An efficient and flexible asymmetric synthesis of various 3-substituted γ-and δ-sultams is described. The key step is a diastereoselective nucleophilic 1,2-addition of various organocerium compounds to the CN double bond of ω-SAMP-hydrazonosulfonates. The resulting hydrazines were obtained in good to excellent diastereomeric excesses (de = 78 to Ն 96 %). Removal of the chiral auxiliary by reductive N,N-bond cleavage afforded the corresponding aminosulfonates without racemisation. Ester hydrolysis and subsequent treatment

An efficient and flexible asymmetric synthesis of various protected anti-1,2-sulfanyl amines bearing two adjacent stereogenic centres is described. Key steps are the diastereoselective α-alkylation of α-sulfanylated acetaldehyde-SAMPhydrazones with various electrophiles and subsequent nucleophilic 1,2-addition of organocerium reagents to the hydrazone CN double bond. The resulting hydrazines were converted into the title compounds with excellent diastereo-

A s y m m e t r i c S y n t h e s i s o f c i s -3 , 4 -D i s u b s t i t u t e d b -S u l t a m sAbstract: The asymmetric synthesis of cis-3,4-disubstituted b-sultams is reported. The protocol is based on the oxidation of 1,2-aminothiols with H 2 O 2 and ammonium heptamolybdate. The chlorination of the resulting b-amino sulfonic acids was achieved utilising a solution of phosgene in toluene. The b-aminosulfonyl chlorides obtained were cyclised to the title compounds under basic conditions without epimerisation (de, ee ≥96%) and good overall yields (17-59%). In addition, the N-Cbz-protection of b-sultams was easily accomplished.

Shear stress ramp experiments were performed in order to analyze the yield stress of the aluminium alloys AlSi5 and AlSi5Cu03Mg05Ag06 in the semi-solid state with regard to its dependency on time, solid fraction and particle size in the slurry. The experimental results were not influenced by the different chemical compositions of the alloys. The minimum solid fraction which is required for the occurrence of yield stress is called coherency solid fraction. The yield stress occurring immediately after shearing is called isostructural yield stress. At rest an internal structure is built up and the yield stress increases until the static yield stress is reached. During the transition from isostructural to static, the yield stress is called dynamic yield stress. The coherency solid fraction was estimated as a function of particle size by means of an extrapolation of the static yield stress to zero. The static yield stress is predominantly influenced by the distance between the particles which can be calculated from the particle size and the solid fraction. On the basis of dynamic yield stress measurements, the isostructural yield stress was estimated to be smaller than 10 Pa and an empirical model for the development of the dynamic yield stress was set up. Together, the experimental results allow for a complete description of yield stress as a function of particle distance and time.

Thiazine derivatives R 0610Asymmetric Synthesis of 3-Substituted γand δ-Sultams. -A variety of five-and six-membered, optically active sultams is prepared with a view to the biological activities exhibited by sulfonamide derivatives. The synthesis is based on a SAMP-hydrazone methodology. -(ENDERS*, D.; MOLL, A.; BATS, J. W.; Eur.

For Abstract see ChemInform Abstract in Full Text.

Heterocyclic 4-membered rings R 0055Asymmetric Synthesis of cis-3,4-Disubstituted β-Sultams. -Stereochemically pure title compounds (IV) are prepared in a short sequence from 1,2-aminothiol derivatives. -(ENDERS*, D.; MOLL, A.; Synthesis 2005, 11, 1807-1816; Inst. Org. Chem., RWTH Aachen, D-52074 Aachen, Germany; Eng.) -Mais 46-098