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Graphical Abstract (Angew. Chem. Int. Ed. Engl. 81995)

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A Journal of the
Gesellschaft
Deutscher Chemiker
International Edition in English
1995
3418
835-942
Pages
COVER PICTURE
The cover picture shows a space-filling model of a porphyrin quinone model compound (1 b in the article with 2 H instead of Zn), which can be used to simulate and
analyze the first step of the charge separation in photosynthesis (shown schematically). Investigations of this kind have allowed the study of the factors contributing to
the high efficiency of the charge separation in the photosynthetic reaction centers.
More about the recent investigations on porphyrin quinones is reported by H .
Kurreck and M. Huber on p. 849ff.
REVIEWS
Contents
The 100% quantum yield in the primary step of photosynthesis, namely the light-induced charge separation, is seen as a challenge by many research groups, whose aim
is the complete understanding of its mechanism. Here time-resolved spectroscopic
studies of porphyrin quinones, models of the pigments of the photosynthetic reaction center, are presented.
H. Kurreck,* M. Huber ....._....._849-866
Highly potent, well-tolerated, and few side effects are
the promising characteristics of relatively small peptides that are contained in the salivary gland secretions of bloodsucking animals such as vampire bats
and leeches as anticoagulants. Hirudin and its
mimetics, for example, interfere with the complex
process of blood clotting by directly inhibiting the
key enzyme thrombin in a novel mechanism. Several
structure-activity relationships of the complex formation could be explained with the aid of-the structure of the r-hirudin/thrombin
complex (shown on the right).
J. Dodt* ...................................
Angeu. Chrm. Int. Ed. Engl. 1995. 34. No. 8
$3
VCH Verlagsgesellschafi mhH, 0-69481 Weinheim, 1995
Model Reactions for Photosynthesis-Photoinduced Charge and Energy Transfer between Covalently Linked Porphyrin and
Quinone Units
867-880
Anticoagulatory Substances of Bloodsucking Animals: From Hirudin to Hirudin
Mimetics
0870-0833;98/0808-0837$ 10 OO+ .25.f1
837
HIGHLIGHTS
Contents
HO
A gene library has been conceived for the construction of multienzyme complexes from natural and
altered building blocks. The first encouraging results have been achieved with polyketide synthases
(PKSs): enzyme hybrids were formed by “mixing”
genes coding for PKSs, which provide novel polyketides such as 1. The ring frameworks, configurations, and/or functional groups of these novel compounds depend on the manipulated genes.
Excitation of a particular stretching vibration
in the reagent ion NH; influences the course
of its reaction with ND,. The extent of
charge transfer (a), proton transfer (b), and
deuterium abstraction (c) depends on how
the unbrella mode and the symmetrical
breathing mode are excited. Thanks to the
work of Zare et al. discussed here, the goal of
controlling the reaction channels of complex
molecules is a little closer.
J. Rohr* .....................................
CH,
881 -885
Combinatorial Biosynthesis-An
Approach in the Near Future?
%
0
\
CH3
/
1
NH:
+ ND,
NHf
+ ND3
NH:
+ ND,
-
-
NH,
+ ND:
(a)
K.-H. Gericke* ..........................
NH,
+ ND3H+
(b)
Control of Ion-Molecule Reactions in the
Gas Phase
--
NH3D+ + ND,
(c)
885-886
COMMUNICATIONS
Small change-large effect: If some of the carboxylato ligands in the coordination
sphere of the anion in 1, which contains the butterfly-like [Mn,(p,-O),] unit, are
replaced by dicarboxylato ligands by treatment with potassium hydrogen phthalate,
the title compound 2 containing an Mn,,O,, framework in its anion is formed. It
is the largest Mn/O aggregate discovered to date.
(NnBu,f[Mn,O,(O,CPh),(H,O)I
1
2
M. A. Halcrow, J. C. Huffman,
G. Christou* .............................
0 VCH
=
889-891
A Nickel@) Azide Cubane: Characterization of the Magnetic Exchange Interactions
Mediated by a Triply Bridging Azide Group
Bound End-On
[Ni,(p3-N3)4(dbm),(EtOH),1
An unsupported W -W multiple bond between centers having different oxidation states is found in the
homonuclear complex 1, which is formed from
[W,(OiPr),(iBu),], a complex containing a W=W
bond. Dimers of this kind with mixed oxidation
states arise because tungsten can bind hard as well as
soft ligands. Such complexes should display interesting reactivity.
838
887-889
Octadecanuclearity in Manganese
Carboxylate Chemistry: K,[Mn
(OzCPh)zz(Phth)z(HzO),] (PhthHz
phthalic acid)
K,[Mn, ,O, 6(0,CPh),,(~hth),(H,0)~l
A ferromagnetic exchange interaction that is not influenced by the distortion of the cubane framework
of 1 (see picture; only the 0 atoms of the EtOH and
dbm- ligands are shown) and is mediated by the
end-on-coordinated p3-azide bridges has been detected for the first time. Although the unusual
[M4(q1-p3-N3),]core is also displayed by a Pt complex, 1 is the first parmagnetic example. (dbmH =
dibenzoylmethane) .
R. C. Squire, S. M. J. Aubin,
K. Folting, W. E. Streib,
D. N. Hendrickson,*
G. Christou* .............................
Verlugsgesellschufi mbH, 0-69451 Weinheim,1995
P
1
M. H. Chisholm,* K. S. Kramer,
W. E. Streib ................................
891 -893
Complexes with Polar W-W Multiple
Bonds: [W,(OiPr),L(dmpe),] (L = (H)z,
CO) and [Wz(0)4(~-O){W(CO)(dmPe),~*1
0570-0833i9Sj080S-OS38 $10.00+ .25/0
Angew. Chem. Int. Ed. Engl. 1995, 34, No. 8
Contents
With a new multienzyme system with cofactor regeneration based on a sequential
action of glycosidase and glycosyltransferase, a semipreparative scale synthesis of
the cell epitope NeuSAca(2 -+ 3)Galp(l + 3)GalNAc 1 was achieved. Although the
participating enzymes have maximum activities at very different pH values, a satisfactory optimization of the synthesis was possible.
V. Kien,* J. Thiem .....................
893-895
A Multienzyme System for a One-Pot
Synthesis of Sialyl T-Antigen
OH
HO
1
AcHN
OH
OH
NHAc
<: q;
Despite the potential stabilization of diradical intermediates
through the phenyl groups, 2
the thermal dimerization of
$"rt i
g c * Ph
(Ef-I ,3-diphenyl-I .3-butadiene
Ph
S
D
does not follow a diradical
D 1
H D
mechanism as previously assumed, but a concerted pathway. The case examined here is the dimerization of the
deuteriated diene 1 giving 2, which proceeds suprafacially with regard to both diene
and dienophile.
A description as vertex-connected square double pyramid fits
the coordination polyhedrons
of the two platinum centers in
the anion 1 of Li,Pt2H,. The
ternary hydride can be synthesized from LiH and Pt sponge
under a hydrogen pressure of
1250 bar. The lithium counterions are eight- and sevenfold coordinated.
H
I
J. Mulzer,* K. Melzer ................ 895-898
The Dimerization of (E)-l,3-Diphenyl-l,3butadiene Proceeds Suprafacially with
Respect to Both Components: Evidence
for a Concerted 14 + 21 Cycloaddition
W. Bronger,* L. ri Brassard ....... 898-900
5-
1
Li,Pt,H,, a Complex Hydride Containing
Isolated [Pt,H,]'- Ions
H
Porphyrin arrays may act as light-harvesting devices which mimic the photosynthetic
capture of light. Until now the construction of a variety of arrays has been restricted
by the lack of suitable methodology for porphyrin synthesis. A fully conjugated,
aldehyde-appended porphyrin building block has been made and its potential
demonstrated with the one-step synthesis of dimers and trimer 1.
Ph
A. K. Burrell, D. L. Officer,*
D. C. W Reid ............................
900-902
Aldehyde-Appended Tetraphenylporphyrin:
A New Building Block for Porphyrin
Arrays
Ph
Ph
Ecologically sound chemistry relies on the development of new, environmentally
friendly synthetic methods in which few toxic substances are used. Copper powder
was found to be a suitable initiator for the addition in Equation (a) (R', RZ = H,
alkyl, (CH,),COOMe). This initiator is not only cheap but also nontoxic, easily
removed, and readily recyclable.
J. 0. Metzger,*
R. Mahler ..................................
902-904
Radical Additions of Activated Haloalkanes to Alkenes Initiated by Electron Transfer from Copper in Solvent-Free Systems
(a)
I
Anxew. Chem
IN/. Ed. Engl. 1995. 34, No. 8
0 VCH
Verlugsgesellschujt mbH. 0.69451 Weinhrim. I995
OS70-0833/95/0~08-0839
S I0.OOf .2S10
839
Contents
A new metal ion sensor capable of detecting nanomolar concentrations ( < 1 ppb) of
CuZf is made from mixed vesicles of a novel pyrene-labeled metal-chelating ligand
D. Y Sasaki, D. R. Shnek,
D. W. Pack, F. H. Arnold* ........ 905-907
and distearoyl phosphatidylcholine. When copper is added, the fluorescence
monomer intensity emitted at 377 nm greatly increases, while the intensity of light
emitted at 470 nm decreases. This effect is probably due to the dispersal of the
fluorescent lipid throughout the matrix upon metal binding and is depicted schematically below.
Metal-Induced Dispersion of Lipid Aggregates: A Simple, Selective, and Sensitive
Fluorescent Metal Ion Sensor
New “oligourea”-baSed peptidomimetics are the subject of this communication. Two
new derivatives of this type, including the Leu-enkephalin analog 1, have been
prepared by addition of suitably protected isocyanates to amino acids supported on
Rink’s amide resin. The chemistry described is designed for solid-phase approaches
to combinatorial libraries by split syntheses.
Remarkably stable even at room temperature towards elimination are the 1,2-transglycosyl samarium(Ir1) species of type 2. The stability of these species, which contrasts sharply with that of glycosyl lithium counterparts, is the decisive factor for the
high 1,2-trans selectivity of the synthesis of the C-glycoside 3 by reductive samariation of anomeric sulfones of type 1 in the presence of carbonyl compounds.
K. Burgess,*
D. S. Linthicum, H Shin ........... 907-909
Solid-Phase Syntheses of Unnatural Biopolymers Containing Repeating Urea Units
D. Mazeas, T. Skrydstrup,*
J.-M. Beau* ...............................
909-912
A Highly Stereoselective Synthesis of
1,2-trans-C-Glycoside via Glycosyl
Samarium(m) Compounds
3
Reduction of 1 with sodium or tert-butyllithium yields the diene dimer 3. The key
intermediate, the strongly pyramidalized alkene 2, dimerizes to give a cyclobutane
dimer, which then leads to 3. Compound 2 can also be trapped as a Diels-Alder
adduct with 1,3-dienes.
.
912-914
Synthesis, Chemical Trapping, and Dimerization of 3,7-Dimethyltricyclo[3.3.0.03.’]oct-l(5)-ene: [2+2] Retrocycloaddition of the Cyclobutane Dimer
.
I
P. Camps,* M. Font-Bardia,
F. Perez, X. Solans,
S. Vazquez .................................
I
2
1
3
An - N r C and a - C r N group bonded to CH, describes the structure of the title
compound 1. The unstable compound 1 was obtained analytically pure for the first
time and characterized spectroscopically. The X-ray crystal structure analysis enables a direct comparison of the isomeric nitrile and isocyanide functions. First
investigations on complexes of 1 show that low-valent metal complex fragments
coordinate preferably to the isocyanide group.
J. Buschmann, D. Lentz,* P. Luger,
G. Perpetuo, D. Scharn,
S. Willemsen ..............................
914-91 5
Synthesis, Structural Investigation, and
Ligand Properties of Isocyanoacetonitrile
CN-CH,-NC 1
840
C VCH Verlugsgesellschaft mhH, D-69451
Weinheim, 199s
0S70-083319SjO808-0840S 10.0Oi .2SlO
Angew. Chem. Int. Ed. Engl. 1995, 34, No. 8
Contents
An arrested migration of a hydrido
ligand from a ruthenium center to a
p-q'.q'-bound alkenyl group results
in the bonding mode in the products
2 of the reaction of terminal alkynes
HC=CR with 1. These products can
be considered to represent the last
step of the hydrogenation of an
alkyne to an alkene at a heterobimetallic center. R = Ph. CH,Ph,
CH,OMe, CH,OH.
[(PPh,),(CO)Re(pH),Ru(CH,CN)(PPh,),l
1
PPh3
C
IlCR
l
Ph,P
2
High asymmetric induction is achieved in the diastereoselective alkylation of cyanohydrin carbanion
1 (& = 82 94 O h ) . The synthesis of optically active
tertiary cyanohydrins demonstrates how P-chiral
auxiliaries temporarily linked to the substrate
through heteroatoms can be used in asymmetric
synthesis
0
L'
2
,P
p h y \ p ' , ~ o
~
CN 0" N'
,Me
Me'
1
A complex with an eight-membered A14F4 ring in which pairs of Al atoms are bridged
by Ph,Si units is the unexpected product of the reaction of [(Cp*AI),] with Ph,SiF,
[Eq. (a)]. The formation of 1 can be explained in terms of the marked fluorophilicity
of [(Cp*AI),]. Reaction of [(Cp*AI),] with (tBuSb), yields [(Cp*AI),Sb,], the first
organometallic compound to contain an aluminium-antimony bond.
[(Cp*AI),]
+ 2 Ph,SiF,
-
[((Cp*AIF),SiPh,},]
I
Unprecedented Mode of Bonding for
Olefins on Bimetallic Complexes: An
Agostic Interaction of a spz C-H Bond
with a Ruthenium Center in Addition to a n
bond to a Rhenium Center
T. Schrader* ..............................
917-919
A Chiral Cyanohydrin Phosphate for
Carbonyl Umpolung-Stereoselective
Synthesis of Tertiary Cyanohydrins
S. Schulz, T. Schoop, H. W. Roesky,*
L. Haming, A. Steiner,
R. Herbst-Irmer .........................
919-920
Synthesis and Structure of Organometallic
Compounds with (A12Si), and AI,Sb,
Frameworks
1
Two interdependent steps appear to be involved in the C0,-mediated electrophilic
substitution of cyclic amines in the c( position. The key finding is that the lithium
carbamate I is not lithiated with tBuLi to any extent, but reacts only after addition
of electrophiles like Me,SiCI to give the desired a-substitution product 2.
COzLi
Z. He, L. Plasseraud, I. Moldes,
F. Dahan, D. Neibecker,
M. Etienne, R. Mathieu* .......... 916-917
I
Li0,C
1
S. C. Ball, I. Cragg-Hine,*
M. G. Davidson, R. P. Davies,
A. J. Edwards, I. Lopez-Solera,
P. R. Raithby, R. Snaith ........... 921 -923
Lithium Intermediates during the sc-Lithiation and Subsequent a-Substitution of Heterocyclic Amines in the Presence of CO,
1
SiMe,
L
+
Oxidation of half-sandwich chromium complexes of
type I (R = H, Me) with halogens afforded the first
carbyne complexes 2 (X = C1,Br) of chromium in a
high oxidation state. With tBuNC or P(OMe), these
complexes can be converted into thermally stable
products. which were structurally and spectroscopically characterized. Counterion : CI -, Br -.
A. C. Filippou,* B. Lungwitz,
K. M. A. Wanninger,
E. Herdtweck .............................
924-927
Aminocarbyne Complexes of Chromium
in a High Oxidation State-Synthesis,
Structure, and Reactivity
[ ( I ~ ' - C , R , ) ( C O ) , C ~ ~ C N 1~ P ~ , ~
A value of 2.71 p, for the effective magnetic moment
between 100 and 300K is determined for 1. This
magnetic moment supports the assumption of a
triplet ground state for 1. The bis(nitroxy1) diradical, which melts only at 180 "C with decomposition,
could be characterized by X-ray crystallography. It
has a distinctly more planar conformation than the
analogous monoradicals.
t
$:pg
0'
I
0
1
K. Inoue, H. Iwamura* ............. 927-928
2-[p-(N-tert-butyl-N-oxyamino)phenyl]4,4,5,5-tetramethyl-4,5-dihydroimidazol-3oxide-1-oxyl, a Stable Diradical with a
Triplet Ground State
Even at 30 K 1,l-dimethylsilene (1) reacts smoothly with formaldehyde in a thermal
transformation to give trimethylsiloxycarbene (2). This singlet carbene is extremely
photolabile and rapidly rearranges on irradiation with visible light (1> 570 nm) in
a 1,2 migration of the silyl group to give aldehyde 3. According to CCSD(T)/631G(d,p) calculations on the parent silene, reaction takes place via a van der Waals
complex and a diradical intermediate.
M. Trommer, W. Sander,*
C.-H. Ottosson, D. Cremer* ..... 929-931
Reaction of 1,l-Dimethylsilene with
Formaldehyde
n
3
2
1
The highest enantioselectivity yet for a hydrohoration
(98 % ee) was achieved with the ferrocenyl ligand 1,
R’ = R3 = Me, R2 = H, Ar = 4-CF3C,H,, in the
Rh-catalyzed reaction of styrene with catecholborane. The influence of the substituents on both the
pyrazolyl and phosphano fragments was studied,
and the observations tentatively interpreted in terms
of the varying electronic asymmetry they engender
at the metal center.
R2
\
I/
a:
I
A. Schnvder. L. Hintermann.
A. Togni* ..................................
-
I
931 -933
Strong Electronic Effects on Enantioselectivity in Rhodium-Catalyzed Hydroborations with Novel Pyrazole-Containing
Ferrocenyl Ligands
* Author to whom correspondence should be addressed
BOOKS
N . Braun ............................................
935
Namen- und Schlagwortreaktionen der Organischen Chemie T. Laue, A. Plagens
Organic Syntheses Based on Name Reactions and Unnamed Reactions
A. Hassner, C. Stumer
H. Butenschon ....................................
935
Chemical Generation and Reception of Radio- and Microwaves
A. L. Buchachenko, E. L. Frankevitch
M . Goez .............................................
936
Instrumental Methods for Determining Elements
B. D. Pollard
*
L. R. Taylor, R. B. Papp,
.
-
*
Keyword Index 938
Preview 940
Events 934
Author Index 939
842
6
VCH Verlagsgesrllschafr mbH, D-694Jl Weinhelm, 1995
0570-0833~9Sj080R-OR42$10.00+ ,2510
Angew. Chem. Int. Ed. Engl. 1995, 34, No. 8
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