Voldemar Toome

Studies on the reaction of fluorescamine with primary amines

Abstract Fluorescamine is a useful reagent for the fluorometric assay of primary amines. The extent of the reaction between fluorescamine and primary amines, as well as the fluorescence intensities of the resulting fluorophors depend on pH, solvent composition and reagent concentration. Optimum values for these variables further depend on the amine under study. The influence of these parameters on the fluorogenic reaction of representative amines, and on their fluorophoric derivatives has been investigated, and the results are reported here.

aS,7S-absolute configuration of natural (−)-colchicine and allocongeners

The aS,7S‐absolute configuration of (−)‐colchicine (1) and (−)‐N‐acetylcolchinol methyl ether (3, NCME) suggested on the basis of 1H NMR data and negative Cotton effects at about 260 nm (EtOH) is firmly established by an X‐ray analysis of urea 5, a compound derived from 3. Binding of these compounds to tubulin requires an aS‐configuration of the biaryl system.

Colorimetric amino acid analysis using fluorescamine

Abstract Fluorescamine reacts efficiently with primary and secondary amino acids to form fluorescent pyrrolinone and nonfluorescent aminoenone type chromophores, respectively. A procedure is described for quantitative colorimetric determination at one fixed wavelength of the full array of natural amino acids, including proline and its derivatives. Simultaneous colorimetric-fluorometric analysis enables distinction between primary and secondary amino acids and permits their quantitative analysis with fluorescamine over a broad concentration range. These methods can also be applied for peptide analyses.

Structural determination of ascorbic acid 2-o-phosphate formed via acid hydrolysis of an ascorbic acid 3-O-phosphinate

Abstract The synthesis and X-ray structural determination of 3-O-[(bis-morpholino)phosphinyl]-5,6-O-isopropylidene- l -ascorbate (9) are described. Acid-catalyzed hydrolysis of 9 afforded the 2-O-phosphate 6. Definitive structural proof of 6 is based on a study of the pH profile of its UV spectra as compared with those of ascorbic esters, 2 and 9 (Figs. 1–3).

A Simple Simultaneous Colorimetric Determination of Primary and Secondary Amines with Fluorescamine

Abstract Primary and secondary amines react reproducibly with fluorescamine to form pyrrolinones or aminoenone type chromophores with long wavelength absorption maxima in the 375–410 and 310–320 nm regions, respectively. A simple procedure has been worked out for the simultaneous colorimetric determination of primary and secondary amines.

A simple method for determining the absolute configuration of α-amino acids

Abstract Chiral α-amino acids react with 2-methoxy - 2,4 - diphenyl - 3 (2 H ) - furanone 1 to afford N -substituted 3,5 - diphenyl - 5 - hydroxy - 2 - pyrrolin - 4 - ones 2 . The characteristic cotton effects given by these chromophoric derivatives provide a means for the determination of the absolute configuration of the parent amino acids. The longest wavelength(first) extremum in the chiroptical spectra (ORD and CD) of the l -amino acid derivatives is always positive, while it is negative for the d -amino acid derivatives.

Chiroptical properties of fluorescamine condensation compounds with α-amino acids in situ

Summary Fluorescamine reacts efficiently with primary amino acids to form pyrrolinone-type chromophores. A simple test tube procedure is described which allows in situ determination of absolute configuration of α-amino acids based on the chiroptical properties of these chromophoric derivatives.

Absolute configuration of cryptostylines I, II, and III by x-ray analysis and aromatic chirality method

Abstract The S-configuration of the alkaloids cryptostylines I, II, and III was assigned on the basis of a single crystal X-ray analysis of unnatural cryptostyline II hydrobromide (5.HBr: orthorhombic, P212121 a = 10·162, b = 12·352, c = 16·456 A) and confirmed by application of the aromatic chirality method. Further evidence for the configurational assignment was provided by the CD spectra of the monophenolic derivatives of unnatural cryptostyline II (14).

Precursors of the mammalian synthesis of morphine: (+)‐salutaridine and (−)‐thebaine from (+)‐6‐demethylsalutaridine, and (−)‐N‐13CH3‐thebaine from (−)‐northebaine

Standard samples of pure (+)‐salutaridine and (−)‐thebaine required to study the mammalian origin of morphine, were prepared from (+)‐6‐demethylsalutaridine by published procedures and were characterized by CD spectra and physical data. Reductive N‐methylation of (−)‐northebaine afforded (−)‐thebaine, and when 13C‐labeled formalin was used, (−)‐thebaine with a 13C label on the N‐methyl carbon atom resulted. The latter represents a model procedure to prepare ultimately N‐14CH3‐labeled (−)‐thebaine and 14C‐labeled congeners.

Chiroptical properties of fluorescamine condensation compounds with secondary amino acids insitu

Abstract Secondary amino acids react readily with fluorescamine to form aminoenone-type chromophores with long wavelength absorption maxima at 300–320 nm. The chiroptical properties of the reaction mixtures allow one to determine the absolute configuration of secondary amino acids in situ .