Asymmetric alkylation of diarylmethane derivatives. Improved results using methoxyethoxy substituent

Alkylation of 2-methoxyethoxyphenyl phenyl methane using sec-BuLi and (−)-sparteine has been carried out in excellent yields and up to 94% ee. The best results were obtained in allylation reactions but methylation, ethylation, benzylation and trimethylsilylation have all been carried out with acceptable ee.     

Synthesis of new 2-oxosparteine derivatives

For the first time, substituents to the 3-position of 2-oxosparteine have been introduced. The synthesis of 3-phenylthiolupanine, 3,3-di(phenylthio)lupanine, 3-dehydrolupanine, 3-bromodehydro-lupanine and 2-thiono-3-dehydrosparteine has been described. The stereochemistry of these compounds has been determined and by NMR spectroscopy and X-ray crystallography.     

Effect of hydroxy groups on conformational equilibrium in bis-quinolizidine systems

A review of the 99 ¹³C NMR spectra of 72 hydroxy, methoxy or ester derivatives of alkaloids with the sparteine skeleton has been made. An improved method of determination of the conformer fractions in conformational equilibria in bis-quinolizidine compounds of sparteine type has been used to estimate the energy of the hydroxy group effect at various positions. The effect can be explained by intermolecular hydrogen bonds.     

Products of the reactions of sparteine-2-thione with CuBr2 in protic and aprotic solvents

Reactions of copper(II) bromide with racemic sparteine-2-thione (SSp) in a 1:1 M ratio yielded two new complexes, whose structures depend on the solvent used. In acetonitrile, the reaction product is a sulfur-bridged dinuclear [CuBr₂(μ-SSp)]₂ complex (1) in which sparteine-2-thione acts as a bridging S-ligand, while in methanol it is a CuBr₂ complex (2) with sparteine deprived of the A-ring. Compound 1 crystallizes as an acetonitrile solvate in a 1:2 ratio and constitutes one of a few Cu(II) doubly bridged heterocyclic thionato complexes. The disorder of the C/D bisquinolizidine fragment in the crystal of 1 reflects the ease of the conversion from the common trans boat-chair to the unprecedented cis chair-boat stereoisomer. Obtained in methanol, the sparteine surrogate (Sp(surr)), is equally effective as a chelating ligand as sparteine and its isomers, and thus can be used as an alternative diamine ligand in metal complexation. Metal coordination with Sp(surr) brings the diamine nitrogens much closer together than in any other sparteine metal complexes.     

From four to five and six coordinated sparteine and α-isosparteine mononuclear Cu(II) complexes through the carboxylate donors

Cu[(C₁₅H₂₆N₂)(OCOR)₂] complexes, where OCO is a fragment of either formato or acetato group and C₁₅H₂₆N₂ is sparteine or α-isosparteine have been synthesized and structurally characterized. The bis-formato complexes (1 and 2) display a distorted 4 + 1 coordination resulting from variable metal binding stereochemistry and function of the two formato units. The syn formato group acts as a pseudochelating bidentate while the anti conformer as a monodentate ligand. This inequivalence of the two formate ligands seems deliberate for it allows formation of the stabilizing intramolecular hydrogen bond between the CH donor belonging to the monodentate formate ligand and equatorially coordinated oxygen atom belonging to the pseudo-chelating formate ligand. At variance, the C₂ symmetrical bis-acetato complex (3) displays tetragonally elongated octahedral geometry of the CuN₂O₂O′O′ with long off-axis coordination of the second O atom from each acetate ligand in the axial position.Complexes 1-3 have been also characterized by elemental analysis, IR, UV-Vis and MS spectroscopy.     

Asymmetric alkylation of diphenylmethane derivatives using (−)-sparteine

Alkylation of 2-oxygenated diphenylmethane derivatives using sec-butyllithium and (−)-sparteine gave enantiomeric excesses of up to 60% with allyl bromide but alkylations with methyl electrophiles were poorly selective. When compounds with a free hydroxy in the 2-position were alkylated the selectivity was reversed.     

Chiral diamines for asymmetric synthesis: an efficient RCM construction of the ligand core of (−)- and (+)-sparteine

An efficient RCM-based approach was applied to the total asymmetric synthesis of a tricyclic diamine and, formally, of its enantiomer, widely known as efficient and versatile chiral ligands of the sparteine-like type.     

Crystal structures and spectroscopic properties of copper(II) pseudohalide complexes with two sparteine epimers, having a CuN4 chromophore

Tetrahedrally distorted copper(II) sparteine pseudohalide complexes having a CuN₄ chromophore were prepared and characterized by various spectroscopic techniques and X-ray crystallography. Among them, the crystal structures of copper(II) isothiocyanate complexes with two sparteine epimers, (−)-l-sparteine (Sp) and (−)-α-isosparteine (α-Sp), were determined. The N_Sp–Cu–N_Sp plane in copper(II) (−)-l-sparteine isothiocyanate [Cu(Sp)(NCS)₂] and copper(II) (−)-α-isosparteine isothiocyanate [Cu(α-Sp)(NCS)₂] is twisted by 58.2(6)° and 52.2(9)°, respectively, from the N_NCS–Cu–N_NCS plane. Based on the values of the dihedral angles and tilted distances of these two complexes, the geometry around Cu(II) in Cu(α-Sp)(NCS)₂ is more distorted from the perfect tetrahedron than that in Cu(Sp)(NCS)₂. For copper(II) sparteine pseudohalide (NCS⁻ and N₃⁻) complexes having a CuN₄ chromophore, the EPR and the optical spectral data were collected. The results of X-ray crystallography and ESR spectroscopy are in a good agreement with the assumption that the degree of distortion from planarity to tetrahedron will reduce the A_|| value of four-coordinate copper(II) sparteine pseudohalide complexes.     

Studies on the complex formation between lactams and thiolactams of sparteine with copper(II) cation

The complex formation for lactams and thiolactams of sparteine with Cu(II) cation in ethanol was studied by theoretical, kinetic and MS methods. The studied compounds with Cu(II) cation formed 1:1 and 1:2 complexes. The kinetic parameters of their formation were determined. Both kinetic and thermodynamic parameters depend strongly on the presence of oxo- or thiono-group in sparteine skeleton.     

司巴丁电化学行为的研究

在０．０５ｍｏｌ／Ｌ ＨＡｃ－０．１０ ｍｏｌ／Ｌ ＮａＡｃ（ｐＨ４．９６）底液中，司巴丁在单扫示波极谱上有一灵敏的催化氢波。导数波峰电位于－１．６５Ｖ（ｖｓ．ＳＣＥ）。司巴丁浓度在４×１０＾－７～×１０＾－６ｍｏｌ／Ｌ范围内与峰高成线性关系。检测下限为６×１０＾－８ｍｏｌ／Ｌ。本对于极谱波的性质及电极过程机理进行了较详细的探讨。