Hydrogenation asymetrique de precurseurs d'aminoacides a l'aide de mono- et diphosphines derivees de sucres

Mono- and di-phosphines derived from sugars are synthesized and used as ligands in asymmetric catalysis. In the presence of a base (triethylamine, KOH…) the cationic complex [Rh(COD)dioxop]⁺ClO₄^?, catalyzes reduction of α-amino acid precursors with high optical yields (78–86%). The influence of the base is discussed.     

Schwefel- und Phosphorbestimmung

Ohne Zusammenfassung     

Zur Bestimmung des Adrenalins

Ohne Zusammenfassung     

Negative ion mass spectra of some unsaturated C-glycosides following keV ion bombardment

A series of anomeric unsaturated C-glycosides were studied by negative ion mass spectrometry following keV ion bombardment The compounds bearing an acidic hydrogen show a prominent [M ? H]^? peak; in the other cases, the [M ? H]^? peak is of very low intensity. A retro-Diels–Alder fragmentation and the abstraction of a hydrogen atom from the aglycon residue are observed in all cases.     

Synthesis of 2-amino-5,5-dialkyl-4-arylmethylidene-2-oxazolines from 2-alkyl-4-arylbut-3-yn-2-ols and guanidine

Reaction between 2-alkyl-4-arylbut-3-yn-2-ols and guanidine in refluxing pyridine affords 2-amino-5,5-dialkyl-4-arylmethylidene-2-oxazolines.     

“Four-component” assembly of polyaromatic 4H-cyclopenta[b]thiophene structures based on GaCl3-promoted reaction of styrylmalonates with 5-phenylthiophene-2-carbaldehyde

New “four-component” self-assembly of polyaromatic thiophene structures based on styrylmalonates and 5-phenylthiophene-2-carbaldehyde has been developed. This process is promoted by GaCl₃ and involves two [2?+?3]-annulation steps on the CHO-groups and para-substitution into one Ph-ring. The main feature of discovered process is a high diastereoselectivity with a significant increase in molecular complexity. The resulting polyaromatic structures containing two thiophene moieties in each structure have intense color and strong absorption in a near UV spectral region with absorption maxima in the range of 257–360?nm.