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Graphical Abstract (Angew. Chem. Int. Ed. Engl. 111994)

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A Journal of the
Gesellschaft
Deutscher Chemiker
lnternat onal Ed tion in English
3-3111
Pages 1121-1198
COVER PtCTURE
The cover picture shows a bay boletus. xerocomus hadius. The chemical formula of
badion A. a dye found in the cap of this mushroom, is superimposed on the right of
the photo. The identical partial structures .in the formula (highlighted in green and
yellow) were identified with the genetic computer algorithm presented by M.
Wagener and J. Gasteiger on p. 1189 ff. The steps in this algorithm are shown
schematically on the left. This procedure facilitates comparison of structures, a
process required for the analysis of biological activity, the elucidation of biosynthetic routes. or the identification of appropriate starting materials for a synthesis.
(Photography: W. Steglich, Munich).
REVIEWS
The gegenion often exercises a substantial influence on the course of “ionic” organo
alkali-metal reactions. The compounds comprising ions of alkali metals and “carbanions“ are present in solution as monomeric o r aggregated contact ion pairs, or
solvent-separated ion pairs. The gegenion thus changes the electronic and spatial
structure of the anion by charge-localization and pyramidalization. Only through ab
initio calculations can results be obtained without the falsifying influences of solvation and aggregation on the structures of the carbanionoid moiety, which otherwise
prevent comparisons within a group of the periodic table.
Contcnts
C. Lambert,
P. von R. Schleyer* ....___......_.
1129- 1140
Are Polar Organometallic Compounds
“Carbanions”? The Gegenion Effect on
Structure and Energies of Alkali-Metal
Compounds
HIGHLIGHTS
Rates never before achieved for the hydrolysis of
amides are attained by the Cu2(0,) complex I ,
which converts dimethylformamide into the forinate ion in seconds (half-lives of amides in water
are often several years!). The interacting Cu ions
play an important role. Such simple model systems
can provide insights into the structure-activity relationships of enzymes and even lead to the development of highly active catalysts.
M. W. Gobel* ...__....._.........___.
1141 -1 143
Binuclear Metal Complexes a s Efficient Intermediaries in Biochemically Relevant Hydrolysis Reactions
Overall yields up to 100000 times greater than that of
the first, and for almost 40 years the only, total
synthesis of strychnine ( I ) by Woodward et al. (28
steps) are obtained in four new approaches to the
natural product. The strategies and key steps in
these routes are discussed in this article. One approach provides strychnine enantioselectively. another reaches the target molecule in only 15 steps.
U. Beifuss* .............................
1144-1149
New Total Syntheses of Strychnine
0
1
SH
COMMUNICATIONS
Very flexible and antiaromatic versus
relatively rigid and aromatic--that is
the difference
between
[24]porphyrinogen
1 and its
oxidation
product
H
Q
H
[22]porphyrin dication 2. Although
both compounds occur in the
cis,trans,cis,ti-oiis configuration, the
protons along the inner perimeter of 2
are shifted roughly 20.5 ppm upfield.
and the outer protons are shifted approximately 8.4 ppm downfield relative to the corresponding protons in 1.
'
-
o \
0
-
'oe
0
\
/
G . Markl,* H. Sauer, P. Kreitmeier,
T. Burgemeister, F. Kastner, G. Adolin,
H. Noth, K. Polborn ............. 1151-1153
Tetraoxa[22]porphyrin(2.2.2.2)Dication
and Tetraoxa[24]porphyrinogens(2.2.2.2)
2
1
I. G. Gut, J. Wirz* ........__.......
1153-1156
Remarkable stability is shown by the recently observed 3 H isomer 1 of indole (2) (T 2 100 s at pH E 9
and 25°C). The equilibrium constant pK, of the
tautomerization of 2 to 1 is 5.8 k 0 . 2 ; in other words,
the equilibrium concentration of 1 lies in the range
of 1 to 2 ppm. The tautomerization is catalyzed by
acid and-less efficiently- by base.
3H-Indole
'1
H
Two Sn[N(SiMe,),] moieties arranged trans. linked by a 1.4-diaminosubstituted cyclohexane or benzene ring describes the first heteroleptic bis(stanny1ene)s 1 and 2
(R = SiMe,), respectively; the bis(germy1ene) is isomorphous with 2. The replacement of the N(SiMe,), groups for aryloxy groups takes place on addition of
Sn(OAr), to I and 2; surprisingly, the treatment of 2 with SnCl, affords the redox
products 3 and metallic tin.
(R,N)Sn
:a;\
(RZN)S:
RNQR
\ Sn(NR,)
Sn(NR,)
2
1
(R,N)SnCl
\NQG,
R
MeMe
MeMe
MeMe
Me
Br
I
Ph
I
Ph
I
Ph
I
Ph
Synthesis, Structures, and Reactions of
Two Bis(diaminostanny1ene)s and a Bis(diaminogermylene) Containing a Central C,
Ring
CI,Sn(NR,)
3
By simple bromine-lithium exchange a 2,5-dibromophosphole is converted into the
corresponding 2-lithio derivative. This opens a new route to difunctionalized
biphospholes (which are interesting in their own right as building blocks for synthesis) and to the unprecedented, a-linked quaterphosphole 1.
Me
H. Braunschweig, P. B. Hitchcock,
M. F. Lappert,*
L. J.-M. Pierssens ................... 1156-1158
E. Deschamps, L. Ricard,
F. Mathey* ............................
11 58-1 161
Toward Polyphospholes: Synthesis and
Structure of an x-Linked Quaterphosphole
The oxygen analogues of carbenoids 1 and nitrenoids
2. namely the lithiated hydroperoxides 3. are more
electrophilic than the corresponding nonlithiated
derivatives. These “oxenoids” can convert organometallic compounds RM’, including cuprates, into
alcohols under mild conditions.
,Li
X
‘OR
= R,C
~ , X = R N
3, x = 0
G. Boche,* F. Bosold,
J. C. W. Lohrenz ....................
1161-1163
The Oxenoid Character of Metalated
Hydroperoxides O(M)OR: Oxidation of
Organometallic Compounds R’M‘ to R O H
under Mild Conditions
One equivalent of CaZ+and Sr” ions induces the isomerization of the colorless
spirobenzopyrans l a ( n = 1) and 1 b ( n = 2), respectively, to the colored merocyanines 2. Compounds of type 1 thus function as ion-selective chemical sensors.
M. Inouye,* Y. Noguchi,
K. Isagawa ............................
1163-1 166
Sensitive and Selective Coloration of
Cryptand-Type Crown Spirobenzopyrans
for Alkaline-Earth Metal Cations
la, b
2a, b
In sediments and Messel shale, a series of novel hydrocarbons has been identified. They can be considered as the cyclization products of regular all-frans
polyprenols (up to Cd5!).These skeletons have not
yet been found in living organisms. One of these
“molecular fossils” (C33)is shown on the right.
-
Now reductions induced by sunlight are also possible.
P. Schaeffer, J. Poinsot. V. Hauke,
P. Adam, P. Wehrung, J.-M. Trendel,
P. Albrecht,* D. Dessort,
J. Connan ...............................
11 66-1 169
Novel Optically Active Hydrocarbons in
Sediments: Evidence for an Extensive Biological Cyclization of Higher Regular
Polyprenols
G. Pandey,* S. Hajra ............ 1169-1171
0
The photosystem here, which absorbs visible light
and transfers electrons from an electron donor D to
an electron acceptor A and then to a substrate, is
composed of D = Ph3P and A = dicyanoanthracene.
Enones 1 were chosed as substrates. After reduction
to the radical anion they cyclize to form 2. This
conversion is a variant of a cyclization mediated
by tin hydride but without toxic side products.
R = CN. C0,Et; n = 1, 2.
R
1
J. Scholz,* A. Scholz,
R. Weimann, C. Janiak,
H. Schumann ........................
The quinoxaline and phenazine dianions can each be
stabilized by two lanthanocene units, which leads to
the novel binuclear rare-earth complexes with short
La-C and La-N contacts. These La-ligand contacts resemble those in “aromatic alkali-metal
amides”. The phenazine complex is shown on the
right.
The first catalytic oxidative activation of methane in
the gas phase employs high-vacuum conditions and
Pt’ ions generated by laser desorption. In the presence of 0, the initially generated Pt+ -CH, is oxidized to formic acid (65 YO),formaldehyde (25 YO),
and methanol (10%). The picture on the right
shows the most important part of the complicated
catalytic cycle.
Arig”v. Chcnz. 1171.E d Engl. 1994. 33. No. 1I
A Novel Photosystem for Harvesting Visible Light to Drive Photoinduced Electron
Transfer (PET) Reductions: P-Activation
of a$-Unsaturated Ketones for Radical
Cyclizations
1171-1174
N-Heteroarene Dianions as Antiaromatic
Ligands Bridging two Lanthanocene Moieties
R. Wesendrup, D. Schroder,
H. Schwarz* ..........................
,,CH,02”
c, VCH Verlagsgesellschrrff mbH, 0-69451 Weinheim, 1994
1174-1176
Catalytic Pt’-Mediated
Oxidation of
Methane by Molecular in the Gas Phase
oS7U-o83.~~94!1111-i12S
$ 10.00+.25!0
1125
Contents
The "half-probe'' molecule 1, when a constituent of phospholipid vesicles in the
presence of cholesterol in large, but biologically reasonable proportions (over
30 mol Y O )selectively
.
attacks the middle of the bilayer.
S. B. Fredriksen, V. Dolle, M. Yamamoto.
Y. Nakatani.* M. Goeldner,
G . Ourisson * .........................
1176- 1 178
Increased Selectivity of a Simple Photosensitive Probe in the Presence of Large Proportions of Cholesterol
Coordination number two, ten valence electrons, and
highly bent ligands owing to the weak secondary interactions with or.tl7o inesityl substituents- these
characteristic features are present in one (shown on
the right) of the first two thiolato complexes with a
two-coordinate Fe" center. Low coordinate iron
centers of this kind bound to sulfur are of particular
interest in light of the crystal structure of the FeMo
cofactor of nitrogenase.
J. J. Ellison. K. Ruhlandt-Senge.
The C,-symmetric tetrahydrofuranpentamer 1 was prepared in enantiomerically pure
form by a convergent synthesis. Compounds of this type are of interest for the
construction of synthetic ion channels from polyether helices. TBDPS = rBuPh,Si.
U. Koert,* M. Stein,
P. P. Power* ..........................
Synthesis and Characterization of Thiolato
Complexes with Two-Coordinate Iron(1r)
qB;'
1: '
A remarkably simple arylboronic acid reagent for
derivatization of diols enables the determination of
the optical purity of diols by 'H NMR spectroscopy
by the formation of the corresponding esters 1. This
procedure could be particularly valuable as enantioselective bishydroxylations become more widely
used for asymm-etric syntheses.
1111
OMe
Me
K. Burgess,* A. M. Porte ..__..1182-1184
A Reagent for Determining Optical Purities
of Diols by Formation of Diastereomeric
Arylboronate Esters
R . Chiappetta, M. Julve,* F. Lloret,
Y. Journaux,* J.-C. Colin,
G . Blondin .............................
01
.H20 1
H
wo
O\OP O\@/O
H-&HZ-~i
I
H
01
' 'S~-CH,-N-H
'
I
H
1184-1186
Structural and Magnetic Characterization
of a Novel Heptanuclear Hydroxo-Bridged
Copper(ii) Cluster of the Corner-Sharing
Dicubane Type
R. Tacke.* M. Miihleisen,
P. G . Jones ............................
1186- 1188
The First Zwitterionic Optically Active Disilicate with Pentacoordinate Silicon
(+)-I
By reductive coupling of coordinated CO without external reducing agents the p 2 ketenylidene and p3-oxo ligands are generated simultaneously in the reaction of
[Cp,Zr(CO),] with [Zr(O,CNR,),] (R = Et. iPr) to form I . Deoxygenation of
carbon dioxide and acetone by 1 occurs readily and leads to the substitution of the
ketenylidene ligand for a pz-0ligand.
[Cp2Zr3(02CNR2)&,-o)(~,-CCo)l
1180- 1182
J. A. Real, G. De Munno.
An energetically low-lying octet ground state and ferromagnetic exchange interactions between seven
Cu" ions characterize the magnetic behavior of the
complex cation in 1, whose novel Cu,(OH), framework is shown on the right. bpym = 2,2'-bypyrimidine.
Stereospecifically and with surprising ease, the first
zwitterionic isSi,/?5Si'-disilicate( + ) - I was prepared
from (EtO),SiCH,NH, and (R,R)-(
+)-tartaric acid
in aqueous solution. The binuclear complex is optiT I
cally active owing to the two chiral Si(OO'),C units
and the tetradentate tartrato ligands.
K . Harms ..............................
A Convergent Synthesis of 2,5-tu(insLinked Oligo(tetrahydrofuran)s: Potential
Building Blocks for a Polyether Helix with
Ion Channel Activity
1
[Cu,(bpym),(H,o),(oH),I(NO,),
2178-1180
F. Calderazzo, U. Englert, A. Guarini.
F. Marchetti, G. Pampaloni.*
A. Segre .................................
1188-1 189
[Zr,Cpz(O,CNiPr,),(p~-O)(pz-CCO)I, the
First Crystallographically Established
Ketenylidene Complex; A Model for CO
Reductive Cleavage on Metal Surfaces
J. Gasteiger.* M. Wagener ..... 1 189- 1 192
\ P
With a genetic algorithm, a computer-based optimization method that imitates the adaptation methods of nature. the maximum substructure common
to two molecules can be found. Appropriate starting
materials for the target of a synthesis can thus be
found with this method. In an analogous procedure
the largest substructure contained twice in a single
molecule can be identified so that synthesis precursors can be used several times in a synthetic pathway. as exemplified with badion A (1).
The Determination of the Largest Substructures with a Genetic Algorithm: Application in Synthesis Design and in Structural
Analyses of Biological Activity
ccr>
A D,,-symmetric structure with a delocalized rc electron system describes the ground state of s-indacene
(1). although it is a formally antiaromatic system.
These results, obtained by both high-level a b initio
MO methods and calculations based on density
functional theory, are in agreement with the known
structure of 1,3.5,7-tetra-terr-butyl-s-indacene.
.*.........
.-. .___.
1
R. H. Hertwig. M. C. Holthausen,
W. Koch.* Z. B. Maksic ....... 1192-1194
s-Indacene: A Delocalized, Formally Antiaromatic 12 x Electron System
* A u t h o r to whom correspondence should be addressed
BOOKS
The Quiet Revolution: Hermann Kolbe and the Science of Organic
Chemistry A. J. Rocke
G. B. Kuuffinccn ................................
1195
Applied Laser Spectroscopy. Techniques, Instrumentation, and
Applications . D. L. Andrews
N . Ernsting ......................................
1195
K Trernel ........................................
1196
D. Scliinzer .....................................
1197
E. Henrich .....................................
1 198
+
Inorganic Biochemistry. An Introduction
*
J. A. Cowan
Conjugate Addition Reactions in Organic Synthesis
-
P. Petlmutter
Handbook of Hot Atom Chemistry J.-P. Adloff, P. P. Gaspar, M . Imamura,
A. G. Maddock. T. Matsuura, H. Sano, K. Yoshihara
Author Index A-55
Preview A-56
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