Poly­sulfonyl­amines. CLXXI. [Di­(methane­sulfonyl)­amido‐κN]­bis(2‐picoline‐κN)copper(I)

The title compound, [Cu(C₂H₆NO₄S₂)(C₆H₇N)₂], consists of monomeric mol­ecules in which the Cu atom displays planar but irregular coordination by three N‐atom donors; Cu—N = 2.1054 (12) (amide N), 1.9514 (12) and 1.9589 (12) Å, and N—Cu—N = 141.24 (5), 111.54 (5) and 107.20 (5)°. Intramolecular Cu⋯O contacts are observed. The packing involves (interconnected) layer formation via C—H⋯O interactions in two directions, three hydrogen bonds combining to form layers parallel to (101) and five to form layers parallel to (10).     

Microbial and Enzymatic Synthesis of Optically Pure D- and L-3-Trimethylsilyl-alanine by Deracemization of D,L-5-Trimethylsilyl-methyl-hydantion

Summary.  The sterospecificities of hydantoinases and N-carbamoyl amino acid amidohydrolases (N-carbamoylases) from different microbial sources were investigated for the stereoselective syntheses of the unnatural silicon-containing amino acids D- and L-3-trimethylsilyl-alanine (3) from the respective racemic hydantoin D,L-1. In a preparative biotransformation, whole resting cells of Agrobacterium sp. IP I 671, immobilized in a Ca-alginate matrix, were used for the synthesis of amino acid D-3 in 88% yield and 95% enantiomeric excess. Since the purified D-N-carbamoylase from Agrobacterium sp. IP I 671 was shown to be 100%D-selective, the enantiomeric purity of 95% of D-3 arising from the transformation with the immobilized cells must be explained by the participation of a further, L-selective N-carbamoylase or, which is more likely, by racemization of the final hydrolysis product by the action of an amino acid racemase. Isolated hydantoinases from Bacillus thermoglucosidasius, Thermus sp., Arthrobacter aurescens DSM 3745, and Arthrobacter crystallopoietes DSM 20117 turned out to be stereospecific for the conversion of the D-form of hydantoin D,L-1. The enantiomerically pure L-form of 3 was also prepared. It was synthesized from racemic N-carbamoyl amino acid D,L-2 by enantiomer-specific hydrolysis of the L-form in presence of L-N-carbamoylase from Arthrobacter aurescens DSM 3747. Received December 20, 1999. Accepted January 7, 2000     

SESAME – ein Traum nimmt Gestalt an

Als vor zehn Jahren die ersten Diskussionen über ein Zentrum für Synchrotronstrahlung im Mittleren Osten begannen, hielten dies viele für ein aussichtsloses Unternehmen – nicht zuletzt wegen der angespannten politischen Situation. In den letzten Jahren wurden jedoch so große Fortschritte erzielt, dass das Projekt SESAME (Synchrotron‐light for Experimental Science and Applications in the Middle East) auf einem guten Weg ist. Am 3. November soll das in Allaan, Jordanien, stehende Gebäude offiziell eingeweiht werden. Die Inbetriebnahme der Anlage ist für Ende 2011 geplant.     

Site-selective direct arylation of unprotected adenine nucleosides mediated by palladium and copper: insights into the reaction mechanism

Reaction conditions facilitating the site-selective direct aryl functionalisation at the C-8 position of adenine nucleosides have been identified. Many different aromatic components may be effectively cross-coupled to provide a diverse array of arylated adenine nucleoside products without the need for ribose or adenine protecting groups. The optimal palladium catalyst loading lies between 0.5 and 5 mol %. Addition of excess mercury to the reaction had a negligible affect on catalysis, suggesting the involvement of a homogeneous catalytic species. A study by transmission electron microscopy (TEM) shows that metal containing nanoparticles, ca. 3 nm with good uniformity, are formed during the latter stages of the reaction. Stabilised PVP palladium colloids (PVP=N-polyvinylpyrrolidone) are catalytically active in the direct arylation process, releasing homogenous palladium into solution. The effect of various substituted 2-pyridine ligand additives has been investigated. A mechanism for the site-selective arylation of adenosine is proposed.