Insertion of the Pt(PPh3)2 unit into inorganic triatomic rings coordinated to metal—ligand moieties

Reaction of the [(triphos)Co(E₂S)]BF₄ complexes (triphos = 1,1,1-tris(di-phenylphosphinomethyl)ethane, E = P or As) containing the P₂S or As₂S cyclic units trihapto(η³-bonded to the metal, with (C₂H₄)Pt(PPh₃)₂ involves insertion of the Pt(PPh₃)₂ moiety into a bond of the inorganic ring, yielding the compounds [(triphos)Co(E₂S)Pt(PPh₃)₂]BPh₄ (E = P or As), whose structures have been determined by X-ray diffraction studies.     

Ab initio valence bond calculations. I. Methylene

An ab initio valence bond (VB ) method for calculating energies and wave functions for simple electronic systems is described and the results of its application to methylene are given together with extensive comparisons with previous theoretical results.     

Synthesis of new enantiomerically pure C1- and C2-symmetric N-alkyl-benzimidazolium and thiazolium salts

Starting from the commercially available enantiopure (1S,2S)-2-amino-1-phenyl-1,3-propanediol novel enantiomerically pure benzimidazoles were prepared; N-alkylation gave chiral benzimidazolium salts, which were tested in asymmetric benzoin condensations. The synthesis of conceptually new, enantiomerically pure, C₂ symmetric bis-thiazolium and bis-benzimidazolium salts was also developed. These new chiral heterocycles were employed as catalysts in the asymmetric dimerisation of benzaldehyde to give benzoin with moderate enantioselectivity.     

Diastereoselective synthesis of 2-substituted-piperidin-4-ones as convenient precursors for an asymmetric approach to carbacephams

Optically active carbacephams can be efficiently prepared generating the β-lactam ring on 2-substituted-piperidin-4-ones. These can, in turn, be prepared diastereoselectively through a Michael-Michael reaction sequence initiated by benzylamine on precursors derived by Wittig reaction between serinals and 4-[(4-methylphenyl)sulfonyl]-1-(triphenylphosphoranylidene)-2-butanone.     

A new nitrile oxide based synthesis of the antitumor agent geiparvarin

Geiparvarin 1 has been synthesized utilizing the 3,5-disubstituted isoxazole 8 as protected synthon for the 3(2h)furanone system, the desired α′-hydroxy-1,3-diketone precursor being eventually revealed by Mo(CO)₆ promoted reductive cleavage.     

Casein phosphoproteome: identification of phosphoproteins by combined mass spectrometry and two-dimensional gel electrophoresis

We report a fast and easy-to-use procedure that combines polyacrylamide gel electrophoresis with matrix assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF) and nanoelectrospray-tandem mass spectrometry (nES-MS/MS) analysis for the identification of casein components and defined phosphorylated sites. This methodology ensured identification of more than 30 phosphorylated proteins, five beta-, fifteen alpha(s1)-, ten alpha(s2)-, and four kappa-casein (CN) components, including nonallelic, differently phosphorylated, and glycosylated forms. The sugar motif covalently bound to kappa-CN was identified as chains, trisaccharide GalNAc, Gal, NeuGc, and tetrasaccharide 1GalNAc, 1Gal, 2NeuGc. Also identified was a biantennary chain made up of both chains of trisaccharide 1GalNAc, 1Gal, 1NeuGc, and tetrasaccharide 1GalNAc, 1Gal, 2NeuGc moiety on a single kappa-CN component. The phosphate group on site Ser12 of tryptic peptide 8-22 of most phosphorylated alpha(s1)-CN (11 phosphate groups) was localized and the oligosaccharide sequence of the main tryptic glycopeptides of two kappa-CN components was determined by means of MS/MS analysis.