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Graphical Abstract (Angew. Chem. Int. Ed. Engl. 121996)

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A Journal of the
Gesellschaft
Deutscher
_ _Chemiker
International Edition in English
1996
35/12
-
Pages 1249 1356
COVER PICTURE
The cover picture shows the van der Waals surface (represented by a grid) and the
structure (stick model) of a benzene molecule included in the cavity of a molecular
capsule. This host is composed of two calix[4]arenes that are held together by
hydrogen bonds. The blue space-filling model at the bottom represents the van der
Waals surface of the bottom calixarene, the gray stick model the structure of the
upper calixarene. The host -guest complex is obtained within minutes by simply
stirring a solution containing the calix[4]arene dimer and benzene. J. Rebek, Jr. et al.
report more on p. 1326ff on the affinities of these calixarene capsules to other
molecules.
REVIEWS
Contents
Chiral unsa-metallocene complexes are excellent catalysts for enantioselective carbomagnesations, hydrogenations, polymerizations, and Dieis-Alder reactions. They
can also be employed in stoichiometric amounts as chiral mediators in enantioselective reactions; however, recovery of the metallocene is not always possible. The
future of chiral metallocene catalysts in preparative organic chemistry depends
critically on their cost and ease of preparation.
A. H. Hoveyda,*
J. P. Morken ....... . ................. . 1262- 1284
Predicting structures of solids capable of existence is the first step in planning the
syntheses of solid-state compounds. The modular approach presented here determines such structure candidates by using global optimization methods to find
metastable minima on the potential energy surface. So far the method has been
applied to systems characterized by ionic or van der Waals bonding. The good
agreement with experimental findings suggests that predictions for yet unknown
compounds, for example alkali metal nitrides such as Na,N and Ca,SiBr,, are also
most likely to be correct.
J. C. Schon, M. Jamen* ........ 1286-1304
Enantioselective C-C and C-H Bond
Formation Mediated or Catalyzed by
Chiral ebthi Complexes of Titanium and
Zirconium
First Step Towards Planning of Syntheses
in Solid-state Chemistry: Determination of
Promising Structure Candidates by Global
Optimization
HIGHLIGHTS
Contents
Very selective and under mild conditions. These features characterize the cleavage of C-H bonds in
alkenes and arenes by the cationic iridium(w) complex 1 developed recently by Arndtsen and
Bergman. The extremely high reactivity of this compound is attributed to the presence of separated ion
pairs, evident also in the crystal. The remarkable
tolerance of 1 towards functional groups bodes well
for possible applications in synthesis.
+
J. C. W. Lohrenz,*
H. Jacobsen* .........................
1305-1307
Cationic Iridium(rr1) Complexes: A Step
Towards Synthetic Applicability of C-H
Activation
1B(3,5-C6H3(CF,)Z)41-
1
A dream became reality: Twenty years after the discovery of the basic process,
Sharpless et al. have developed a catalytic asymmetric aminohydroxylation (AA) of
alkenes. This reaction [Eq. (a)J provides an access to such important molecules as
amino alcohols and a-hydroxy-6-amino acids in enantiomerically pure form.
0. Reiser* .............................
1308-1309
The Sharpless Asymmetric Aminohydroxylation of Olefins
NHT~
K~[OSO~(OH)~](Z.O
mol%)
(DHQ),-PHAL (2.5mol%)
* phyCozMe
ph*Co2Me
TsNClNa (3.5equiv)
^. *
vn
tBUOHIH20 lil, 25°C
69%. 82% ee
COMMUNICATIONS
As a neutral, lipophilic, purely organic host, the
macrocycle 1 may deservedly be labeled an "anionbinding counterpart" of a crown ether or cryptand.
Macrocycle 1 was synthesized from the inexpensive
steroid cholic acid. It forms 1 : 1 complexes with fluoride, chloride, and bromide and shows good discrimination in favor of the smaller anions. R =
pentyl.
R/yd
Two silyl substituents without additional H substituents are the features of the bisadducts I, which
are selectively obtained by the reactions of silyllithium compounds 2 with C,, . The single-crystal X-ray
analysis of l a confirms 1,16 or 1,29 addition.
RiR'SiLi 2
R' = R2 = Me,&;
a,
b, R'
=
A. P. Davis,* J. F. Gilmer,
J. J. Perry ................................
1312-1315
A Steroid-Based Cryptand for Halide
Anions
O/R
K)
0
I
I
1
\'
RiR2Si@
\
~
1.16
/ SiR'R;
T. Kusukawa, W.Ando* ....... 1315-1317
,
Reactions of SiIyIlithium with CG0:Isolation and X-ray Crystallographic Characterization of an Unusual Bissilylated-C,,
rBu, R2 = Ph
1.29
Neutralization-reionization mass spectrometry (NRMS) proved the existence of
the highly strained acepentalene 2 generated from the precursor 1. The experimental data agree well with the results of density functional theory computations,
which predict that the Ct singlet 2 is about 3.9 kcalmol-' more stable than the C,,
triplet 2.
M e , S n w
Me,
-ZMe,Sn'
NRMS
0
2
1
Pyrene can be bent by almost 90°. This was confirmed by a crystal structure analysis of cyclophane
I, which reveals an 87.8" bend over the length of the
pyrene moiety and a stretched aliphatic chain (C-CC bond angles up to 119.4'). The signals at highest
field for the bridge protons are at 6 = - 1.47. The
arene's curved surface approximates part of the surface of D,, C,, .
1252
$2
VCH V ~ r l a ~ s g ~ , ~ ~ ,ml hl sHc. l0.69451
~a~
WeiPrhei?n,1996
*
O
w
1
o
R. Haag, D. Schroder, T. Zywietz,
H. Jiao, H. Schwarz,*
P. von R. Schleyer,*
1317-1319
A. de Meijere* .......................
The
Long
Elusive AcepentaleneExperimental and Theoretical Evidence for
its Existence
G. J. Bodwell,* J. N. Bridson,
T. J. Houghton, J. W. J. Kennedy,
M. R. Mannion .....................
1320-1321
1,%Dioxa18](2,7)pyrenophane, a Severely
Distorted Polycyclic Aromatic Hydrocarbon
i)j7o-OX33~96!3S12-12SZ$ lS.00 i .25/0
Angen.. Chem. Inr. Ed. Engl. 1996. 35. No. 12
Contents
Three different anions are contained in the novel lithium complex 1. which has a
"butterfly" structure. The preference of this structure over the common alternatives
lies in the relative bridging abilities of the ligands present. The stability of the
complex was impressively demonstrated by a b initio calculations.
[LiBr . LiN(SiMe,), . iLiOC(tBu)=CH,i2. (tmeda),]
K. W. Henderson, A. E. Dorigo.
P. G. Williard.*
P. R. Bernstein .......................
1322-1324
A Triple Anion Complex Containing Enolate, Amide and Halide-A New Structural
Type in Lithium Chemistry
1
Well-structured physical gels, composed of an organic liquid and a
small amount of a gelator molecule
like the title compound I. are known
to have microstructures of interlinked fibers. A method is described
0
for the determination of the molecu1
lar packing arrangements of the gelator molecules in the fibers, based upon subtracting the X-ray powder diffraction
pattern of the neat liquid component from that of the get and relating the difference
to the pattern of the morphs of the neat gelator solid.
E. Ostuni, P. Kamaras,
R. G. Weiss* ..........................
A capsule with a capacity of about 210w3 (shown
schematically on the right) is formed by the dimerization of two calix[4]arenes. Encapsulation of guest
molecules such as benzene, fluorobenzene, and
pyrazine within the capsule occurs on a time scale of
minutes at room temperature.
B. C. Hamann, K. D. Shimizu,
J. Rebek, Jr.* .........................
1326-1329
1324-1326
Novel X-ray Method for In Situ Determination of Gelator Strand Structure: Polymorphism of Cholesteryl Anthraquinone2-carboxylate
Reversible
Encapsulation of
Molecules in a Calixarene Dimer
Guest
-
A heterogeneous palladium catalyst enables the hydrostannation of alkenes with both
great efficiency and generality. The method is illustrated for the allylic alcohols
shown in Equation (a) (R = Ph (96%), 2-fury1 (92%)).
(a)
A reduction of the CO partial pressure is sufficient to obtain single crystals of
[Pd6CI,,] from the equilibrium (a) in thionyl chloride (solv.) at room temperature.
The single-crystal and powder X-ray diffraction characterization of this Pd" chloride
IS described.
2 PdCIZi,, + 2 CO,,,,,,
* Pd*C~4(C0)21i,,,",
(a)
Deep red, oxidation- and hydrolysis-sensitive crystals are formed by the title compound 1. the first derivative of the tetrahedro-tetragermane Ge,H,. It was prepared
according to Equation (a), and isolated and characterized in crystalline form as
2(tBu3Si),Ge;(tBu,Si),.
In these crystals three of the four tBu,Si groups of 1possibly as a result of interactions with the (tBu,Si), molecules-are not arranged
in radial symmetric manner in the Ge, tetrahedron, but are slightly bent.
4 GeClz. dioxane
+6
tBu3SiNa
- 2 tBu,SiCl, - 4 dioxane
6 NaCL)
(a)
(fBu3si)4Ge4
1
A new method for the catalytic asymmetric synthesis
of macrocycles is based on the intramolecular
cyclopropanation of long-chain diazoacetates containing a double bond. Thus, for example, with
[Ch(MeCN),](PF,) in the presence of a chiral bis(dihydrooxazole) ligand, the 15-membered ring lactone
1 was formed not only with excellent regioselectivity
(ratio of 15-membered to 10-membered ring is 25: 1 )
but also with remarkably high enantioselectivity
(90 %
M. Lautens,* S. Kumanovic.
C. Meyer ................................
Heterogeneous Palladium-Catalyzed
Regioselective Hydrostannation of Alkenes
D. Belli Dell'Amico,* F. Calderazzo,*
F. Marchetti, S. Ramello ....... 1331-1333
Molecular Structure of [Pd,CI,,] in Single
Crystals Chemically Grown at Room Temperature
N. Wiberg,* W. Hochmuth,
H. Noth, A. Appei,
M. Schmidt-Amelunxen ........ 1333- 1334
Tetrakis(tri- tert-butylsily1)-tetrahedro-tetragermane (tBu,Si),Ge,-The
First Molecular Germanium Compound with a Ge,
Tetrahedron
M. P. Doyle,* C. S. Peterson.
D. L. Parker, Jr. ....................
'
0
1329-1330
1334- 1336
Formation of Macrocyclic Lactones by
Enantioselective Intramolecular Cyclopropanation of Diazoacetates Catalyzed by
Chiral Cu' and Rh" Compounds
CC).
A n p w CIwn Inr Ed. E P I ~ 1996.
I.
35. N o . 12
(" VCH
Vcrla~sgc.~~~llsclluft
rnhH, 0.69451 Wemhrim. 1996
0570-0833i96/3512-1253 $ 15.00+ -2.5 0
1253
Revision is needed. The proposed
structure of 1 for konbamide, a
calmodulin antagonist isolated from
the sea sponge Theonella sp., must be
reconsidered. Both cyclic peptides of
structure 1 containing L- and D-bromohydroxytryptophan were synthesized by bromination of the protected cyclic peptide. Their N M R spectra and HPLC traces were found to
differ from those of the natural
product, although the mass spectra
are identical.
U. Schmidt,* S. Weinbrenner
MeLeu
Ala
1336- 1338
What is the Structure of the Calmodulin
Antagonist Konbamide from Theonella sp.?
Synthesis of Two Isomers by Direct
Biomimetic Introduction of Bromine in
Hydroxytryptophan-Containing
Cyclic
Peptides
BhTrp
COOH
1
Leu2
Exclusive mono-insertion into one of the polar metal-metal bonds is an apt description of the reaction of thermally stable ZrFe, and ZrRu, complexes 1 with methyl
isocyanide [Eq. (a); M = Fe, Ru]. Thus surprisingly, the second of the two polar
Zr-M bonds in 1 as well as the distorted tetrahedral coordination geometry of the
Zr atom remain intact. The low degree of steric congestion in 1 is manifest in a rapid
rotation about the Zr-M bonds that cannot be frozen out even on cooling to 180 K.
The cyclophane 1 is the first functional model for the enzyme pyruvate oxidase in which
flavin and thiazolium prosthetic groups are arranged close to a well-defined binding
site. It catalyzes the oxidation of 2-naphthaldehyde to methyl 2-naphthoate in
MeOH/Et,N with high efficiency and complete reaction selectivity.
S. Friedrich, L. H. Gade,*
I. J. Scowen, M. McPartlin ..__1338-1341
A Chelate-Amidozirconium Fragment as
Building Block for Unsupported Trinuclear
ZrM, Heterobimetallic Complexes (M =
Fe, Ru, Co)
P. Mattei, F. Diederich * . _ _ _ _1341
___ 1344
A Flavo-Thiazolio-Cyclophaneas a Functional Model for Pyruvate Oxidase
0
NKN.C4H9
1
3 CICH3
It could hardly be easier! The enantiomeric ratio of unprotected natural as well as
artifical amino acids can be determined by 'H N M R spectroscopy with an accuracy
of & 1 % in aqueous solution after coordination to a C,-chiral palladium complex
[Eq. (a); R = Me, Ph; R-R = -(CH,),-1.
1254
c; VCH I/i.rlugsxesell.~~li~i~
mhH. 0-69451 Weinl?eOn. I996
B. Staubach, J. Buddrus*
______
1344-1346
Determination of the Enantiomeric Ratio
of Unprotected Amino Acids by N M R
Spectroscopy with C,-Chiral Palladium
Compounds
0570-0X33!Y6/3512-/2S4 S /S.OO+ -2510
Angm'. Clirm. lnt. Ed. EngI. 1996. 35. No. 12
The heterogenization of chiral homogeneous catalysts is possible by occluding them
in polydimetliylsiloxane membranes. Examples are the synthesis of the first heterogeneous Jacobsen catalyst, which catalyzes the epoxidation of olefins, and the novel
immobilization of Ru-BINAP, which is active in the enantioselective hydrogenation
of ketones. The modified membranes are as efficient in these reactions sketched
below as the homogeneous catalysts.
I. F. J. Vankelecom,* D . Tas.
R. F.Parton. V. Vdn de Vyver,
P. A. Jacobs ...........................
1346-1 348
Chiral Catalytic Membranes
.
~~~~~
* Author t o whom corresnondriice 5hoiLld
he oddrea\cd
~~
Molecular Modeling of Inorganic Compounds * P. Comba, T.W. Hambley
R. J. Depth ...................................
On Being a Scientist: Responsible Conduct in Research
G . B. Kuufjmun
Enzyme Catalysis in Organic Synthesis. A Comprehensive Handbook.
Volumes 1 and 2 . K. Drauz, H. Waldmann
F: Theil ............................................
.._.....__.______...____....._
1349
- -
Keyword Index 1352
1349
1351
_ -
Author Index 1353
Preview 1354
Corrigendum 1348
- .- - - - -
I
1I
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