Volume 36, Issue 10
Currently known as: Angewandte Chemie International Edition
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199710211
The cover picture shows a representation of organic–inorganic films containing well-organized layers of a polyoxometalate Keggin anion and a cationic surfactant. This new kind of supramolecular assembly has been obtained by using the Langmuir–Blodgett technique, and, considering the photochemical, electrochromic, magnetic, and catalytic properties associated with these metal-oxide clusters, it opens a wide range of new possiblities for applications. More about these organic–inorganic films is reported by E. Coronado and C. Mingotaud et al. on pages 1114ff.
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199710231
Prof. Dr. Ian D. Spenser and Prof. Dr. Robert L. White
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199710321
Even though more than half a century has elapsed since the isolation of Vitamin B1 (thiamin, 1), the determination of its structure, and the elucidation of its biochemical function, present day understanding of its biosynthesis is still incomplete. This review summarizes the current state of knowledge of thiamin biosynthesis, based on investigations with isotropic tracers and on genetic studies.
Prof. Dr. Wolfgang A. Herrmann and Prof. Dr. Boy Cornils
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199710481
Less apodictic! That homogeneous and heterogeneous catalysis will be better integrated with one another in the future is certain when one peruses the developments of the past few years. Tailor-made homogeneous and surface-bound catalysts, multiple-component catalysts, and electroenzymatic processes are just a few of the advances that will bridge the gap between the “two-cultures”. An approach to unification can be seen in research as well as industry. Catalysis is a central theme in chemical research.
Dr. Michael A. Walker
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199710691
Orthogonal and native chemical ligation are two terms of a novel method for synthesizing proteins. It is particularly useful where molecular biology techniques fail, for example, for the synthesis of analogs of natural proteins from unnatural building blocks. Since the innovative method proceeds without carboxyl-group activation or side-chain protection, it is very easy to use and will find application by the average organic chemist.
Prof. Dr. Hans-Jörg Schneider
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199710721
How can meaningful values be determined for the energies of weak interactions? That this is not a trivial question is revealed by the printed correspondence, which is concerned with the correct choice of model and method for the analysis of π-π interactions between aromatic rings with the help of complexes such as 1.
Dr. Christopher A. Hunter
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199710731
Prof. Dr. Ulrich Schmidt
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199710741
Fourteen-membered cyclopeptides are strained (J. Zhu) or only rigid (U. Schmidt) and therefore difficult to prepare. However, in the opinion of U. Schmidt the degree of novelty of the work by Zhu et al. is less than the latter claim, while Zhu regards their success in avoiding the ring opening of 1 by an attack of a base as a remarkable feature of their synthesis.
Dr. Jieping Zhu
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199710742
Pamela C. Ohara, Prof. James R. Heath and Prof. William M. Gelbart
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199710781
Thousands of individual metal nanocrystals with a diameter of 2.5 nm form the five particle rings shown in the transmission electron microscope image on the right. Each ring has a diameter of about 1 μm. The experimental and theoretical explanation for these rings are discussed.
Dr. Tobias Vossmeyer, Erica DeIonno and Prof. Dr. James R. Heath
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199710801
How can patterned thin films of nanocrystals be self-assembled? This contribution describes a general strategy that combines biochemical and lithographic techniques to restrict the assembly of nanocrystals to parts of a surface previously exposed to UV/Vis irradiation. The scanning electron microscope image on the right shows a pattern of gold nanoparticles assembled on a silicon substrate.
Vasilis Tangoulis, Dr. Catherine P. Raptopoulou, Sofia Paschalidou, Prof. Dr. Evangelos G. Bakalbassis, Prof. Dr. Spyros P. Perlepes and Dr. Aris Terzis
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199710831
A chair-within-a-chair arrangement of the twelve copper atoms (bottom left) is characteristic of one of the complexes reported here; the other complex features two Cu tetrahedra sharing a common vertex (bottom right). Both were isolated from the reaction mixture [Cu2(O2CMe)4(H2O)2]/(py)2CO in MeCN. Magnetic susceptibility data show that the heptanuclear complex has an S = 1/2 ground state.
Masahiro Okuyama and Prof. Dr. Takashi Tsuji
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199710851
The benzene ring is nonplanar but sustains significant aromatic ring current in paracyclophane 1. The strained skeleton of this molecule was kineticaly stabilized by substituents, which permitted the measurement of the 1H NMR spectrum of a paracyclophane for the first time.
Dr. Sandeep S. Dhingra, Dong-Kyun Seo, Glen R. Kowach, Dr. Reinhard K. Kremer, Dr. Julie L. Shreeve-Keyer, Dr. Robert C. Haushalter and Prof. Myung-Hwan Whangbo
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199710871
Metal atoms in isolated chains are the sole components of the first quaternary Zintl anion [Au(Ag1-xAux)2Sn2Te9]-4 (x = 0.32; structure of depicted below) in the compound (Et4N4)[Au(Ag1-xAux)2Sn2Te9]. Electronic structure calculations and the diamagnetic and semiconducting properties of of this new compound show that the anion displays a Peierls distortion at room temperature.
Prof. André B. Charette and Jacinthe Lemay
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199710901
Substituted, functionalized iodoalkylzinc reagents in combination with the chiral dioxaborolane 2 give excellent diastereo- and enantiomeric selectivities in cyclopropanations when substituted allyl alcohols 1 (R1 H, Et, CH2OBn; R2 H, Ph, nPr; R3 H, Me) are used as starting materials and CH2Cl2 as solvent. This efficient preparation of chiral, nonracemic 1,2,3-trisubstituted cyclopropanes 3 might be useful in natural product synthesis.
Sylvie Fabre, Prof. Philippe Kalck and Dr. Guy Lavigne
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199710921
An ususual migration of the alkyl group away from the CO bond of added formate leads to strictly stereospecific formation of the stable ehtyl complex 2 when the catalytic addition of ethyl formate to ethylene (catalyst = 1) is terminated by freezing. Both ethylene and the alkyl formate act as sources of the alkyl groups and can thus be used for CC bond-forming reactions below ambient temperature. PPN+ = (Ph3P)2N+.
Dr. Rainer Streubel, Dipl.-Chem. Markus Hobbold, Dipl.-Chem. Jörg Jeske and Prof. Dr. Peter G. Jones
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199710951
Unexpected reactivity of in situ generated carbene complex anions in seen upon treatment with a P-chloro(methylene)phosphane. A stereoselective PC coupling reaction provides the η1-2-phosphabutadiene complexes 1a,b. Thermal isomerization of these compounds leads to the novel η1-2,3-dihydrophosphete complexes 2a,b. a: M Cr; b: M W.
Dr. Michael Davies and Dr. Mark Bradley
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199710971
Conventional solid-phase synthesis and a novel inversion step allows ready access to peptides modified at the C-terminus (the principle is outlined below). These compounds have important biological roles and a wide range of applications in research.
Frank Bordusa, Dr. Dirk Ullmann and Prof. Dr. Hans-Dieter Jakubke
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199710991
Not possible with chemical methods: Protein synthesis from the N- to C- terminus using the reverse hydrolysis potential of proteases was accompolished for the model petide 1. The stereo- and regiospecificity of the enzymes used ensured integrity of the stereogenic center and allowed ecological reaction conditions without side-chain protection.
Dr. Michael J. Marsella, Heather D. Maynard and Prof. Robert H. Grubbs
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199711011
A highly efficient combination: template directing and olefin metathesis. The polyether dienes 1 react in good yields to give crown ethers 2 in the presence of LiClO4 and the Ru catalyst 3 (Cy = cyclohexyl). Ring-opening metathesis polymerization (ROMP) of the cyclic olefins 2 results in polymers that are capable of regenerating 2 by template-directed methathesis depolymerization.
Dr. Andreas Harthun, Dr. Renat Kadyrov, Prof. Dr. Rüdiger Selke and Prof. Dr. Joachim Bargon
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199711031
The PHIP-NMR method (PHIP = parahydrogen induced polarization) can be used to detect dihydride catalyst–substrate complexes of the general formula [Rh(PP)(XX)(H)2]BF4 (shown on the right, XX = dimethyl itaconate as substrate), which are formed in situ under hydrogenation conditions with chiral bis(phosphinite)rhodium(I) catalysts. Remarkable is the absence of typical (H,P)trans coupling (2J(H,P)trans); the RhP bond trans to HB is therefore lenthened, and the octahedral geometry distorted.
Dipl.-Chem. Roland Fleischer, Alexander Rothenberger and Prof. Dr. Dietmar Stalke
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199711051
The nitrogen analogue of the sulfate ion, tetraimidosulfate S(NR) is easily accessible from S(NR)3 and LiN(H)R. S(NR)3 can be prepared from S(NR)2 and LiN(H)R by oxidation of the resulting [Li2(NR)3S]2 with bormine or iodine. In an addition reaction organolithium compounds and S(NR)3 yield the related triimidosulfonate RS(NR). Both anions form molecular contact ion pairs with lithium cations (structure of S(NR) shown on the right, the thf ligands on Li1 and Li2 have been omitted), which makes them promising ligands in coordination chemistry.
Dr. Markus Altmann, Dipl.-Chem. Gaby Roidl, Priv.-Doz. Dr. Volker Enkelmann and Dr. Uwe H. F. Bunz
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199711071
Conditions of flash vacuum pyrolysis (FVP) result in the conversion of bisdiyne 1 into the complexed, tetraethynylated cyclobutadiene 2, which is isolated as the sole product in high yield. Complex 2 can be protected, and both the partially as well as the fully deprotected, complexed, tetraethynylated cyclobutadienes are stable under ambient conditions. TIPS = triisopropylsilyl.
Prof. Dr. Ulrich Schmidt, Dr. Karin Neumann, Dr. Andreas Schumacher and Dr. Stefan Weinbrenner
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199711101
A cyclopeptolide, a polyene, and an aminoreductone—species with completely different biogenetic origins—are the components of the antibiotically active natural product enopeptin B (1, see schematic representation below), which is particularly active against Staphylococcus aureus. The first total synthesis of this compound, which belongs to a new class of substances, was achieved by the clever use of the arsenal of methods available to modern peptide chemistry. The three basic units were coupled by two different routes.
Dipl.-Chem. Michael Mehring, Dr. Markus Schürmann, Prof. Dr. Hans Reuter, Prof. Dr. Dainis Dakternieks and Prof. Dr. Klaus Jurkschat
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199711121
Pillar-shaped organostannoxanes with the first triple-ladder structure of type A are obtained in almost quantitative yield by reaction of the tritin compound [RCl2Sn(CH2)3]2SnCl2 with (tBu2SnO)3. In contrast, treating [RCl2Sn(CH2)3]2SnCl2SiMe with (tBu2SnO)3 affords an organostannoxane with a folded double-ladder structure. R CH2SiMe3.
Miguel Clemente-León, Dr. Christophe Mingotaud, Dr. Bóatrice Agricole, Dr. Carlos J. Gómez-Garcia, Prof. Dr. Eugenio Coronado and Dr. Pierre Delhaès
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199711141
A new method for the synthesis of inroganic—organic composites with promising properties is the incorporation of polyoxometalates into well-ordered organic films by the Langmuir–Blodgett (LB) method. The structure of such an LB film is depicted schematically on the right.
Prof. Dr. Bernd Wrackmeyer, Dipl.-Chem. Hans-Jörg Schanz and Dr. Wolfgang Milius
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199711171
The first polyborane with six heteroatoms (3) is formed when the new tetracarba-nido-octaborane(8). (2), readily available by the reaction of 1 with Et2BH, reacts with [Fe3(CO)12].
Jörg Andreas Schröter, Prof. Dr. Carsten Tschierske, Prof. Dr. Michael Wittenberg and Prof. Dr. Joachim Heinz Wendorff
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199711191
Rodlike 4,4″-didecyloxy-p-terphenyl derivatives with a laterally attached crown-6 moiety form columnar, liquid-crystalline phases in the presence of aqueous potassium salt solutions. The building block is shown on the right.
Dr. Ulrich Simon, Prof. Dr. Ferdi Schüth, Dipl.-Chem. Stephan Schunk, Dr. Xiqu Wang and Prof. Dr. Friedrich Liebau
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199711211
The natural mineral cetineite was prototype for the synthesis of the compound 1. Its nanoporous, template-free host structure is an idela object for numerous investigations. Electronic excitation and transport processes, for example, can be studied on this nanostructured semiconducting material. A part of the crystal structure is shown on the right.
Prof. Dr. Lutz F. Tietze and Dipl.-Chem. Hartmut Schirok
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199711241
Interesting for cancer therapy: The unique pentacyclic alkaloid cephalotaxine is the parent compound of the strongly cytotoxic harringtonines, which are isolable from the study-east Asian yewtree. Now the cephalotaxine precursor 2 has been synthesized highly efficiently and selectively in two steps from the readily accessible amine 1 through an intramolecular Pd-catalyzed allylic amination to form the spirocycle (85% yield) and subsequent Heck reaction to construct the seven-membered ring (80% yield).
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199711271
Robert J. Cernik
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199711281
Jörg August Becker
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199711291