Synthese von 1, 3, 4-Oxadiazolen und 4, 5-Dihydro-1, 2, 4-triazinen aus 3-Dimethylamino-2, 2-dimethyl-2 H-azirin und Carbohydraziden

Synthesis of 1,3,4-Oxadiazoles and 4,5-Dihydro-l,2,4-triazines from 3-Dimethylamino-2,2-dimethyl-2 Hazirine and Carbohydrazides 3-Dimethylamino-2, 2-dimethyl-2 H-azirine ( 1 ) reacts with aromatic carbohydrazides to give 2-(1-amino-1-methylethyl)-5-aryl-1, 3, 4-oxadiazoles ( 7 , 10 , 11 ). With ethyl carbazate the azirine 1 forms the aminoester 15 , which is easily cyclized to the 4, 5-dihydro-1, 2, 4-triazin-3 (2H)-one 16 . From the reaction of 1 with oxamohydrazide ( 17 ) and oxalodihydrazide 19 the 4, 5-dihydro-1, 2, 4-triazin-3-carboxamide 18 and the symmetric compound 20 , respectively, have been isolated. Reactions supporting the structures of the new compounds are described.     

BINAS - synthesis and use of a new ligand for propylene hydroformylation

BINAS is a new, very efficient ligand for propylene hydroformylation. BINAS is made by the sulfonation of NAPHOS. Different synthetic routes to NAPHOS are discussed. A new two step synthesis starting from 2,2′-bis(bromomethyl)-1,1′-binaphthyl is described.     

Solubility Enhancement of Low Soluble Biologically Active Compounds by β-Cyclodextrin and Dimethyl-β-cyclodextrin

The solubility enhancement of triflumizole by complexation with -cyclodextrin and with dimethyl--cyclodextrin is compared with respect to the different physico-chemical properties of the host molecules. Although the inclusion reaction constants are rather similar for both complexation reactions, a completely different temperature dependence of the host-guest interaction is observed, which indicates a change of the reaction mechanisms. Moreover, the influence of ethanol as cosolvent is studied.     

Ein neuer Zugang zu Bicyclo[4.1.0]heptan-Derivaten

A New Approach to Bicyclo[4.1.0]heptane Derivatives The reaction of the dienone 1 with ethyl α-bromoacetate does not furnish the expected glycidic acid ester 2 but leads to the bicyclo[4.1.0]heptenone derivative 3 . The structure of this new compound has been proved by means of spectroscopic methods (1R, ¹H-NMR, ¹³C-NMR, MS). The elucidation of the configuration at C(7) could be realized by measuring a NOE effect. Other α-alkylated α-bromoacetates react with 1 in the same manner.     

The automorphism groups of the congruence group and of some of its subgroups in finite Euclidean planes

In the affine plane over a Galois field GF(q), q ; 3(4), q = p, of congruence transformations, of motions and of the generation of all point reflections respectively. Then we determine the groups AutC, AutM, AutM and obtain the following results: 1. Aut C is isomorphic to the product of the augmented group of similarities (generated by similarities, quasi reflections, quasi rotations 2) and the group of collineations which are induced by the automorphism of GF(q) operating on the coordinates. 2. AutM– AutC. 3. AutM– group of affinities of the affine space of dimension 2 over the prime field. 4. Moreover for any desarguesian affine plane Aut Dil (Dil = group of dilatations) is isomorphic to (the full collineation group).Lecture delivered at the Haifa Geometry conference 1983In my lecture I called these transformations semi-. To avoid confusion I follow here a suggestion of E. Schröder.     

Ebene algebraische Kurven vom Typ p,q

Let p,q be relatively prime integers with 2pr ^p,q be the numerical semigroup generated by p,q,{(p–1) (q–1)–1–(ip+jq)¦i+jr–2}. Then there exists a smooth projective curve X and a point x on X, such that H _r ^p,q is the set of orders of poles of the rational functions on X, which are regular on X\{x}; in other words: H _r ^p,q is a Weierstraß semigroup.     

Synthesis of 5,6-dihydro-4H-thiopyran-4-ones

The anions of 1,4-diaryl-3-buten-2-ones 1 reacts with arylisothiocyanates, yielding intermediates 4 which can ring close to 5,6-dihydro-4H-thiopyran-4-ones 5 . Under similar reaction conditions ethyl 3-oxo-4-pentenoates 7 gives the 6-spiropyrans 9 . Methylation of 3 gives the S-methylated open form 6 .     

Superstructures of temporarily stabilized nanocrystalline CaCO3 particles: morphological control via water surface tension variation

In this paper, the formation of different complex morphologies of nanocrystalline CaCO3 under the control of double hydrophilic block copolymers (DHBCs) carrying phosphate groups is described. The DHBCs consist of a poly(ethylene glycol) (PEG) block and a pendant poly[2-(2-hydroxy ethyl)ethylene] block with different degrees of phosphorylation up to 40%, some of which show surface activity. The polymers furthermore temporarily stabilize CaCO3 nanocrystals, which are formed by slow CO2 evaporation from a supersaturated Ca(HCO3)2 solution (Kitano method). The polymers are active down to concentrations of 10(-4) g/L. In dependence of the nature and concentration of the DHBC, tunable complex shuttlecock flowerlike and other superstructures are formed, which are aggregates of CaCO3 vaterite nanoparticles with an enhanced stability of at least 2 months. It is shown that the aggregation starts around template CO2 gas bubbles at the air/water interface. The size and morphology of the growing aggregates depends on the polymer concentration, phosphorylation degree, and water surface tension. The latter determines when the aggregate sinks to the bottom, interrupting the further growth process. Variation of the water surface tension by addition of the nonionic surfactant Antharox CO880 also allows a variation of the aggregate morphology, thus implying the described method as simple and versatile for the generation of complex CaCO3 morphologies.     

Using model complexes to augment and advance metalloproteinase inhibitor design

The tetrahedral zinc complex [(Tp(Ph,Me))ZnOH] (Tp(Ph,Me) = hydrotris(3,5-phenylmethylpyrazolyl)borate) was combined with 2-thenylmercaptan, ethyl 4,4,4-trifluoroacetoacetate, salicylic acid, salicylamide, thiosalicylic acid, thiosalicylamide, methyl salicylate, methyl thiosalicyliate, and 2-hydroxyacetophenone to form the corresponding [(Tp(Ph,Me))Zn(ZBG)] complexes (ZBG = zinc-binding group). X-ray crystal structures of these complexes were obtained to determine the mode of binding for each ZBG, several of which had been previously studied with SAR by NMR (structure-activity relationship by nuclear magnetic resonance) as potential ligands for use in matrix metalloproteinase inhibitors. The [(Tp(Ph,Me))Zn(ZBG)] complexes show that hydrogen bonding and donor atom acidity have a pronounced effect on the mode of binding for this series of ligands. The results of these studies give valuable insight into how ligand protonation state and intramolecular hydrogen bonds can influence the coordination mode of metal-binding proteinase inhibitors. The findings here suggest that model-based approaches can be used to augment drug discovery methods applied to metalloproteins and can aid second-generation drug design.     

Chromatographie von Carbamat- und Phenylharnstoff-Pesticiden auf Dünnschichten von basischem Zinkcarbonat

Thin layers of basic zinc carbonate can be used with good results for separation and multiple identification of carbamate and phenylurea pesticides. Five important substances could be separated by one-dimension TLC. The best results were obtained by the following developing solvents: a) benzene, b) a mixture of benzene/petroleum ether/chloroform (6∶1∶1). The substances are either recognisable in short-wave UV-light, when a fluorescence indicator (F 254 nm) is added, or in day-light, after spraying a solution of 0.1 N AgNO₃ in 3 N HNO₃, followed by an UV-exposure for about 4 min.