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Graphical Abstract (Angew. Chem. Int. Ed. Engl. 211994)

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of the
Gesellschaft
Deutscher Chemiker
1994
International Edition in English
33/21
Pages 2121 -2228
COVER PICTURE
The cover picture shows probably the most densely oxygenated complex fragment of
! The central triol-triacid “core”
a natural product yet synthesized-C,,H,,O,
(space-filling model at the top) of the fungal metabolite zaragozic acid A/squalestatin S1 (structural formula and space-filling model at the bottom) is depicted. Showing
unprecedented promise as a medicinally useful inhibitor of squalene synthase (the
enzyme controlling the first committed step in the biosynthesis of cholesterol),
zaragozic acid A has attracted much attention in biological and chemical circles. The
synthesis of the central core and the first total synthesis of zaragozic acid A/
squalestatin S1- -another race is over are described by K. C. Nicolaou et al. on p.
2184ff, 1187ff.. and 2190ff. (Red: oxygen. black: carbon, white: hydrogen; photograph: L. Gomez-Paloma, The Scripps Research Institute.)
REVIEWS
Contents
Not exactly easy to describe are electron transfer (ET) reactions in which both the
oxidized and the reduced form of a compound are present simultaneously; only one
electron is transferred. and no chemical bonds are broken or formed during the
reaction. What powerful models are available for such “simple” reactions? Which
experimental methods can be used, in particular for the very fast ET reactions? What
influence do the solvent, reactant. and double layer exert on the thermodynamic and
kinetic parameters? Critical answers are provided by Fawcett and Opallo in this
review.
W. R. Fawcett.*
M. Opallo ..............................
Despite wartime hardships research was still well documented. This article on Otto
Roelen and the discovery and development of the 0 x 0 synthesis [Eq. (a)] describes
the infancy of industrial homogeneous catalysis with organometallic complexes. The
authors try to understand why a collaboration between the industrial chemist Otto
Roelen and Professor Walter Hieber never came to be. If they had combined efforts,
the 0x0 synthesis might have been recognized much earlier as a homogeneously
catalyzed reaction.
B. Cornils,*
W. A. Herrmann,
M. Rasch ....._....__.
. _ _ _ _ . . . . _ _ .2144-21
_ . _ _ _ . 63
RCH=CI1
+ CO + H z
‘HCo‘Co)4’
I
RCH,CH,CHO
(a)
21 31 -2143
The Kinetics of Heterogeneous Electron
Transfer Reactions in Polar Solvents
Otto Roelen, Pioneer in Industrial Homogeneous Catalysis
HIGHLIGHTS
Contents
Less conventional oxidation states of the lanthanoids
become important in complexes in which ligands
such as trimethylsilyl-substituted cyclooctatetraene
anions or imidazol-2-ylidenes coordinate to the
metal ion. These types of Ln"' complexes (n ?= 3 ) .
which were still ignored ten years ago, may have
sandwich o r even oligodecker structures (see, for
example, picture on the right) or contain carbenelike q'-bound ligands.
Me,Si
SiMe,
lll,,,.
p
Me,Si
,,,,SiMe,
Ce
Me,Si
Me,Si
9
"
SiMe,
Yb
A S i M e ,
R. D. Fischer* .......................
2165-2168
New Upswing of Organolanthanoid Research: A Very Promising Revival of
Organocerium(1v) Chemistry and the First
Stable Lanthanoid(Ir/III)-Carbene Complexes
Me3Si
Me3Si
The resurgence of the C, ligand in main group chemistry: Recently Harder et al. (Angew. Ckem. Int. Ed.
Engl. 1994, 33. 1744) have synthesized and structurally characterized the lithocene anion 1, the simplest sandwich complex, and Hanusa et al. (Angew.
Clwrn. Int. Ed. Engl. 1994, 33. 2191) have prepared
the "open" calcocene 2, an alkaline-earth metal
complex with a remarkable structure. Such compounds are not only of significance for bonding theory, they are also interesting as precursors for important Industrial processes.
D. Stalke* .............................
2168-2171
The Lithocene Anion and "Open" Calcocene~ New Impulses in the Chemistry of
Alkali and Alkaline Earth Metallocenes
2
1
COMMUNICATIONS
Isolated fibers the thickness of a molecule
but more than lo4 molecules long are
present in the gel formed from a solution
of 1 in chloroform. This molecular stack
may be seen as a molecular cable containing many wires and constructed from a
stack of phthalocyanine units, four stacks
of crown ether units, and a surrounding
mantel of hydrocarbon chains.
A shift of up to 9 ppm in the 19FN M R resonance of
1 is observed on complexation of metal ions. This
property makes these compounds attractive as sensors for metal ions. The mode of coordination ( o
bonding to the fluorine atom or q2 coordination to
the C - F bond) in this type of system is also of
interest.
Lo
C. F. van Nostrum,
S. J. Picken,
R. J. M. Nolte* ...............
21 73-21 75
OJ
Construction of a Multiwired Molecular
Cable of Micrometer Length by a SelfAssembly Process
C"
0 2
t o
"I
H. Plenio,*
R. Diodone ............................
C02
@+
1, n = 1-3
C02
Y-03
The highly convergent and versatile synthesis of the GPI anchor 1 is based on the
assembly of four building blocks, which are obtained in high yields from readily
accessible starting materials.
2175-2177
Complexes of Partially Fluorinated Macrocycles with a Metal-Fluorine o-Donor
Bond and Their Suitability as Metal Ion
Indicators
T. G. Mayer, B. Kratzer,
R. R. Schmidt* ......................
2177-2281
Synthesis of a GPI Anchor of Yeast (Scrccharonqws cerevisiue)
B. M. Trost,*
P. D. Greenspan, H. Geissler,
J. H. Kim. N. Greeves ............ 2182-2184
Three palladium-catalyzed steps (ally1 alkylation,
pling) characterize
Wacker
oxidation,theand
firstcarbonylative
asymmetric total
cross-cousynthe-
&OH
sis of 1. a component of plant extracts used as contraceptives.
0
Hoe..
.
c H3
1, R = (CH&C=CHCHz
zoapatanol
Step by step the first total synthesis was approached: of the zaragozic acids/
squalestatins showing potential therapeutic value for lowering the serum cholesterol
concentration. zaragozic acid A/squalestatin S1 ( l ) , the most abundant member of
a new class of naturally occurring products, has now been synthesized via the key
intermediates 2 and 3. Initially the projected final sequence (2 -1) was achieved, and
the side chains attached to C 1 and C 6 were prepared through efficient asymmetric
syntheses. The first synthesis of the highly oxygenated “core”, which is characteristic
of this class of natural products, was achieved from a simple prochiral diene via
intermediate 3. Finally the synthetic route 3 2 was developed to successfully complete the total synthesis. Bn = benzyl, PMB = para-methoxybenzyl, TMS = trimethylsilyl.
-
A Total Synthesis of (+)-2’S,3‘R-Zoapatanol
K. C. Nicolaou,*
E. W. Yue, Y. Naniwa,
F. De Riccardis, A. Nadin,
J. E. Leresche,
S. La Greca, Z. Yang ............. 2184-2187
Zaragozic Acid A/Squalestatin S1: Synthetic and Retrosynthetic Studies
K. C. Nicolaou,* A. Nadin,
J. E. Leresche, S. La Greca, T. Tsuri,
E. W. Yue, Z. Yang ................ 2187-2190
n
Synthesis of the First Fully Functionalized
Core of the Zaragozic Acids/Squalestatins
K. C. Nicolaou.* A. Nadin,
J. E. Leresche, E. W. Yue,
S. La Greca ............................
2190-2191
Total Synthesis of Zaragozic Acid
A/Squalestatin S1
J. S. Overby,
Calcium behaves more like a transition metal than
a main-group element when it forms an “open”
metallocene with the 2.4-di-terf-butylpentadienyl ligand. Like most transition metal pentadienyl complexes, the title compound 1 (shown
on the right) contains pentahapto- rather than
monohapto-bound ligands. Unlike its transition
metal counterparts, however, the metal-carbon
bonds in 1 are noticeably longer than those in the
analogous cyclopentadienyl complexes. Furthermore, the pentadienyl ligands in 1 have an nntieclipsed arrangement, which is unprecedented
for open metallocenes.
T. P. Hanusa * ........................
Synthesis and Crystal Structure of the
“Open” Calcocene [(tBu,C,H,),Ca.thf]
1
A. J. Arce,* Y. De Sanctis,
J. Manzur,
M. V. Capparelli ....................
A cyclic ruthenium trimer without metal-metal bonding, the highly symmetrical trinuclear complex 1 is
formed under mild conditions by the reaction of
[Ru,(CO), z] and diazocyclopentadiene. Insertion of
cyclopentadienyl units into Ru-Ru bonds also
leads to the formation of [Ru,(CO),,(C,H,)] and
the dimer [Ru,(CO),(C,H,),] .
(CO),
Three key steps characterize the highly stereoselective synthesis of the title compound 1 : a thermodynamically controlled intramolecular Diels-Alder reaction of
the vinylsulfonate of 3, the radical cyclization of a derivative of 2, and a reductive
sultone cleavage. Thus, this synthesis starting from 2-acetylfuran requires only 15
steps.
qo
Hy - $Y:
2
1
A i i g i ’ ~ C’lieirr.
.
I I I I . Ed.
EngI. 1994, 33, N o . 21
,:fi
2193-2195
[Ru,(CO),(q5:q‘-C5H,),]:
The First Six1
Me0
2191 -2193
(
y
Membered Ru,C, Ring Formed by Insertion of C,H, Units into Metal-Metal
Bonds of [Ru,(CO),,]
P. Metz.* J. Stoking,
M. Lage, B. Krebs ................. 2195-2197
A Short and Highly Stereoselective Synthesis of the 1,lo-seco-Eudesmanolide Ivangulin
H
3
VCH Verla~sgrsell.c~huft
mbH, 0-69451 Weinheim,1994
o57o-OH33i94j212t-2125 S 1(1.00+
.WO
2125
Micelle-forming substances or polymeric micelles 1 enhance not only the rate of the
hydrogenation of esters of (Z)-2-N-acyldehydroamino acids in water, but also its
enantioselectivity. A high sensitivity of the optical induction to achiral modifiers is
observed for the new precatalyst 2.
A. Kumar, G. Oehme,*
J. P. Roque, M. Schwarze,
R. Selke* ...............................
2197-2199
Increase in the Enantioselectivity of Asymmetric Hydrogenation in Water Influenced
by Surfactants or Polymerized Micelles
BF, 2
*
The longest C, bridge known between two single
metal centers is found in the bimetallic complex 1.
The structure of 1 is best described by the cumulene
resonance form +Re=C=C=C=C=C=Mn. A
very intense rhenium-to-manganese charge transfer
band at 480nm ( E = 6 0 5 0 0 ~ - ’ c m - ’ ) suggests
that the C, ligand acts as a “molecular wire”.
Counterion: BF,
W. Weng, T. Bartik,
J. A. Gladysz * ........................
Re’
ON’
P
‘!Ph,
II
C
II
1
C
II
2 199- 2202
Towards One-Dimensional Carbon Wires
Connecting Single Metal Centers: A
Cumulenic C, Chain That Mediates Charge
Transfer between Rhenium and Manganese
Termini
C
II
G
OC,
II c
o
,
C
I
W
C
,
CI
V. Caliman,
Constructed from six phosphaalkyne units, the
organophosphorus compound P6C6tBu, (1)
can be considered to have a structure derived
from the corresponding tetraphosphacubane
in which two opposite carbon corners have
been replaced by CCP rings. The hexamer 1
therefore has the same structure as the D,,
symmetric (CH), hydrocarbon ~ ~ - [ 3 ~ . 5 ~ ] o c t a hedrane and the hypothetical P,, .
P. B. Hitchcock,
J. F. Nixon,* M. Hofmann,
P. von R. Schleyer* ............... 2202-2204
A Novel Hexamer of tBuC=P: Synthesis,
Structure, and Theoretical Studies
(tmtaa)Zr(f-C,H,)]
6
\
HND
fi
a
VCH I~urlugsgesrllschaftiuft
mbH. 0-69451 Weinheim, 1994
2204-2206
Tetraaza[l4]annulenezirconium(1v) Complexes with Butadiene Ligands and Their
Relationship with Bis(cyclopentadieny1)zirconium(1v) Complexes
H2tm taa
I
Low concentrations of D-fructose and D-galactose do
not hinder the detection of D-glucose with the fluorescence sensor 1. The diboronic acid 1 is easv to
synthesize and forms a cleft structure in which
monosaccharides bind with differing selectivity. The
saccharide-diboronic acid 1 : 1 complexes are readiIy detected by their fluorescence.
2126
L. Giannini, E. Solari,
C. Floriani,* A. Chiesi-Villa,
C. Rizzoli ...............................
YY
The reversible binding of pyridine in complex 1 can be
considered as a model reaction for the incorporation
of a reactive substrate in the coordination sphere of
a metal complex. Compound 1 is the first example of
a complex with a macrocyclic ligand that contains a
metal- butadiene functionality.
T. D. James,
K. R. A. S. Sandanayake,
S. Shinkai* ............................
2207- 2209
N’
A Glucose-Selective Molecular Fluorescence Sensor
HO,
PH
0570-Og33iY4!’2121-2126 S 10.00+ .25:0
Angru Clirm. I n f . Ed Engl. 1994. 33, .No. 21
A regular sequence of naphthalene and anthracene units form the basis of the backbone of the polymer 1. This “molecular board” is obtained by dehydration of the
appropriate 0-bridged unsaturated precursors and should be of interest in areas
such as nonlinear optics and electroluminescence.
M. Loffler,
A.-D. Schliiter,*
K. Gessler, W. Saenger,
J.-M. Toussaint,
J.-L. Brirdas ............................
2209--2212
Synthesis of a Fully Unsaturated “Molecular Board”
On a preparative scale of 10 mg per batch the dioxirane 2 can be synthesized from the diazomethane 1.
Compound 2 is the first dioxirane that is stable in
the solid state at room temperature. An intermediate, probably the carbonyl oxide, can also be kept
for several hours in solution at - 78 “C.
& $pi$
A. Kirschfeld,
S. Muthusamy,
W. Sander* ............................
/o
p=Nz
/
Dimesityldioxirane-A
the Solid State
Dioxirane Stable in
/
1
2
H. Brunner,*
H . Obermeier .........................
Tumoral destruction increases
from 0% to 37% in the dark,
and from 1 9 % to 62% with
subsequent IR irradiation,
when instead of the free ligand 1
its platinum complex 2 is employed against tumor cells.
N
HN
An absolute pK, value of about 36 in acetonitrile is
obtained for porphyrin from its reaction with phosphazene bases. The monoanion 1 is stable in aprotic
solvents and was characterized by NMR and UV/
Vis spectroscopy. The remaining central proton in
the monoanion migrates between the four nitrogen
atoms much faster than the two protons in the parent compound.
2212-2214
l,R=H
2, 2 R = (NH,),Pt
2214-2215
Platinum(n) Complexes with Porphyrin
Ligands-Additive
Cytotoxic and Photodynamic Effect
J. Braun, C. Hasenfratz,
R. Schwesinger,
H.-H. Limbach* ....................
2215-2217
Free Acid Porphyrin and Its Conjugated
Monoanion
1
Insertion of a BH, molecule with simultaneous reduction is observed in the reaction
of 1 with NaBH,. The lability of the methoxy group in the chelate ligand is thought
to favor formation of the unusual product 2.
S. Nlate, P. Guenot,
S. Sinbandhit, L. Toupet,
C . Lapinte,
V. Guerchais* ........................
2218-2219
A Carbene-Iron Chelate Complex as a
Source of a Ferraborane Derivative
1
2
cis,cis-1,2,4-Cyclopentanetriol(2) is introduced as an auxiliary to assist removal of
an r bridgehead hydrogen in non-enolizable ketones 1. Bridgehead functionalization
of 3 to yield 4 can then be achieved by directed metalation or radical substitution.
Examples of 1 include homocubanone and adamantanone.
A
1
2
3
Irrespective of what mobile phase is used the enantiomers of hexobarbital (I) can be separated chromatographically on a fused silica capillary column
coated with Chirasil-Dex. This is shown by their
separation with gas chromatography, supercritical
fluid chromatography, open tubular liquid chromatography, and capillary electrochromatography.
U. P. Spitz,
P. E. Eaton * _......._... . ..._......._. 2220-2222
Bridgehead Functionalization of Non-Enolizable Ketones: The First Preparatively
Useful Methods
4
'%%
C"3
H-
1
V. Schurig,* M. Jung,
S. Mayerr S. Negura,
M. Fluck,
H. Jakubetz ...........................
2222-2223
Toward Unified Enantioselective Chromatography with a Single Capillary
Column Coated with Chirasil-Dex
* Author to whom correspondence should be addressed
New in Angewandte Chemie from 1995: Keywords
In an effort to improve the service we provide for readers, from January 1995 keywords will be assigned to every article
that appears in Angewandte Chemie. These keywords will help readers find specific articles of interest more quickly and
should facilitate literature searches. The keywords will be used for the subject index printed in the December issue.
Authors are requested to provide a maximum of five keywords with their manuscripts (to be listed at the end of the text
before the reference section). The subject index in the December issues of previous years is a useful guide to the
appropriate sort of keywords.
For uniformity please classify compounds of particular elements as "element compounds" and not "element complexes" (e.g., iron compounds and not iron complexes). Furthermore, if the entry under name of the element is not
considered sufficient please classify complexes according to the coordinating atom (e.g. complexes with nitrogen
ligands) or according to the coordinating compound (e.g. arene complexes, carbene complexes).
The editorial office will make every effort to provide a uniform subject index.
BOOKS
Contents
Handbook of Enantioselective Catalysis with Transition Metal Compounds,
Vols. I and I1 * H. Brunner. W. Zettlmeier
0. Reiser ..........................................
2225
Oxford Chemistry Primers:
Chemical Bonding * M. J. Winter
Organometallics 1 * M. Bochmann
Organometallics 2 . M. Bochmann
Bifunctional Compounds R. S. Ward
B. Konig .......................
....................
2225
Scanning Tunneling Microscopy and Spectroscopy. Theory, Techniques
and Applications I).A. Bonnell
W M . Heckl ....................................
2226
Buckminsterfullerenes * W E. Billups, M. A. Ciufolini
The Fullerenes * H . W. Kroto, J. E. Fischer, D. E. Cox
Fullerene C,,, . History, Physics, Nanobiology, Nanotechnology * D. Koruga,
S. Hamerloff. J. Withers, R. Loutfy, M. Sundareshan
The Fullerenes. New Horizons for the Chemistry, Physics and Astrophysics
of Carbon . H. W. Kroto, D. R. M. Walton
A . Hirsch .........................................
2227
Sources A-129
Author Index A-137
Preview A-138
Thank you!
Professor William E. Russey from Huntingdon, PA, USA, passed
on the following correspondence, between Ho Leung Ng, Harvard
University, and Jonathon Houze, Stanford University, which he
came across recently in a USENET bulletin board:
In article ~ng4.779670585@husc7>,ilo Leung Ng <ng4@husc7.harvard.edu> wrote:
>
Hello - I am new graduate student, and I would like to solicit
>opinions on chemistry journals. I am looking for something that offers
>broad coverage of chemistry, with many reviews and news of exciting research.
>Something I can read for fun, but still technical and with references.
>Something analogous to Current Opinions in Biology series or Physics Today.
>Thank you.
>
Try Angewandte Chemie International Edition in English. (Or read it in
German, if you know the language). It has Highlights (very short reviews of
recent work), longer reviews, and plenty of research articles from various
fields of chemistry. I think it's one of the best and most readable
journals out there.
Jonathan Houze
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