Transition‐Metal‐Catalyzed Direct Arylation of (Hetero)Arenes by C?H Bond Cleavage

The area of transition‐metal‐catalyzed direct arylation through cleavage of C? H bonds has undergone rapid development in recent years, and is becoming an increasingly viable alternative to traditional cross‐coupling reactions with organometallic reagents. In particular, palladium and ruthenium catalysts have been described that enable the direct arylation of (hetero)arenes with challenging coupling partners—including electrophilic aryl chlorides and tosylates as well as simple arenes in cross‐dehydrogenative arylations. Furthermore, less expensive copper, iron, and nickel complexes were recently shown to be effective for economically attractive direct arylations.     

Cover Picture: A Phosphorus Analogue of Bis(η4‐cyclobutadiene)iron(0) (Angew. Chem. Int. Ed. 17/2009)

A rare phosphorus analogue of the elusive complex bis(η⁴‐cyclobutadiene)iron(0) is reported by K. Lammertsma et al. in their Communication on page 3104 ff. The background of the cover picture shows John Montagu (1718–1792), 4th Earl of Sandwich and 1st Lord of the Admiralty, who certainly would not have dreamt that an important class of organometallic compounds, sandwich complexes, would bear his name one day. The synthesis of [Fe(P₂C₂tBu₂)₂] shows that sandwich complexes are still topical objects of research.

     

Thanks to reviewers in 2009

Acknowledgement to Referees

Thanks to reviewers in 2009     

Orbits of parabolic subgroups on metabelian ideals

Let k be an algebraically closed field, t∈Z?1, and let B be the Borel subgroup of GLt(k) consisting of upper-triangular matrices. Let Q be a parabolic subgroup of GLt(k) that contains B and such that the Lie algebra qu of the unipotent radical of Q is metabelian, i.e. the derived subalgebra of qu is abelian. For a dimension vector with , we obtain a parabolic subgroup P(d) of GLn(k) from B by taking upper-triangular block matrices with (i,j) block of size di×dj. In a similar manner we obtain a parabolic subgroup Q(d) of GLn(k) from Q. We determine all instances when P(d) acts on qu(d) with a finite number of orbits for all dimension vectors d. Our methods use a translation of the problem into the representation theory of certain quasi-hereditary algebras. In the finite cases, we use Auslander-Reiten theory to explicitly determine the P(d)-orbits; this also allows us to determine the degenerations of P(d)-orbits.     

The <Emphasis Type="Italic">k</Emphasis>-domatic number of a graph

Let k be a positive integer, and let G be a simple graph with vertex set V (G). A k-dominating set of the graph G is a subset D of V (G) such that every vertex of V (G)-D is adjacent to at least k vertices in D. A k-domatic partition of G is a partition of V (G) into k-dominating sets. The maximum number of dominating sets in a k-domatic partition of G is called the k-domatic number d _k (G). In this paper, we present upper and lower bounds for the k-domatic number, and we establish Nordhaus-Gaddum-type results. Some of our results extend those for the classical domatic number d(G) = d ₁(G).      

Resolution of 1,1′-Binaphthyl-2,2′-Dicarboxylic Acid with Quinine: Structure of the Intermediate (<Emphasis Type="Italic">S</Emphasis>)-1,1′-Binaphthyl-2,2′-Dicarboxylate Dihydrate Diastereomeric Salt

Abstract  

Racemic 1,1′-binaphthyl-2,2′-dicarboxylic acid (BNDA) was resolved using quinine as the resolving agent. The structure of the resultant quininium (S)-1,1′-binaphthyl-2,2′-dicarboxylate dihydrate salt (1) was elucidated. The asymmetric unit contained one 1,1′-binaphthyl-2,2′-dicarboxylate anion, two quininium cations and two water molecules. The structure was solved successfully in the orthorhombic space group P2₁2₁2₁ with unit cell dimensions: a = 11.100(2) ?, b = 16.572(3) ?, c = 28.726(6) ?.     

On the supremum of some random Dirichlet polynomials

We study the average supremum of some random Dirichlet polynomials D _N (t) = Σ _n=1 ^N ? _n d(n)n ^?σ?it , where (? _n ) is a sequence of independent Rademacher random variables, the weights d(n) satisfy some reasonable conditions and 0 ≦ σ ≦ 1/2. We use an approach based on methods of stochastic processes, in particular the metric entropy method developed in [8].     

Numerical investigations on the fixation of cemented and uncemented endoprostheses

In this contribution, a constitutive model adopted from the computational plasticity-models of Drucker-Prager and von Mises is presented. This model captures the material behavior of osseointegration and the curing-process of bone cement. With this basic model, both simulations of bone-ingrowth of uncemented implants and simulations of the curing process of bone cement for cemented implants are carried out in a bone-implant interface. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Dirichlet forms for singular one-dimensional operators and on graphs

We treat the time evolution of states on a finite directed graph, with singular diffusion on the edges of the graph and glueing conditions at the vertices. The operator driving the evolution is obtained by the method of quadratic forms on a suitable Hilbert space. Using the Beurling–Deny criteria we describe glueing conditions leading to positive and to submarkovian semigroups, respectively.     

Twin probes as a novel tool for the detection of single-nucleotide polymorphisms

Single-nucleotide polymorphisms (SNPs) are the most common form of DNA sequence variation. There is a strong interest from both academy and industry to develop rapid, sensitive and cost effective methods for SNP detection. Here we report a novel structural concept for DNA detection based on fluorescence dequenching upon hybridization. The so-called "twin probe" consists of a central fluorene derivative as fluorophore to which two identical oligonucleotides are covalently attached. This probe architecture is applied in homogeneous hybridization assays with subsequent fluorescence spectroscopic analysis. The bioorganic hybrid structure is well suited for sequence specific DNA detection and even SNPs are identified with high efficiency. Additionally, the photophysical properties of the twin probe were investigated. The covalent attachment of two single stranded oligonucleotides leads to strong quenching of the central fluorescence dye induced by the nucleobases. The twin probe is characterized by supramolecular aggregate formation accompanied by red-shifted emission and broad fluorescence spectra.