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Graphical Abstract Angew. Chem. Int. Ed. 32005

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Contents
The following Communications have been judged by at least two referees to be “very
important papers” and will be published online at www.angewandte.org soon:
H. Braunschweig,* K. Radacki, D. Rais, G. R. Whittell
The First Boryl-Bridged Complex: An Unprecedented
Coordination Mode of the BR2 Ligand
D. Enders,* C. Grondal
Direct Organocatalytic de novo Synthesis of Carbohydrates
T. Fink, H. Bruggesser, J.-L. Reymond*
Virtual Exploration of the Small-Molecule Chemical Universe
Below 160 Daltons
S. Kobayashi,* K. Arai, H. Shimizu, Y. Ihori, H. Ishitani,
Y. Yamashita
A Bimetallic Chiral Niobium Complex for Lewis Acid Catalyzed
Enantioselective Reactions: Design of a Tridentate Ligand and
Elucidation of the Catalyst Structure
C. Whitehouse,* J. Fang, A. Aggeli, M. Bell, R. Brydson,
C. W. G. Fishwick, J. Henderson, C. M. Knobler, R. W. Owens,
N. H. Thomson, D. A. Smith, N. Boden*
Adsorption and Self-Assembly of Peptides on Mica Substrates
You Seok Seo, C. Lee, K. H. Lee, K. B. Yoon*
1:1 and 2:1 Charge-Transfer Interactions between Aromatic
Hydrocarbons and Dry Titanium Dioxide
News
S. John and G. Ozin Receive Brockhouse
Canada Prize
358
Polymer Award to C. J. Hawker
358
Noyori Prize to D. Seebach
358
Books
Catalysis and Electrocatalysis at
Nanoparticle Surfaces
Andrzej Wieckowski, Elena R. Savinova,
Constantinos G. Vayenas
reviewed by R. Imbihl
359
Calculation of NMR and EPR Parameters
Martinin Kaupp, Michael Bhl,
Vladimir G. Malkin
reviewed by C. Ochsenfeld
359
Organometallics in Process Chemistry
Robert D. Larsen
reviewed by M. Brring
360
Biocatalysis: Enzymatic transformations
have become competitive methods for the
synthesis of complex organic compounds.
The wide range of possibilities offered by
biocatalysis for the synthesis of target
molecules are highlighted based on the
example of the statins. This class of
compounds, which includes rosuvastatin
(see picture), are good inhibitors of
cholesterol synthesis and dominate the
market for cholesterol-lowering drugs.
Highlights
Enzyme Catalysis
M. Mller*
362 – 365
Chemoenzymatic Synthesis of Building
Blocks for Statin Side Chains
Minireviews
Palladium Catalysts
U. Christmann, R. Vilar*
366 – 374
Monoligated Palladium Species as
Catalysts in Cross-Coupling Reactions
346
A matter of size: Lately, new catalysts
based on complexes of palladium with
electron-rich and bulky ligands have been
developed for the activation of lessreactive aryl chlorides in cross-coupling
reactions to generate C E bonds (E = C,
N, O, S). The enhanced reactivity of the
catalysts is attributed to the formation of
unsaturated [Pd0L] species (see scheme;
L = phosphines or carbenes).
2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Angew. Chem. Int. Ed. 2005, 43, 346 – 355
Angewandte
Chemie
Reviews
Like a wildcard in a card game, the
introduction of a metal into aromatic or
heterocyclic building blocks ensures a
maximum of target flexibility in the
synthesis (see scheme). It can be replaced
with a wide range of electrophiles and
thus offers a convenient access to virtually
any functionalized derivative. The ultimate objective of this “toolbox” approach
is not to miss any structural opportunity
inherent in a new substituent pattern.
Synthesis Strategies
M. Schlosser*
376 – 393
The 2 3 Toolbox of Organometallic
Methods for Regiochemically Exhaustive
Functionalization
Communications
For the USA and Canada:
ANGEWANDTE CHEMIE International
Edition (ISSN 1433-7851) is published weekly
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Meacham Ave., Elmont, NY 11003. Periodicals
Angew. Chem. Int. Ed. 2005, 43, 346 – 355
Which way to turn? For the very first time,
a linear dipeptide has been shown to
accommodate two consecutive g turns in
the solid state. An aminocyclopropane
carboxylic acid has overridden the tendency of proline to induce a b-turn conformation in Pro-Xaa dipeptides (see X-ray
crystal structure; blue: N, red: O, dashed
lines show H bonds).
Peptide Structures
Yanking chains and rattling cages:
Depending on their radius of gyration,
molecules either retain or lose their ability
to rotate inside zeolite cages (see picture).
Such differences in rotational adsorption
entropy result in a preferential uptake of
branched alkanes over their linear structural isomers in zeolites such as MCM-22
which allows the separation of the two
types of molecules.
Molecular Separations
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A. I. Jimnez,* G. Ballano,
C. Cativiela
396 – 399
First Observation of Two Consecutive
g Turns in a Crystalline Linear Dipeptide
J. F. M. Denayer,* R. A. Ocakoglu,
I. C. Arik, C. E. A. Kirschhock,
J. A. Martens, G. V. Baron
400 – 403
Rotational Entropy Driven Separation of
Alkane/Isoalkane Mixtures in Zeolite
Cages
2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
347
Angewandte
Chemie
Nitrogen Heterocycles
M. C. Willis,* G. N. Brace,
I. P. Holmes
A single tandem operation allows rapid
access to a variety of substituted Nfunctionalized indoles. The nitrogen atom
of the indole nucleus is incorporated
through Pd-catalyzed aryl and alkenyl C N
403 – 406
Palladium-Catalyzed Tandem Alkenyl and
Aryl C N Bond Formation: A Cascade
N-Annulation Route to 1-Functionalized
Indoles
bond-forming reactions (see scheme;
dba = dibenzylideneacetone).
Amine, aniline, amide, carbamate, and
sulfonamide functional groups can be
introduced efficiently.
Synthetic Methods
M. Ochiai,* Y. Nishi, S. Goto,
H. J. Frohn
Symmetrical 1,3-diynes result from the
oxidative homocoupling reaction of alkynylstannanes with an aryldifluoro-l3-bromane in the presence of BF3·Et2O (see
scheme, Ar = p-CF3C6H4). The reaction
Plated gold: Self-assembly of core/shell
nanostructures occurs spontaneously
when gold nanoparticles are combined
with amphiphilic block copolymers. Polymer cross-linking then topologically fixes
the composite nanostructure (see picture). The thickness of the polymer shell,
as well as the optical and chemical
properties of the composite nanostructure, are precisely determined by the
involves a Michael addition of alkynylstannanes to the initially formed alkynyll3-bromanes. Cross-coupling of alkynyl-l3bromanes with alkynylstannanes affords
unsymmetrical 1,3-diynes (see scheme).
406 – 409
1-Alkynyl(aryl)(tetrafluoroborato)-l3-bromanes as Highly Efficient Michael Acceptors: Uncatalyzed Conjugate Addition of
1-Alkynyl(trialkyl)stannanes To Yield Symmetrical and Unsymmetrical 1,3-Butadiynes
Nanoparticles
Y. Kang, T. A. Taton*
409 – 412
Core/Shell Gold Nanoparticles by SelfAssembly and Crosslinking of Micellar,
Block-Copolymer Shells
molecular characteristics of the assembled block copolymer.
Asymmetric Catalysis
M. T. Reetz,* J.-A. Ma,
R. Goddard
Buried in the symmetry: Phosphorylation
of ortho-substituted binol derivatives
leads to monodentate phosphites
(X = OR) or phosphoramidites (X = NR2)
having stereogenic centers at phosphorus
Angew. Chem. Int. Ed. 2005, 43, 346 – 355
(see scheme). Such compounds are
excellent ligands in rhodium-catalyzed
olefin-hydrogenation (95–99 % ee) surpassing the C2-symmetric parent ligands.
www.angewandte.org
412 – 415
Binol-Derived Monodentate Phosphites
and Phosphoramidites with Phosphorus
Stereogenic Centers: Novel Ligands for
Transition-Metal Catalysis
2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
349
Contents
SAM Photochemistry
M. Abe,* T. Masuda, T. Kondo, K. Uosaki,*
Y. Sasaki*
416 – 419
Photoconversion of a Redox-Active SelfAssembled Monolayer: In Situ Probing of
Photoinduced CO Dissociation from a
Triruthenium Cluster Center on Gold
Drug Delivery
W.-D. Jang, N. Nishiyama, G.-D. Zhang,
A. Harada, D.-L. Jiang, S. Kawauchi,
Y. Morimoto, M. Kikuchi, H. Koyama,
T. Aida, K. Kataoka*
419 – 423
Supramolecular Nanocarrier of Anionic
Dendrimer Porphyrins with Cationic Block
Copolymers Modified with Polyethylene
Glycol to Enhance Intracellular Photodynamic Efficacy
NMR Spectroscopic Methods (1)
J. C. Freudenberger, S. Knr, K. Kobzar,
D. Heckmann, T. Paululat, H. Kessler,
B. Luy*
423 – 426
Stretched Poly(vinyl acetate) Gels as NMR
Alignment Media for the Measurement of
Residual Dipolar Couplings in Polar
Organic Solvents
NMR Spectroscopic Methods (2)
P. Haberz, J. Farjon,
C. Griesinger*
427 – 429
A DMSO-Compatible Orienting Medium:
Towards the Investigation of the Stereochemistry of Natural Products
350
Photoresponsive self-assembled monolayers (SAMs): Photoexcitation of a CObearing trinuclear ruthenium cluster
assembled on an Au(111) electrode
results in dissociation of CO to form a
H2O-terminated SAM (see picture). This
is the first well-defined example of clean
conversion of a redox-active molecular
film by using light stimulus.
Photo finish: A polymeric micelle system
is formed in aqueous media by electrostatic assembly of an anionic dendrimeric
porphyrin and a poly(ethylene glycol)–
poly(l-lysine) block copolymer (see picture). The micelles exhibit high photocytotoxicity and stability. The hydrodynamic
size (ca. 60 nm) makes this polymeric
micelle system suitable for intravenous
administration in photodynamic tumor
therapy.
Partial alignment of molecules in polar
organic solvents for the measurement of
residual dipolar couplings (RDCs) in highresolution NMR spectroscopy can be
achieved by stretched poly(vinyl acetate)
gels. The method opens the door of RDCderived structural information (e.g. from
DCH couplings, see picture) to new classes
of molecules by closing the existing gap
between apolar and aqueous solutions.
Organic molecules of different complexity
are aligned by a DMSO-compatible gel in
such a way that C–H dipolar couplings up
to 29 Hz are observed. This paves the way
to the simultaneous determination of
conformation and configuration of
organic compounds by NMR spectroscopy and thus enables the determination
of the stereochemistry of natural products
(e.g. hormaomycin, see picture) that
cannot be crystallized.
2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Angew. Chem. Int. Ed. 2005, 43, 346 – 355
Angewandte
Chemie
Catalytic emulsion polymerization with a
hydrophilic catalyst afforded extraordinarily small polyethylene particles of
< 20 nm size in the form of aqueous
dispersions. The small size of the particles
renders the dispersions transparent (see
picture).
Polymers
On the way: Chlorination of C60 with ICl or
VCl4 results in the formation of two novel
chlorofullerenes, C1-C60Cl28 and C2-C60Cl30,
respectively, which comprise two aromatic
rings and two chains of sp3-hybridized
carbon atoms that bear chlorine atoms
(the picture shows C60Cl30 ; Cl green).
These molecules are kinetically stable
intermediates on the way from C60Cl24 to
the thermodynamically stable D3d-C60Cl30.
Fullerenes
Reversible binding of dioxygen occurs in
aqueous solution to a myoglobin model
composed of a porphinato iron(ii) compound and a per-O-methylated b-cyclodextrin dimer with a pyridine linker (see
picture). The dioxygen affinity of this
system is 17.5 1.7 Torr and the half-life of
the O2 adduct is 30.1 h in phosphate
buffer at pH 7 and 25 8C.
Supramolecular Chemistry
L. Kolb, V. Monteil, R. Thomann,
S. Mecking*
429 – 432
Aqueous Dispersions of Extraordinarily
Small Polyethylene Nanoparticles
S. I. Troyanov,* N. B. Shustova,
A. A. Popov, L. N. Sidorov,
E. Kemnitz
432 – 435
Preparation and Structural Characterization of Two Kinetically Stable Chlorofullerenes, C60Cl28 and C60Cl30
K. Kano,* H. Kitagishi, M. Kodera,
S. Hirota
435 – 438
Dioxygen Binding to a Simple Myoglobin
Model in Aqueous Solution
Cooperativity between metal centers and
a bridging radical ligand, reflected by
ferromagnetic exchange coupling, was
studied with the dicopper complex shown.
The stability, and thus the reactivity of the
complex, is finely tuned by both the
nuclearity of the complex and the nature
of the coordinating solvent X.
Getting the right mix: Controlling the
extent of the charge on the surfaces of
carboxy-coated latex nanoparticles
enables ultrastable oil-in-water and waterin-oil emulsions to be prepared. Emulsion
inversion is simply achieved by changing
the pH value (see picture) or salt concentration.
Angew. Chem. Int. Ed. 2005, 43, 346 – 355
www.angewandte.org
Metal–Radical Complexes
F. Michel, S. Torelli, F. Thomas,* C. Duboc,
C. Philouze, C. Belle, S. Hamman,
E. Saint-Aman, J.-L. Pierre
438 – 441
An Unprecedented Bridging Phenoxyl
Radical in Dicopper(ii) Complexes:
3
Evidence for an S = 2 Spin State
Nanostructures
B. P. Binks,* J. A. Rodrigues
441 – 444
Inversion of Emulsions Stabilized Solely
by Ionizable Nanoparticles
2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
351
Contents
Carbene Ligands
A ferrocenyl–imidazolium salt can be
employed as a precursor to a stable
[IrIII(H)(biscarbene)] complex (see X-ray
crystal structure) under very mild conditions. The study shows that the role of the
base in the activation of the imidazolium
salt may not just be a simple deprotonation of the precursor.
M. Viciano, E. Mas-Marz, M. Poyatos,
M. Sanaffl, R. H. Crabtree,
E. Peris*
444 – 447
An N-Heterocyclic Carbene/Iridium
Hydride Complex from the Oxidative
Addition of a Ferrocenyl–Bisimidazolium
Salt: Implications for Synthesis
Aminoglycosides
M. Fridman, V. Belakhov, L. V. Lee,
F.-S. Liang, C.-H. Wong,*
T. Baasov*
447 – 452
Dual Effect of Synthetic Aminoglycosides:
Antibacterial Activity against Bacillus
anthracis and Inhibition of Anthrax Lethal
Factor
Fluorous-Phase Synthesis
L. A. McAllister, R. A. McCormick,
S. Brand, D. J. Procter*
452 – 455
A Fluorous-Phase Pummerer CyclativeCapture Strategy for the Synthesis of
Nitrogen Heterocycles
Defence against bioterrorism: Recent
events have created an urgent need for
therapeutic strategies to treat anthrax, an
infectious disease caused by the toxigenic
bacterium Bacillus anthracis. A new class
of aminoglycosides (see picture) are
powerful inhibitors under physiological
conditions of the anthrax lethal factor,
which has a major role in the disease, and
function simultaneously as antibiotics
against B. anthracis.
Catching on: Fluorous-tagged heterocyclic
frameworks accessed rapidly through a
Pummerer cyclative-capture approach can
then be modified conveniently, for example, by Pd-catalyzed cross-coupling. Traceless, reductive cleavage of the fluorous
phase tag completes a strategy for the
high-throughput, fluorous-phase synthesis of N heterocycles (see scheme,
RF = C8F17CH2CH2).
Homogeneous Catalysis
S. Ko, B. Kang, S. Chang*
455 – 457
Cooperative Catalysis by Ru and Pd for the
Direct Coupling of a Chelating Aldehyde
with Iodoarenes or Organostannanes
Two is better than one: The combination
of two metallic catalyst systems effects
transformations that are difficult to carry
out with any single-catalyst systems. This
is demonstrated by the coupling of 8-
352
2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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quinolinecarboxaldehyde with a range of
iodoarenes to give diaryl ketones (see
picture) and its reaction with organostannanes to afford ketones.
Angew. Chem. Int. Ed. 2005, 43, 346 – 355
Angewandte
Chemie
One stereogenic center suffices in
pyridinebis(oxazoline) (pybox) ligands for
efficient ruthenium-catalyzed cyclopropanation. A molecular-modeling study
reveals the main origin of the enantioselectivity to be unfavorable steric
interactions between the substituent on
pybox and styrene in a Si approach to the
carbene intermediate (see picture).
The missing link in the 28-electron family
of open-chain N4, N2CO, and C2O2 molecules has been detected in the gas phase
as an isolated, intact N2CO species,
whose lifetime exceeds 0.8 ms. The new
metastable molecule has been prepared
by neutralization–reionization mass
spectrometry of labeled N2CO+ ions,
which were generated in various N2/CO
ionized mixtures (see picture).
Molecular Modeling
A. Cornejo, J. M. Fraile, J. I. Garca,*
M. J. Gil, V. Martnez-Merino,
J. A. Mayoral, L. Salvatella
458 – 461
Asymmetric versus C2-Symmetric
Ligands: Origin of the Enantioselectivity
in Ruthenium–Pybox-Catalyzed Cyclopropanation Reactions
Metastable Molecules
G. de Petris,* F. Cacace, R. Cipollini,
A. Cartoni, M. Rosi, A. Troiani 462 – 465
Experimental Detection of Theoretically
Predicted N2CO
Asymmetric Catalysis
T. P. Yoon, E. N. Jacobsen*
466 – 468
Highly Enantioselective ThioureaCatalyzed Nitro-Mannich Reactions
Approaching “privileged” status? A new
and highly effective enantioselective catalyst for the nitro-Mannich reaction was
identified by modification of thiourea-
based Strecker catalysts (see scheme).
Products are obtained in high enantiomeric purity and up to 16:1 diastereoselectivity.
Homogeneous Catalysis
H. Kusama, H. Yamabe, Y. Onizawa,
T. Hoshino, N. Iwasawa*
468 – 470
Bicycle production: The low-valent rhenium complex [ReCl(CO)5] catalyzes a
tandem intramolecular cyclization reaction of w-acetylenic dienol silyl ethers. The
alkyne undergoes a geminal carbofunc-
Angew. Chem. Int. Ed. 2005, 43, 346 – 355
tionalization in the presence of 0.5–
3.0 mol % [ReCl(CO)5] under photoirradiation to give bicyclic enol silyl ethers in
high yields (see scheme, TIPS = triisopropylsilyl).
www.angewandte.org
Rhenium(i)-Catalyzed Intramolecular
Geminal Carbofunctionalization of Alkynes: Tandem Cyclization of w-Acetylenic
Dienol Silyl Ethers
2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
353
Contents
Bioorganic Chemistry
L. Krck, A. Heckel*
471 – 473
Photoinduced Transcription by Using
Temporarily Mismatched Caged
Oligonucleotides
Spatial and temporal control of the function of DNA with light: In oligonucleotides, protected (“caged”) thymidine can
act as a temporary mismatch in base
pairing and, for example, prevent transcription. The photolabile caging group
can be removed by light (see picture), fully
restoring an intact DNA strand.
Tin Complexes
F. Breher,* H. Regger
Alkene analogues: Simple acid–base
reactions of [Sn{N(SiMe3)2}2] with 3,5substituted pyrazoles, H(3,5-R2pz)
(R = CF3 and CMe3), give the homoleptic
tin(ii) pyrazolyl compounds, [{Sn(3,5R2pz)2}2]. Owing to additional N-donor
functionalities in the tin-bound ligand the
two stannylene entities dimerize in a
head-to-tail fashion (see structure) and
not through a covalent Sn Sn bond. Thus,
the title compounds can be described as
analogues of quadruply R-bridged
alkenes.
473 – 477
Distannenes Turned Inside Out: Bis(stannylenes) with an Unusual Structural
Motif
Dendritic Effects
Size does matter: Viologen dications
(blue) substituted with dendrons form
strong host–guest complexes with molecular tweezers (yellow) in solution and in
the gas phase (see picture). Complexation
even stabilizes dications which are intrinsically unstable as “naked” species in the
high vacuum of a mass spectrometer. A
remarkably pronounced effect of dendrimer size on the stability of these dications
switches their fragmentation between two
mechanisms.
C. A. Schalley,* C. Verhaelen, F.-G. Klrner,
U. Hahn, F. Vgtle
477 – 480
Gas-Phase Host–Guest Chemistry of
Dendritic Viologens and Molecular
Tweezers: A Remarkably Strong Effect on
Dication Stability
No way out: Small guest cations, such as
[Et4N]+ template the formation of stable
and tightly closed octaanionic metallosupramolecular tetrahedra (see picture).
Since [Et3NH]+ is co-encapsulated with
exactly one water molecule, the filling of
space seems to be a more pivotal factor
for the templation than the symmetry of
the cation. X-ray crystallography excellently agrees with NMR spectroscopy and
ESI-FT-ICR mass spectrometry data.
Cage Compounds
I. M. Mller,* D. Mller,
C. A. Schalley
480 – 484
Rational Design of Tightly Closed
Coordination Tetrahedra that are Stable in
the Solid State, in Solution, and in the Gas
Phase
354
2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Angew. Chem. Int. Ed. 2005, 43, 346 – 355
Angewandte
Chemie
Pulling power: The specific interaction of
individual (alkyl) ammonium residues
with a resorc[4]arene cavitand that is
attached to a gold surface are investigated. Measurements are made by attaching
the residue to the cantilever of an atomic
force microscope (AFM; see picture). The
results confirm that the affinity of the
guest for the host depends of their mutual
steric compatibility.
Single-Molecule Studies
R. Eckel, R. Ros, B. Decker, J. Mattay,*
D. Anselmetti*
484 – 488
Supramolecular Chemistry at the SingleMolecule Level
Service
Angew. Chem. Int. Ed. 2005, 43, 346 – 355
www.angewandte.org
Keywords
490
Authors
491
Preview
493
2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
355
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