вход по аккаунту


Graphical Abstract (Angew. Chem. Int. Ed. Engl. 13141995)

код для вставкиСкачать
i r IR
A Journal of the
Deutscher Chemiker
International Edition in English
Pages 1379- 1530
First the “Angewandte” fortnightly, and then on top of that
“Chemistry-A European Journal”-some
readers must have
thought: haven‘t they bitten off more than they can chew? Isn’t
it bound to go wrong? We indeed set ourselves an ambitious
goal. but we coped admirably. The best result, to be sure, is that
the doubling of the frequency of Angewandie Clienzie led to an
increase in subscriptions of 2.3% for the English edition and
6.2% for the German. The number of submitted communications climbed within one year by 25% (!) to 1005; in the first
half of 1995 again about 10% more than in the previous year
were received. The concern of some readers that with a twicemonthly publication frequency Angeivandtc, Cliemie would have
to accept manuscripts of inferior quality has long since evaporated. Although in 1994 we published 450 more pages (25% !)
than i n 1993. the rejection rate was unfortunately higher than
ever (48% i n 1994 and 54% i n the first quarter of 1995)- .-and
that in spite of the careful consideration authors give to the
choice of journal for their papers.
This year marks the twentieth anniversary of Angeirundtc,
C‘/zcmic~’sannotated Table of Contents. It has served as model
for almost all chemistry journals and is very much appreciated
by our readers. In this anniversary year we have introduced a
new service- keywords have been appended to each article and
are collated at the end of each issue.
So the signs of the times were read correctly. and the course
was set for further success. A. Binz (Editor-in-chief from 1922-
1932) formulated the goal of Angewundte Chcvnie as follows:
“Angeivandte Cheiizie aims to reflect the best achievements of
chemical science.” This aim has not changed i n spite of the ever
increasing number of readers and authors.
It is less than a year ago that Clzeniistry- A European Journul
was announced and the first papers arrived in the editorial
office in late fall of 1994. Feedback from authors both in
Europe and in the rest of the world was extremely positive from
the start. The number and quality of the manuscripts have exceeded all the optimistic expections. In order to improve
manuscript throughput rapidly in response to increasing submissions, the ”Chemistry” team was expanded to include an
editorial assistant on July 1. 1995. In 1995 we will offer 600-700
pages of full papers, without asking subscribers for a penny
more. Clwmistry -A European Journal will stay with Angewandie Clzcwzie in 1996, and for the projected 1500 extra pages
a surcharge will be added to the subscription rate. Publication
together with Angewundte Cliernie ensures the highest possible
distribution. When Chemistry finally goes its own way in 1997,
every reader and librarian will have enough experience with the
new journal to decide whether to subscribe. Please take note
yourself or remind your librarian that Cherriistr! should be
bound separately in 1995 as Volume 1 (Clzenz. Eur. J: 1995, f);
the pagination is entirely independent of that of Angettandie
The cover picture shows the bowl-shaped structure of the highly strained tricycle.
dilithium acepentalenediide (C atoms blue-gray, H atoms white). Accordingly, the
as yet unknown neutral hydrocarbon, acepentalene, should also have a bowl-shaped
structure. In the solid state the dilithium acepentalenediide forms dimeric contact
ion triplets, in which the convex side of the two dianion fragments point towards
each other; the lithium counterions (silver) are coordinatively saturated with
dimethoxyethane ligands (0 atoms red). The computer graphics were generated by
Dr. H. Michaelsen with a “ray tracing” program (Persistence of Vision 2.2) on a
Power Challenge L (Silicon Graphics). More about this unusual dianion is reported
by A. de Meijere. D. Stalke et al. on page 1492ff.
From the Organic Chemistry Institute of the Technical University of Budapest via the
laboratories of the Dow Chemical Company (in Canada and the USA) and the Case
Western Reserve University (Cleveland, Ohio), the path of George A. Olah finally
led to the University of California in Los Angeles. At all research stations he pursued
his major interest in carbocations, whose existence was still questioned by many at
the beginning of his career. Olah gave the cations of carbon longer life to allow their
observation in superacidic medium, and made the distinction between carbenium and
carbonium ions. The reminiscences on an exciting bit of chemical history and a
glimpse into his actual research make Olah’s Nobel Lecture a must for every chemist.
G . A. Olah * ...........................
How is the hormone-activated synthesis of the second messenger cyclic AMP regulated? Or, in more general terms, how does the interaction of an extracellular agonist
with a receptor lead to intracellular enzyme activity when receptor and enzyme are
not distinct macromolecules? The mediators are membrane-bound, guanine nucleotide binding regulatory proteins (G proteins). When the receptor is activated,
G proteins dissociate into their subunits. These in turn activate or inhibit enzymes
such as adenylate cyclases, which catalyze the synthesis of cyclic AMP. In these
signal transmission processes G proteins act as molecular switches and amplifiers.
A. G . Gilman* ......................
Biological communication requires a complex meshwork of guanine nucleotide binding proteins ( G proteins), receptors, effectors, and structure-forming extra- and
intracellular components of cell membranes. The starting point for the development
of the theory of cellular signal transduction was a very simple model (see scheme
below). When a hormone H activates a receptor, a transducer (a G protein multimer) triggers the release of an enzyme as an intracellular reply.
M . Rodbell * ..........................
1393 - 1405
My Search for Carbocations and Their Role
in Chemistry (Nobel Lecture)
G Proteins and Regulation of Adenylate
Cyclase (Nobel Lecture)
1420- 1428
Signal Transduction : Evolution of an Idea
(Nobel Lecture)
Fullerene fragments and other fullerene model compounds not only mimic certain aspects of the carbon
spheres, but they are also fascinating
compounds in their own right. Novel
annelated polycyclic arenes such as 1
have been synthesized, whose anions
could potentially form endo- and
exohedral complexes with metal cations. Recently the hydrocarbon cage
R . Faust* ..............................
Fullerene Model Compounds :
Bowl-Shaped Aromatic Hydrocarbons
and Cyclophane-Based Cage Molecules
compound 2 ((&H6”) was found to
complex Ag’ ions selectively.
VCH Verlrrys~~..cell.~chuft
mhH, D-69451 Weinheirn, i Y Y 5
0570-0833/95~1313-1382S /0.00+ .2S/O
Angew. Chem. h i . Ed Engl.
1995,34, No. i3!14
Two monosaccharide building blocks, two reagents, and four steps are all it takes to
synthcske heptasaccharide 1 according to a new strategy by T. Ogawa et al. In view
of the tremendous arsenal of glycosylation reactions. this new method should inspire
other related approaches.
H. Padsen* ...........................
Progress in Oligosaccharide Synthesis
through a New, Orthogonal Glycosylation
0 ~ "
0 ~ "
A strong n acceptor and a strong n donor-NO and
0 ligands, respectively -coordinated cis to the
same metal atom are present in the complex 1. The
NO stretching frequency of the linear W-NO
unit occurs at extremely low wavenumber
(1 433 cm ' ) . The red complex 1 forms by reduction
of [WL(CO)z(NO)]cto [WL(NO)(CO)(Me)] (L =
heterocycle) followed by reaction with 0 2 .
J. Bohmer. K. Wieghardt.*
B. Nuber .................................
[WL(NO)(O)(CH,)]--An Unusual
Nitrosyltungsten Complex
H. Meier,* K . Miiller ........_._.1437-1439
The photocyclodimerization of areno-condensed
(18lannulenes with alkoxy side chains leads to novel
beltlike cyclophanes (schematic representation on
the right). For derivatives with certain substitution
patterns the "monomers" form columnar, photoreactive liquid crystals.
Synthesis of Belt Cyclophanes
Since the first synthesis of a silacyclopropene, efforts have been made to prepare the
unsubstituted parent compound 3. This goal has finally been achieved: Pyrolytic
elimination of trimethylsilane from 1 initially leads to the silanediyl2, which cyclizes
to 3.
SI \
G. Maier,* H. Pacl,
H. P. Reisenauer _........_..___.....
Silacyclopropene: Generation by HighVacuum Flash Pyrolysis and MatrixSpectroscopic Identification
/(A, H
Through interactions between sulfonic groups of the
water-soluble Au cluster C and imino groups of a
poly(ethyleni1nine) layer B on a mica surface A, this
cluster could be attached for the first time in a largely ordered form as a monolayer. Now, for example,
electronic transitions of quantum dots (cluster
cores) separated by ligand shells can be investigated.
n-Stacking interactions between adjacent aromatic
ligand fragments of L- separated by approximately
3.4 A provides a pathway for weak ferromagnetic
(1). The
coupling in the tetramer [Mn,L,](PF,),
cavity of L- is too large for a single Mn" ion; instead the tetramer 1 comprises a Mn, tetrahedron,
with a ligund L- attached to each triangular face. In
the self-assembly of 1 , eight components are combined under the formation of 24 M n - N bonds to
give a complicated structure.
S. Peschel, G. Schmid* _.___.....
1442- 1443
First Steps Towards Ordered Monolayers
of Ligand-Stabilized Gold Clusters
A. J. Amoroso, J. C. Jeffery. P. L. Jones,
J. A. McCleverty,* P. Thornton,
M. D. Ward* ...._____.........._.....
Self-Assembly of a Ferromagnetically
Coupled Manganese(ii) Tetramer
Cyclic tetrameric units (*.Mn-NC-Fe-CN*.),(depicted on the right) construct the two-dimensional
network of the title compound. The layers thus
formed are linked together by van der Waals cont x t s . The compound displays metamagnetisin : ferromagnetic coupling is observed within layers and
antiferromagnetic coupling between layers.
H. Miyasaka, N. Matsumoto,*
H. Okawa, N. Re, E. Gallo,
C. Floriani* ...........................
The Two-Dimensional Network Structure
and Metamagnetic Properties of the 2 : l
Complex of [Mn(3-MeOsalen)(H2O)]C1O~
and K,[Fe(CN),]
Preorganization by intramolecularhydrogen bonds facilitates the synthesis of macrobicyclic Ti'" complexes with ring sizes up to 32 atoms (shown schematically below).
C,-symmetric peptide bundles, each fixed by a central nitrogen atom, serve as
ligands. AS = a-amino acids (Gly, Leu, Phe, Val).
K . Severin, W. Beck,* G. Trojandt,
K. Polborn, W. Steglich* ....... 1449-1451
Macrobicyclic Titanium(rv) Complexes
with C,-Symmetric Synthetic Peptides
Despite the absence of water channels, H / D and H,160/H,'80 exchange experiments
show that water molecules diffuse rapidly through the crystal lattice of [I-cyclodextrin' 12H,O (CD). Exchange takes place in minutes and follows first-order kinetics.
This is explained by the structural fluctuations of the b-CD molecules, which became
apparent in crystallographic studies and in computer simulations.
T. Steiner, A. M. Moreira da Silva,
J. J. C. Teixeira-Dias, J. Muller.
W. Saenger* ...........................
Cyclohexatriene lost, cyclohexatriene regained! Recently the Mills -Nixon postulate concerning the
structure of benzene derivatives was recognized to
be invalid. A new view on strain-induced bond localization in benzene led to the design and synthesis of
tris(bicyclo[2.1 .l]hexenojbenzene (1j , which shows
significant distortion toward a cyclohexatriene geometry.
H.-B. Biirgi,* K. K. Baldridge,
K. Hardcastle, N. L. Frank. P. Gantzel,
J. S. Siegel,* J. Ziller ............... 1454-1456
Rapid Water Diffusion in a Cage-Type
Crystal Lattice : p-Cyclodextrin Dodecahydrate
X-Ray Diffraction Evidence for a Cyclohexatriene Motif in the Molecular Structure
of Tris(bicyclo[?.l .I]hexeno)benzene: Bond
Alternation after the Refutation of the
Mills-Nixon Theory
C. J. Hawker* ........................
The use of multifunctional initiators
such as 1 in a novel "living" free radical polymerization process allows
the preparation of low polydispersity
star and graft copolymers with accurate control over the molecular
weight of each arm.
Architectural Control in "Living" Free
Radical Polymerizations: Preparation of
Star and Graft Polymers
Novel, polymeric linear chains of Keggin polyoxometalate units PMnW, ,O,, linked
through Mn-0-W bridges (see picture below) are present in the structure of the
title compound 1. The chains alternate with layers of the organic donor bis(ethy1enedithio)tetrathiafulvalene (ET). Compound 1 promises interesting material properties resulting from the combination of localized magnetic moments with delocalized
J. R. Galhi-Mascaros, C. Gimenez-Saiz,
S. Triki, C. J. Gomez-Garcia,
E. Coronado.* L. Ouahab ..... 1460-1462
A Novel Chainlike Heteropolyanion
Formed by Keggin Units:
Synthesis and Structure of
,O,,l, . 2f?H,O
C. Hlussermann.
R. Nesper" ...............................
Planar-coordinated silicon atoms dominate the new
one-dimensional Zintl anion [Si!'-] that occurs in
the ternary compound Ba,Eu,Si,. Although the anion is isoelectronic with E:- (E = P. As), it has a
completely different structure (depicted here),
which most likely depends on the cation environment.
1462- 1464
A Silicon Strand of More than 7 A in
Diameter in Ba,Eu,Si,
Not the a-amino group but the 5-position of the imidazole ring functions as ii nucleophile towards the prosthetic dehydroalanine residue in the deamination of histidine
catalyzed by histidine ammonia lyase (HAL) [Eq. (a)]. The results discussed here
strongly support this proposal.
- f=Wooe
M. Langer. A. Pauling,
J. Rktey* ................................
1464- 1465
The Role of Dehydroalanine in Catalysis by
Histidine Ammonia Lyase
HN: ,+N
Cyclic fullerene- acetylene hybrids. a tris(ful1erene)( I t/o-C,
(1) dnd d tetrdkis(fullerene)-( I c/o-c,,
compound (2), were synthesized by Eglinton Glaser coupling Both oltgomers fragment under
MALDI-TOF MS conditions to give sequential loss
of the C , , units. which potentially provides controlled acces\ to the hitherto unknown free totis ( 1 (lo-C,, m d ( \(/o-CZ+,
X = (EtO,CCH,O,C),C
L Isadcs, P Seller,
F Diederich*
1466- 1469
Solubilized Derivatives ol C,,, dnd C,,,
The First Members of d New Class of
Carbon Allotropes C,,,,,,
1, n = 3
2, n = 4
D. Hamprecht, K. Polborn,
W. Steglich* . _ _ _ . _ _ _ _ _ _ _ . _1469-1471
Highly volatile and unstable in the pure form, the
2H-azepine 1 has been synthesized for the first time.
This compound is a "spin-off' from work on the
chemistry of azepine alkaloids. which occur in the
mushroom C'hrr1ripor.u.r piperatus. In addition. a bicyclic product of a surprising Diels-Alder reaction
forms in the cyclization step.
Extremely stiff macromolecules in the form of "hairy rods" or more precisely
"molecular bottlebrushes" (without a handle) are easily accessible by the polymerization of polymacromonomers. As anticipated from their high degree of stiffness.
these molecules form lyotropic, liquid-crystalline phases, although they consist of
"commodity" monomers like styrene and methylacrylate.
First Synthesis of 2H-Azepine
M. Wintermantel, K . Fischer.
M. Gerle, R. Ries, M. Schmidt.*
K. Kajiwara. H. Urakawa.
I. Watdoka .............................
1472- 1474
Lyotropic Phases Formed by
"Molecular Bottlebrushes"
High activities and selectivities are obtained for the rhodium-catalyzed hydrofonnylation of methyl acrylate in biphasic and "supported aqueous phase" (SAP)
systems [Eq. (a)]. The biphasic system Rh/P(C,H,SO,Na), 1 is twice as active
as the classic Rh/PPh, combination (homogeneous system). and the SAP system
Rh/P(C,H,S0,Na),/Si02 2 is twenty times inore active.
95 %
a / p > 120
G. Fremy, E. Monflier, J.-F. Carpentier,
Y. Castanet, A. Mortreux" .... 1474-1476
Enhancement of Catalytic Activity for
Hydroformylation of Methyl Acrylate by
Using Biphasic and "Supported Aqueous
Phase" Systems
The kinetics and thermodynamics of the electrocyclization of vinylallenes are favorably influenced when a silyl substituent is introduced into the open-chain compound. A series of vinylallenes containing a silyl group at the vinyl terminus (1) gave
good yields of the corresponding cyclobutenes 2 when heated at reflux in xylene. A
theoretical explanation for this observation remains elusive.
M . Murakami,* H. Amii,
K. Itami, Y. Ito* ....................
A Remarkable Effect of Silyl Substitution
on Electrocyclization of Vinylallenes
In four steps and a yield of 14%, the
[7]phenylene 1 has been prepared
from hexakis(trimethylsilylethynyl)benzene. The trigonal I is not planar
but slightly curved, and the unit cell
features two molecules, staggered
and offset, facing each other in a
concave -concave arrangement.
R. Boese,* A. J. Matzger, D. L. Mohler,
K. P. C. Vollhardt* ................ 1478-1481
C,-Symmetric Hexakis(trimethylsilyl)~7]phenylene ["Tris(biphenylenocyclobutadieno)cyclohexatriene"], a Polycyclic Benzenoid Hydrocarbon with Slightly Curved
Picosecond laser-flash photolysis is employed to
study intramolecular electron transfer and spinstate interconversion in a valence tautomeric cobalt
complex. The Co"' form 1 of the complex
is photoexcited to the high-spin Co"(semiquinone
low-spin form,
whereupon relaxation
back to the
0 0
state is monitored.
D. M. Adams. B. Li, J. D. Simon,*
D . N. Hendrickson* ...._._..._...
1481 -1483
Photoinduced Valence Tautomerism in
Cobalt Complexes Containing Semiquinone Anion as Ligand: Dynamics of the
High-Spin [Coii(3.5-dtbsq),] to Low-Spin
[Co"'(3,5-dtbsq)(3,5-dtbcat)] Interconversion
The introduction of alanine methyl groups in adjacent positions on a peptide ligand
results in a cooperative enhancement of electrostatic binding from the burial of
hydrocarbon. This observation may explain why larger changes in free energy occur
when hydrocarbon substituents are buried in a molecular recognition site than can
be accounted for by the solvent transfer model (classical hydrophobic effect).
G . J. Sharman, M. S. Searle,
B. Benhamu, P. Groves,
D. H. Williams* ....................
Consecutive Suzuki coupling provides a general method for preparing 1,8-diarylnaphthalenes such as 2 (A = acceptor, D = donor) from the boronic acid 1. Noncovalent K - K interactions render them markedly more NLO-active than the 1.5-isomers (which absorb at longer wavelength) and thus fascinating alternatives to the
best, classical, blue-transparent frequency doublers.
A. Bahl, W. Grahn,* S. Stadler, F. Feiner,
G . Bourhill, C. Brluchle, A. Reisner,
P. G . Jones .............._.__.____.____
Burial of Hydrocarbon Causes Cooperative
Enhancement of Electrostatic Binding
Novel, Blue-Transparent Frequency
Doublers Based on I&Di(hetero)arylnaphthalenes
A novel homobinuclear Cu, complex describes best the Cu, center of the cytochromec oxidase from bovine heart mitochondria according to EXAFS investigations. In
this complex, which contains two terminal histidine residues, two cysteine sulfur
bridges, and probably a bridging oxygen donor function, the Cu-Cu distance of
2.46 A is very short. The structure of the Fez,-Cu, center was likewise determined.
G. Henkel,* A. Miiller, S. Weissgriiber,
G. Buse, T. Soulimane, G. C. M. Steffens,
H.-F. Nolting .........................
The Active Sites of the Native Cytochromec Oxidase from Bovine Heart Mitochondria: EXAFS-Spectroscopic Characterization of a Novel Homobinuclear Copper
Center (Cu,) and of the Heterobinuclear
Fe,,-Cu, Center
VCH Ver/~,~sge.,P//.\~hqfl
m b H , 1)-69451 Wwdiein?, 1995
0570-0833,'95~/313-13863 /O.OO+ ,2510
Angrbv. Chem. Inr. Ed. Ennyl. 1995. 34. No. 13/14
Pure 4,7-bis(trimethylstannyl)dihydroacepentalene 1 can be transformed
cleanly into dilithium acepentalenediide
2 by treatinent with methyllithium. In
the crystal 2 adopts an interesting dimeric structure in which the convex sides of
the t w o bowl-shaped dianionic fragments face each other.
R. Haag, R. Fleischer, D. Stalke.*
A. de Meijere * . ..... . .._.. . . .. . . . . ... 1492 - 1495
R = SnMe,
\ ‘; I /
Dilithium Acepentalenediide: An Unusual
Dimer of Contact Ion Triplets with BowlShaped Dianions
Transition states for electron transfer with strong bonding interactions are reported in
the reactions of anion radicals 1 ( n = 2, 3). The heights of the activation barriers for
the substitution and electron transfer pathways leading to 2 and 3, respectively, are
a function of the length n of the methylene chain. This is predicted on the basis of
orbital selection rules derived from valence bond configuration mixing analysis, and
confirmed here by ab initio calculations.
G . N. Sastry, A. C. Reddy.
S. Shaik * .................................
Electron Transfer and Polar Reactions of
Cyclizable Anion Radicals: Structural
Consequences of Orbital Selection Rules
and Chain-Length Constraints
High structural regularity, second-order nonlinear
susceptibility, and thermal stability characterize the
self-assembled stilbazolium chromophoric multilayers (the structure obtained after the first cycle is
shown schematically on the right). A topotactic approach for the stilbazolium chromophore deposition has resulted in conceptually attractive, artificial, acentric assemblies for organic second-order
nonlinear materials.
W. Lin, S. Yitzchaik, W. Lin, A. Malik,
M. K. Durbin, A. G . Richter, G. K. Wong.
P. Dutta. T. J. Marks* ........... 1497-1499
Hexagonal and lamellar aluminosilicate mesostructures with a SiiAl ratio close to 1
have been obtained by a new two-step synthetic route. The precursor aluminosilicate
AI,Si,O, ,(OH): and the surfactants organize into mesophasic precipitates when
the corresponding solutions are mixed together. Further condensation and structure
ordering of the precipitated phases can then be achieved by vapor-phase treatment
or refluxing isopropyl alcohol treatment leading to mesostructural materials.
G. Fu, C. A. Fyfe,* W. Schwieger,
G . T. Kokotailo .....................
New Nonlinear Optical Materials :
Expedient Topotactic Self-Assembly of
Acentric Chromophoric Superlattices
Ketyl intermediates in unusual enzymatic reactions in
anaerobic bacteria may possibly be generated by
one-electron reductions of thioesters (coenzyme-A
esters). One example is the reversible syn-dehydra- CoAS
tion of (R)-2-hydroxyglutaryl-CoA via 1 to give ( E ) . Fe-S..-s
l ....,..
glutacon yl-Co A.
A sulfur atom is the smallest bridging element yet
incorporated into a [l]ferrocenophane. This is
demonstrated by the synthesis of the purple, crystalline [l]ferrocenophane 1 (structure depicted on
the right). The 31.05(10)‘ tilt angle between the
planes of the cyclopentadienyl rings is the largest for
any iron group [n]metallocenophane.
Structure Organization of Aluminosilicate
Polyanions with Surfactants: Optimization
of Al Incorporation in Aluminosilicate
Mesostructural Materials
W. Buckel,* R. Keese . _ _..._. . ... 1 502 - 1506
One-Electron Redox Reactions of CoASH
Esters in Anaerobic Bacteria A Mechanistic Proposal
J. K . Pudelski, D. P. Gates. R. Rulkens,
A. J. Lough, I. Manners* ...... 1506-1508
Synthesis and Structure of the First SulfurBridged [IIFerrocenophane
D. M. Poojary, D. Grohol,
A. Clearfield * ........................
Stacking interactions between phenyl
groups hold the unidimensional
channels in the structure of 1 together (shown on the right). The structure was determined from X-ray
powder diffraction data. which revealed that the channel opening is
more than 1 2 A and the free space
approximately 7 8, in diameter.
Synthesis and X-Ray Powder Structure of a
Novel Porous Uranyl Phenylphosphonate
Containing Unidimensional Channels
Flanked by Hydrophobic Regions
Extremely mild conditions suffice for the ZrC1,mediated rearrangement of permethylated arenes at
room temperature in halogenated solvents. This reaction. better known as the Jacobsen reaction, was
previously observed only in concentrated sulfuric
acid. In the presence of durene, (ZrC14)nis surprisingly soluble. The active species in the reaction of
C,Me, is shown on the right.
q'(N')- and q2(N',O6)-coordination of the Rh atoms by 9-ethylhypoxanthin (9-EH) is evident in the
cyclic trimer 1 (see picture). This is
formed from [(C,Me,RhCI,),],
AgOSO,CF,, and 9-EH in water at
pH 6.1. An entirely different coordination arises at pH 10.2 for the
complex with the ligand 9-methylhypoxanthin (9-MH): in the dimer
2 the metal atoms are q'(N')-coordinated. The formation of dramatically different structures a t various
pH values could be explained by
the changes in the nucleophilicity
of the N7, 06, and N1 binding
Hydrocarbon Activation with Metal
Halides: Catalysis of the Jacobsen Rearrangement by (ZrCI4)" in the Presence of
Aromatic Hydrocarbons
A new pentadentate nitrogen ligand facilitates the
synthesis of a low-spin iron(rr) complex, which reacts with H,O, at low temperature to form the transient purple complex 1. Complex 1 was formulated
as an Fe'"0OH complex, the first synthetic example
of such a species to be characterized by electrospray
ionization mass spectrometry. Furthermore. 1 oxidizes cyclohexane efficiently, thus supporting the
notion that an Fe"'0OH moiety can participate in
oxygen activation mechanisms of nonheme iron enzymes.
E. Solari, F. Musso, R. Ferguson,
C. Floriani,* A. Chiesi-Villa,
C. Rizzoli ...............................
M. Lubben, A. Meetsma, E. C. Wilkinson.
B. Feringa, L. Que, Jr.* ......... 1512-1514
Iron Centers in Oxygen Activa,$:&~ Nonheme
tion: Characterization of an Iron(n1)
Hydroperoxide Intermediate
H. Chen, M. M. Olmstead,
D. P. Smith, M . F. Maestre.
R. H. Fish* ............................
The pH-Dependent Synthesis and Structural Study of Dimeric and Cyclic Trimeric
Complexes of 9-Methyl- or 9-Ethylhypoxanthine Nucleobases with ($-Pentamethylcyclopentadieny1)rhodium Aqua Complexes
Do intramolecular Li-F interactions affect the reactivity of aryne precursors‘?This
was the key question for structural studies of lithiated and nonlithiated tetrafluorobenzene. N o correlation between Li-F distances and the ease of LiF elimination
exists. and the lengths of the Car,,-F bonds in the lithiated compound are less
affected by Li - F interactions than by the “anionic” character of the benzene ring.
T. Kottke, K. Sung,
R. J. Lagow’ .........................
Single-Crystal X-Ray Structure of the
Metastable Aryne Precursor Tetrafluorophenyllithium and of 12.3.4-Tetrafluorobenzene
* Author
to w h o m corrrspondencc \liould he addrtssed
Modern Electroorganic Chemistry
. Z . A. Shabarova, A. A. Bogdanov
C. Meicr ..........................................
K . Sc(firt .........................................
. G. Tdlksy
H . M . Heist .....................................
C. H. Wong, G. M . Whitesides
H . Schick .........................................
Advanced Organic Chemistry of Nucleic Acids
. D. Kyriacou
Derivative Spectrophotometry. Low and High Order
Enzymes in Synthetic Organic Chemistry
Keyword Index 1526
Author Index 1527
Chemistry-A European Journal may be found after page
1528 with its own table of contents and separate pagination.
The following reviews will appear in future issues:
Computer-Assisted Planning of Organic Chemical Synthesis: The Second Generation
.I.Gasteiger and W-D. Thlenfeldt
Electronegativity and Molecular Properties
J. Hinze and D. Bergmann
Scalar Coupling: Its Analysis and Application in the Elucidation of Structure
H. Kessler et al.
Cytomimetic Organic Chemistry: Early Developments
F. M. Menger and K. D. Gabrielson
Supramolecular Inorganic Chemistry : Guests in Small and Large Hosts
A. Miiller et al.
Synthetic Aspects of Metal-Catalyzed Oxidations of Amines and Related Reactions
S.- I. M ura ha sh i
Chemistry of Inositol Lipid Mediated Cellular Signaling
B. V. L. Potter and D. Lainpe
C-H and C-c‘ Bond Activation by “Bare” Transition-Metal Oxide Cations in the Gas Phase
H . Schwarz and D. Schroder
Molecular Iinprinting in Cross-Linked Materials with the Aid of Template Molecules
G. Wulff
Supramolecular Synthons in Crystal Engineering-The
G . R. Desiraju
New Organic Synthesis
The Schenck Ene Reaction: Diastereoselective Oxyfunctionalization with Singlet Oxygen in Synthetic Applications
W. Adam
L. Weber
Exotics to Versatile Building Blocks in Preparative Chemistry
Preview 1528
Без категории
Размер файла
733 Кб
abstract, int, angel, engl, 13141995, chem, graphical
Пожаловаться на содержимое документа