Władysław Boczoń

Mass spectrometry of bisquinolizidine alkaloids : 2- and 15-substituted derivatives of sparteine and 2- (or 14)-dehydrosparteine

The mass spectral fragmentations of 2-phenylsparteine, 2-(p-tolyl)sparteine, 15-phenylsparteine, 2-phenyl-2-dehydrosparteine, 2-(p-tolyl)-2-dehydrosparteine and 15-phenyl-14-dehydrosparteine were investigated. Fragmentation pathways, elucidation of which was assisted by accurate mass measurements and correlation between the abundances of the M+• and the selected fragment ions of investigated compounds, are discussed. The data obtained create the basis for distinguishing structural isomers.

Further studies on the chemistry and structure of n-oxides of sparteine and its derivatives—V: Synthesis and structure of 2-phenylsparteine-n16-oxide,a new case of “sponge” proton

Abstract The synthesis of 2-phenylsparteine-N16-oxide (7) and its perchlorate salt (7-H+) was carried out. On the basis of spectral data, and by comparison with appropriate sparteine-N-oxides, the mechanism of formation and the structures of the two new compounds were proposed. It was found, the basicity of the new N-oxide is unexpectedly high and comparable to the basicity of quaternary ammonium hydroxides. The structure and the strength of intramolecular H-bond in 7-H+ makes 7 an excellent “catcher” proton or specific ”sponge” proton.

Mass spectrometry of bis-quinolizidine alkaloids: 2- and 17-alkyl-substituted derivatives of sparteine and lupanine

The mass spectral fragmentations of 2-methylsparteine (1), 2, 17-dimethylsparteine (2), 2-methyl-17-isopropylsparteine (3), 2-methyl-17-oxosparteine (4), 2-oxo-17-methylsparteine (17-methyllupanine) (5) and 2-oxo-17-isopropylsparteine (17-isopropyllupanine) (6) were investigated. Fragmentation pathways, whose identification was assisted by accurate mass measurements and a correlation between the abundances of the M(+.) and selected fragment ions of the investigated compounds, are discussed. The data obtained create the basis for distinguishing the structural isomers and metamers.

Further studies on the stereochemistry of sparteine, its isomers and derivatives XXIV. 2-(p-tolyl)sparteine and its monoperchlorate salt

Abstract Synthesis of 2-(p-tolyl)sparteine (VII), its monoperchlorate salt (VII-H + ) as well as its deuterated analogs was performed. Their IR and 13 C-NMR spectra were analysed to determine the structure of these compounds and the substituent and protonation effects. Properties of VII were discussed on the basis of the analysis of the pK′ MCS data.

Some stereochemical aspects of bisquinolizidine alkaloids sparteine type

This review presents some considerations on the influence of inter- and extramolecular factors of bisquinolizidine alkaloids on their stereochemistry, chemical and physicochemical properties/also : proton-acceptor/ and configurational-conformational equilibria

Conformation of some sparteine N-16 oxides revisited

Sparteine N-16 oxides were thought to occur in all chair conformations with cis fusion between their C and D rings. NMR spectral analysis made possible indication of the chair – chair – boat– chair form with cis fussion of C, D rings for sparteine, 2phenyl- and 2-methylsparteine N-16 oxides. Molecular energy found by means of DFT, Hartree– Fock, AM1, PM3 methods supported this new shape of bisquinolizidine skeleton. q 2002 Elsevier Science B.V. All rights reserved.

Further studies on the stereochemistry of sparteine, its isomers and derivatives: Part XXIII. 13C NMR analysis of sparteine derivatives substituted in external rings — disalts

Abstract The 13 C NMR spectra of six sparteine derivatives were analysed. In four of them, the substituent phenyl, methyl or cyano was in the external A ring of the molecule at C(2), while in the other two, the substituent was attached to C(15) in ring D. The analysis was based on a comparison of the spectra of the studied monocations with the spectra of the sparteine monocation taken under the same conditions, including the off-resonance spectra. This work was aimed at determining the character of the changes in the chemical shift (substituent and protonation effects), to provide a greater insight into the configurational—conformational changes of the sparteine skeleton in CD 3 CN solution. All the analysed derivatives adopt the all-chair trans -A/B: cis :-C/D bis-quinolizidine skeleton.

The steric structure of multiflorine methylation products

SummaryMultiflorine (1) — a minor lupine alkaloid — treated by methyl lithium or methyl magnesium iodide affords 4S-4-hydroxy-4-methyl-2,3-didehydrosparteine (2) and 2S-2-methyl-4-oxosparteine (3), respectively, as the dominating products. Their steric structure, determined by1H and13C NMR techniques, points to stereospecific preferences of these reactions. The observed nucleophilic 1,2- and 1,4-additions indicate that regiospecificity of the action of MeLi or MeMgI on multiflorine is different from that of the so far known similar alkylation of other enamino ketones.ZusammenfassungMultiflorin (1), ein Lupin-Nebenalkaloid, ergibt bei Umsetzung mit Methyllithium oder Methylmagnesiumiodid 4S-4-Hydroxy-4-methyl-2,3-didehydrospartein (2) und 2S-2-Methyl-4-oxospartein (3) als Hauptprodukte. Ihre NMR-spektroskopisch (1H und13C) aufgeklärte räumliche Struktur weist auf eine Stereoselektivität der erwähnten Reaktionen hin. Die beobachteten nucleophilen 1,2- und 1,4-Additionen zeigen, daß sich die Regiospezifität der Einwirkung von MeLi oder MeMgl auf Multiflorin von jener bis jetzt bekannter Alkylierungen von Enaminoketonen unterscheidet.

Further studies on the stereochemistry of sparteine, its isomers and derivatives: Part XIV. Synthesis, structure and spectroscopic properties of the 2-phenyl-2-dehydrosparteine and its di-protonated salts (chloride, bromide and perchlorate)

Abstract The synthesis of 2-phenyl-2-dehydrosparteine (III) has been repeated and improved. The three crystalline salts : III , were obtained and characterized. From IR spectra, the structure of these salts, and the mode of the protonation of III, was determined. The free base (III) as well as its diprotonated salts (chloride, bromide and perchlorate) preserve the same configurational and conformational system, i.e. trans A/B, chair/chair - trans C/D, boat/chair. Significant differences in the stretching vibrations of the phenylimmonium group in the IR spectra of diperchlorate and other salts of III are discussed in the terms of hypothetical (electronic structure) mesomeric forms of diprotonated cations of III.

Crystal and molecular structure of 2-phenylsparteine perchlorate

The structure of the title compound has been solved: it comprises two ionic components. The cation skeleton is built of two quinolizidine moieties with atrans A/B and acis C/D configuration. All four heterocyclic rings adopt a chair conformation. Owing to an N(16) protonation, an intramolecular hydrogen bond has been formed with an N(1)⋯N+(16) distance of 2.742(4) Å. The protonation and subsequent hydrogen-bond formation are the main factors that cause an inversion of the N(16) configuration. The phenyl substituent at C(2) has weakened the intramolecular hydrogen bond in comparison with that of the 2-methylsparteine cation. The ClO4− anions are disordered with occupancy factors of 0.70 and 0.30.