4 to 3.7% and from 4.6 to 5.0%, respectively.     

Electron impact mass spectrometric investigation of pyrrole mono-, di- and tri-carboxylic acids

The electron impact-induced fragmentation processes of pyrrole-2-, -3-, -2,3-, -3,4-, -2,5- and -2,3,4-carboxylic acids were investigated with the aid of metastable ion, collisional and deuterium labelling experiments. The general behaviour of these compounds is discussed in detail, together with the reasonable structures of the more relevant fragment ions.