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Carbothdrate Nanotubes.

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1327 and 1995,34, 1209-1212; J) A. G. Johnston, D. A. Leigh, A. Murphy,
J. P. Smart, M. D. Deegan,J Am. Chem. SOC.1996,118,10662-10663, k) D.
Whang, Y.-M. Jeon, I. Heo, K. Kim, ibid. 1996, 118, 11 333-11334.
[5] G. Schill, Curenones, Rolaxunes and Knots, Academic Press, New York, 1971.
[6] a ) J. S. Lindsey, N e w J Chem. 1991, 15, 153-180; b) J. P. Mathias, C. T. Seto,
G. M. Whitesides, Science 1991,254, 1312-1319; c) D. Philp, J. F. Stoddart,
Angew. Chem. 1996, 108, 1242-1286; Angew. Chem. In[. Ed. Engl. 1996,3S,
1154-1 196.
[7] F. Diederich, C 0. Dietrich-Buchecker, JLF. Nierengarten, J.-P Sauvage,
J Chem. SOC.Chem. Commun. 1995, 781 -782.
[8] J:F. Nierengarten, V. Gramlich, F. Cardullo, F. Diederich, Angew. Chem. 1996,
108,2242-2244; Angew. Chem. Inr. Ed. Engl. 1996,35, 2101-2103.
[9] C. Bingel, Chem. Ber. 1993,126, 1957-1959.
[lo] M. Asakawa. W. Dehaen, G. L'abbC, S. Menzer, J. Nouwen, F. M. Raymo, J. F.
Stoddart, D. J. Williams, J . Org. Chem. 1996, 61, 9591 -9594 and references
[ll] All new compounds were fully characterized by fast atom bombardment
(FAB), matrix assisted laser desorption ionization time-of-flight (MALDITOF). or liquid secondary ion (LSI) mass spectrometry, and by IR, UV/Vis,
and 'H and 13C NMR spectroscopy. All precursors to 12.4PF6 were also
characterized by elemental analysis.
[12] a) A. Hirsch. I. Lamparth, H R. Karfunkel, Angew. Chem. 1994, 106, 453455; Angeu. Chrm. Inr. Ed. Engl. 1994,33,437-438; b) F. Djojo, A. Herzog,
I. Lamparth. F Hampel, A. Hirsch, Chem. Eur. J 1996, 2, 1537-1547.
[13] Q. Lu, D I. Schuster. S. R. Wilson, J Org. Chem. 1996, 61, 4764-4768.
[14] a) A. Pasquarello, M. Schliiter, R. C. Haddon, Science 1992,2S7, 1660-1661;
b) R. Zansai, P. W Fowler, Chem. Phys. Letr. 1995, 238, 270-280.
[15] The [2]catenane 12.4PF6wasconstructed within the input mode of Macromodel 5.0 ( F Mahamadi, N. G. K. Richards, W. C. Guida, R. Liskamp, M. Lipton,
D. Caufield, G. Chang, T. Hendrickson, W C. Still, J Comp. Chem. 1990, 11,
140-467). The geometry was subsequently optimized by energy minimization
with the Polak-Ribiere Conjugate-Gradient (PRCG) method, the AMBER*
force field, and the Generalized Born Surface-Accessible (GB/SA) solvation
model for H,O. The global minimum was searched for by molecular dynamics
with stepwise simulated annealing performed in one step of 10 ps, followed by
two steps of 20 ps in conjunction with the PRCG method, the AMBER* force
field. and the GB/SA for H,O. The simulated temperature was decreased from
300 to 150 and finally to 50 K; a bath constant of 5.0 ps was applied at all steps.
The time step was maintained at 1.5 fs in the first two steps and increased to
2.0 fs in the final step.
a) F. Diederich, U.Jonas. V. Gramlich, A. Herrmann, H Ringsdorf, C. Thilgen. Helv. Chim. Acru 1993,76,244-2453; b) F. Arias, Q. Xie, L. Echegoyen,
Y. Wu. Q Lu, S . R. Wilson, J Am. Chem. SOC.1994, 116, 6388-6394; c) F.
Arias. L. A. Godinez, S. R. Wilson, A. E. Kaifer, L. Echegoyen, ibid. 1996,
118, 6086-6087.
B. L. Allwood, N. Spencer, H. Shahnari-Zavareh, J. F. Stoddart, D. J.
Williams, J Chem. SOC.Chem. Commun. 1987, 1064-1066.
Titrations wererunat [ 8 ] - 1 0 - 4 ~ a n d[9.2PF6]=10-4-10-2~,andK,values
were evaluated with a nonlinear curve fitting program. Maximum observed
upfield shifts (Adobs),,, and calculated shifts for saturation binding (Ad,,,) for
the ring protons of the proximal and distal hydroquinone rings are 0.22
(Ad,,, = 0.473+_0.068)and 0.25 (Ahsai = 0.435+0.042), respectively.
a) W Vetter. E. Logemann, G. Schill, Org. Muss. Spectrom. 1977, 12, 351 369; b) P. R Ashton, C. L. Brown, 1. R. Chapman, R. T. Gallagher, J. F. Stoddart, Terruhedron Lert. 1992, 33, 7771-7774; c) C. Dietrich-Buchecker, E.
Leize, J:F. Nierengarten, J.-P. Sauvage, A. van Dorsselaer, J Chem. Soc.
Chem. Commun. 1994,2257-2258.
P. L. Anelli, P R. Ashton, R. Ballardini, V. Balzani, M. T. Gandolfi, T. T.
Goodnow, A. E. Kaifer, D. Philp, M. Pietraszkiewicz, L. Prodi, M. V. Reddington. A. M. 2. Slawin, N. Spencer, J. F. Stoddart, C. Viceut, D. J. Williams,
J. Am. Chem Soc. 1992, 114, 193-218.
a) D. B. Amabilino, J. F. Stoddart, D. J. Williams, Chem. Muter. 1994, 6,
1159-1167; b) P. R. Ashton, C. G. Claessens, W Hayes,S. Menzer,J. EStoddart, A. J. P. White, D. J. Williams, Angew Chem. 1995, 107, 1994-1997,
Angen. Chem. Int Ed. Engl. 1995,34, 1862-1865.
J.-C. Chambron. C. 0. Dietrich-Buchecker, J.-P. Sauvage, Top. Curr. Chem
1993, 165, 131 -162.
Carbohydrate Nanotubes**
Giuseppe Gattuso, Stephan Menzer,
Sergey A. Nepogodiev, J. Fraser Stoddart,* and
David J. Williams*
Large cyclic oligosaccharides, which can be defined as compounds incorporating more than eight monosaccharide residues
in their macrorings and often possessing internal cavities of
nanometer dimensions, are accessible from both natural
sources['1 and from total chemical syntheses.[*' However, on
account of the difficulties associated with either a) the isolation
of the pure natural products or semi-synthetic compounds, or
b) their availabilities in reasonable quantities from chemical
syntheses, the physicochemical properties of the solid-state
structures and superstructures of these large cyclic oligosaccharides have been somewhat superficially studied. It is only recently, for example, that the higher cyclodextrin (CD) homologs
6-CD,[31E - C D ,and
~ ~ 17-CDL5]
have been obtained as sufficiently
pure samples to be subjected to such detailed investigations.
This situation contrasts sharply with the extensive studies that
have been carried out on the chief members of the CD family
composed of six, seven and eight a-(1 + 4)-linked D-glucopyranose residues, namely a-CD, B-CD, and y-CD, respectively.
These compounds, as well as numerous inclusion complexes,
have been throughly characterized in the solid state by X-ray
and neutron diffraction methods161 and solid-state NMR spectro~copy.'~]
Amongst the large cyclic oligosaccharides, crystallographic data are available only for 6-CD1'] and z-CD.f4'Previously, we s y n t h e s i ~ e d [ ' ~a* ~series
of novel CD analogs
composed of alternating D- and L-rhamnopyranose (R) and Dand L-mannopyranose (M) residues, including the first examples
(RR and MM series) of achiral cyclic oligosaccharides and the
largest (so far) synthetic cyclic oligosaccharide 5-RR built up of
14 alternating D- and L-rhamnopyranose residues. The crystal
structures of 1-MM (a-CD analog) as well as 2-RM and 2-RR
(y-CD analogs) have been reported.['* lo'
X-ray crystallography reveals that, in the solid state, the cyclic
octasaccharide 2-RR['01 assembles in infinite stacks to form
nanotubes of approximately 1 nm in diameter in a manner similar to that exhibited''] by the octasaccharide 2-RM. This stack[*] Prof. J. F. Stoddart, Dr. G . Gattuso, Dr. s. A. Nepogodiev
School of Chemistry
University of Birmingham
Edgbaston, Birmingham, B15 2TT (UK)
Fax: Int. code +(121)414-3531
e-mail :
Prof. D. J. Williams, Dr. S. Menzer
Chemical Crystallography Laboratory
Department of Chemistry Imperial College
South Kensington, London, SW72AY (UK)
Fax: Int. code +(171)594-5804
Angew. Chem. tnr. Ed. Engl. 1997.36. No. 13/14
Synthetic Cyclic Oligosaccharides, Part 3. Part 2: ref. [lob].
0 V C H Verlagsgesellschaft m b H , D-694Sl
Weinheim, 1997
ing motif is closely reminiscent of the nanotubes formed by
cyclic peptides composed of alternating D and L amino acids
reported by Ghadiri and co-workers.“ However, the contrast
between the regular superstructures sustained by these highly
symmetrical cyclic oligosaccharides and the more disordered
packing exemplified by the larger members of the CD familynamely y-CD,[12,6c1 6-CD,rSIand E-CD’~’-~Sstriking. Here we
report the results of X-ray crystallographic investigations on
3-RR. This achiral cyclic decasaccharide displays quite a remarkable structure and superstructure in the solid state.
The X-ray analysis[’31of a crystal produced by vapor diffusion of Me,CO into an aqueous solution of the cyclic decasaccharide 3-RR reveals a structure comprising two crystallographically independent, C,-symmetrical macrocycles A and B
(Figure 1). The two cyclic decasaccharide molecules have similar geometries, and each exhibits departures from ideal S , , symmetry. In A the radii of the polygon formed by the ten glycosidic
oxygen atoms are 6.53 to 7.23 A, whereas in B they are in the
range of 6.73 to 7.21 A. Although the planes of the 01-Dand
a-L-rhamnopyranosyl residues (those containing C2, C3, C5,
and the ring 0 atom) are inclined approximately orthogonally
to the mean plane of the macroring, as defined by the ten glycosidic oxygen atoms, they exhibit a distinct alternating pattern of
inward and outward tilt angles that range between 77“ and 81“
in A and 76“ and 85” in B (Figure Ib). The overall regularity of
the molecular geometry is demonstrated by the conformation of
the pseudo-ten-membered ring (Figure 2) formed by the ten
glycosidic oxygen atoms. which adopts an approximately “allgauche” geometry with alternating torsional twists of about
+76“ about each 0-0 “linkage”.
Inspection of the packing of the A- and B-type molecules
shows each of them to be arranged in an approximately closepacked hexagonal array that extends in the crystallographic b
and c directions (Figure 3). Adjacent molecules in both the b
and c directions are offset by the thickness of about half a ring.
However, there are no intermolecular hydrogen bonds in either
case. In the a direction, the A- and B-type molecules form a
slightly sheared alternating stack creating a nanotube-like arrangement (Figure 4). The mean interplanar separation between A- and B-type molecules is about 7.4A. A particular
point of interest is that, within each stack, the A- and B-type
molecules are not in register. Furthermore, and probably more
0 VCH V2rlagsgesellschofi mbH, 0-6945f
Weinkeim, 1997
Figure 1. a) Space-filling and b) ball-and-stick representations of the C,-symmetrical solid-state structure of 3-RR (only molecule A is shown). The numbers beside
the dashed lines indicate the distances [A] between adjacent pairs of glycosydic
oxygen atoms and their radial distances from the center of the cyclic decasaccharide.
a) Red = 0 atoms; gray = C atoms; white = H atoms. b) Red = 0 atoms; shaded
circles = C atoms.
Figure 2. Polygon formed by the ten glycosidic oxygen atoms (red balls) of 3-RR
(only molecule A is shown). The distances [A] from the mean plane of the molecule
are shown in black beside each oxygen atom, and the “torsional angles” beside each
significantly, they have different cyclic sequences for the glycosidic bonds between the a-D- and cr-L-rhamnopyranosylresidues;
that is, the sequence is clockwise in A, and counterclockwisein B.
This disrotatory stacking is in contrast with the conrotatory
arrangement present in 2-RMtg1and 2-RR,”O1 where the molecules in each stack are in register with each other. There are no
hydrogen bonds between the macrorings within each stack. Included Me,CO and H,O molecules lie both within and between
the channels formed by the cyclic decasaccharide molecules.
0570-0833J97/3613-1452$17.50+ S O / O
Angew. Chem. Int. Ed. Engl. 1991, 36, No. 13/14
Figure 3. Distorted, close-packed hexagonal array of 3-RR molecules (only molecule A is shown). Red = 0 atoms; grey = C atoms; white = H atoms.
Since 3-RR crystallizes in the form of nanotubes with an
internal diameter of about 1.3 nm, it adds to the two examples
of cyclic octasaccharides already reported (namely, 2-RM and
2-RR)I9. "1 which sustain this intriguing superstructure in the
solid state. Given the fact that these compounds share with the
naturally occurring CDs an ability"'] to form inclusion complexes with other molecules, they could find themselves enjoying
many biomedically-directed and materials-oriented applications in the future.
Figure 4. View of one of the discrete nanotubular stacks of 3-RR in the solid state
a) down the stackes and b) from the side (showing also the A-B-A alternation of the
independent, disrotatory cyclic decasaccharides). Red = 0 atoms; grey = C atoms;
white = H atoms.
Received: January 28, 1997 [Z10050IE]
German version: Angew. Chem. 1997,109,1615-1617
Keywords: carbohydrates
supramolecular chemistry
- cyclodextrins - oligosaccharides -
[l] Natural and semi-synthetic examples: a) higher members of the CD family
such as &CD, z-CD, <-CD, and q-CD, which are composed of 9, 10, 11, and
12 D-glucopyranose repeating residues, respectively (D. French, A. 0. Pulley,
J. Effendberger, M. Rougvie, M. Abdullach, M., Arch. Biochem. Biophys. 1965,
111, 153-160); b) cyclic F-(1 + 2)-glucans incorporating 17 to 40 0-glucopyranose residues (M. W. Breedveld, K. Miller, Microbial. Rev. 1994, 58, 145161); c) cyclic 8-(1 + 3)-glucans with 10 repeating units (P. E. Pfeffer, S. F.
Osman, A. Hotchkiss, A. A. Bhagwat, D. L. Keister, K. M. Valentine, Carbohydr. Res. 1996, 296, 23-37); d) cyclic glucans with 8-(1 --+ 3) and 8-(1 + 6)
types of interglycosidic linkages containing more than 11 monosaccharides (N.
Ifion de Iannino, R. A. Ugalde, Arch. Microbiol. 1993, 159, 30-38); e) a
unique microbial dodecasaccharide related to an enterobacterial common antigen (E. V. Vinogradov, Y. A. Knirel, J. Thomas-Oates, A. S. Shashkov, V. L.
Lvov, Carhohydr. Res. 1994, 258, 223-232).
[2] Review on synthetic cyclic oligosaccharides: G. Gattuso, S. A. Nepogodiev,
J. F. Stoddart, Chem. Rev. 1997, submitted. A few large ring synthetic
cyclic oligosaccharides have been reported: a) N. K. Kochetkov, S. A.
Nepogodiev. L. V. Backinowsky, Tetrahedron 1990,46,139-150; b) H. Kuyama, T. Nukada, Y. Ito, Y. Nakahara, T. Ogawa, Carbohydr. Res. 1995,
268, ClGC6; c ) H. Driguez, J.-P. Utille, Carbohydr. Lett. 1994, I , 125128
[3] I. Miyazawa, H. Ueda, H. Nagase, T. Endo, S Kobayashi, T. Nagai, Eur. J.
Pharm. Sci. 1995,3, 153-162.
[4] H. Ueda, T. Endo, H. Nagase, S . Kobayashi, T. Nagai in Proceedings of the 81h
lnfernational Symposium on Cyclodexrrins (Eds.: J. Szejtli, L. Szente), Kluwer,
Dordrecht, 1996, 17-20.
Angew. Chem. Inr. Ed. Engl. 1997, 36. No. 13/14
[S] T. Endo, H. Ueda, S. Kobayashi, T. Nagai, Carbohydr. Rrs. 1996,269, 369373.
[6] a) W. Saenger in Inclusion Compounds, Val. 2 (Eds.: J. L Atwood, J. E. D.
Davies, D. D. MacNicol), Academic Press, London, 1984,pp. 231 -259; b) K.
Harata in Inclusion Compounds, Vol. 5 (Eds.: J. L. Atwood, J. E. D. Davies,
D. D. MacNicol), Oxford University Press, Oxford, 1991, pp. 311-344;c) K.
Harata in Comprehensive Supramolecular Chemistry, Vol3 (Eds. : J. Szejtli,
T. Osa), Elsevier, Oxford, 1996, pp. 279-304.
[7] P. R. Veregin, C. A. Fyfe, Carbohydr. Res. 1987, 160, 41-56.
[8] T. Fujiwara, N. Tanaka, S. Kobayashi, Chem. Lett. 1990, 739-742.
191 P. R. Ashton, C. L. Brown, S. Menzer, S. A. Nepogodiev, J. F. Stoddart, D. J.
Williams, Chem. Eur. J. 1996, 2, 580-591.
[lo] a) S. A. Nepogodiev, G. Gattuso, J. F. Stoddart in Proceedings of the 8th
Inrernational Symposium on Cyclodexrrins (Eds.: J Szejtli, L. Szente), Kluwer,
Dordrecht, 1996, pp. 89-94; b) P. R. Ashton, S. J. Cantrill, G. Gattuso, S.
Menzer, S. A. Nepogodiev, A. N. Shipway, J. F. Stoddart, D. J. Williams,
Chem. Eur. J.,1997,3, 1299-1314.
[ l l ] a) M. R. Ghadiri, K. Kobayashi, J. R. Granja, R. K. Chadha, D. E.
McRee, Angew. Chem. 1995, 107, 76-78; Angew. Chem. Int. Ed. Engl. 1995,
34, 93-95; b) M. R. Ghadiri, Adv. Muter. 1995, 7, 675-677; c) M. Engels,
D. Bushford, M. R. Ghadiri,J Am. Chem. Soc. 1995,117,9151 -9158;d) J. D.
Hartgernik, J. R. Granja, R. A. Milligan, M. R. Ghadiri. hid. 1996, 118,
[12] a) K. Harata Bull. Soc. Chem.Jpn. 1987,60,2763-2767; b) J. Ding, T. Steiner,
W. Saenger, Acta Crystallogr. B 1991, 47, 731 -738.
1131 Crystal data for 3-RR: C,,H,,,O,,~6Me,CO-lOH,O,M , = 1990.0, triclinic,
space group Pi,a =15.130(6), b =19.077(5), c = 20.017(5) k, , a =72.74(2),
p = 87.60(3), 7 = 88.60(3)", V = 5513(3) A', Z = 2 (two independent
= 1.20 g ~ m - ~ ,
molecules, each with crystallographic C , symmetry), pCnlcd
= 8.76cm-', 1 =1.54178 A, F(OO0) = 2144 Crystal dimensions
0.33 x 0.13 x 0.07 mm (plate-shaped prism), Siemens P4!RA diffractometer
with Cu,, radiation (graphite monochromated), w scans, T = 178 K. The crys-
0 VCH VerlagsgesellschaJtmbH, 0-69451 Weinheim, 1997
0570-083319713613-14533 17.50+-.50/0
tal slowly desolvated during data collection. Of 7686 independent reflections measured ( 2 6 s 100") 4846 had
I, > (201,) and were considered to be observed. The data
were corrected for Lorentz and polarization factors, but
not for absorption. The structure was solved by direct
methods. The Me,CO solvent molecules were disordered
over seven partially occupied positions, and the H,O
molecules over 13 positions. Hydrogen atoms within the
60 "C
25 "C
macroring were located from A F maps and refined applying distance constraints with riding isotropic thermal
parameters, U(H) = 1.2 U,,(C,O). Anisotropic refinement of all the exocyclic atoms of the sugar moieties, the
full-weight H,O molecules and six of the Me,CO molecules; the remainder were held isotropic. R , = 0.141 and
wR2 = 0.379 based on FZ.Allcomputations werecarried
Scheme 1. Principle of the biphasic oxidations (F-phase = perfluorinated s( dvent, E = starting material,
out with the SHELXTL 5.03 package.
- The crystallo= product).
graphic data (excluding structure factors) for the structure reported in this paper has been deposited with the
Cambridge Crystallographic Data Centre as supplementary publication no.
small or negligible leaching of the metal salts in the organic
CCDC-I00 130. Copies of the data can be obtained free of charge on apphcaphase and a trivial product isolation by phase separation. An
tion to The Director, CCDC, 12 Union Road, Cambridge CBZIEZ, UK (fax:
excellent chemoselectivity was obtained in the case of the epoxint. code + (1223) 336-033; e-mail:
Transition Metal Catalyzed Oxidations
in Perfluorinated Solvents**
Ingo Klement, Henning Liitjens, and Paul Knochel*
ide synthesis.
The required perfluorinated ligand, the 1,3-diketone 1, was
prepared by the condensation['] of the methyl ester 2 with the
methyl ketone 3 in the presence of NaOMe (1 equiv) in diethyl
ether ( O T , 12 h, then 25 "C, 48 h, 80% yield). The reaction of
the perfluorinated 1,3-diketone 1 with the appropriate metal salt
MCl, (M = Ni, Ru) in the presence of a base furnishes the
desired complexes 4 a and 4 b in 81 and 62 YOyield, respectively.
These were readily soluble in perfluorinated solvents (Scheme 2)
leading to green and purple solutions, respectively.
Perfluorinated hydrocarbons are chemically inert compounds
that have found useful applications, especially as artificial blood
NaOMe, ether
substitutes.['' As a consequence of their low tendency to under- c7F, J O M e + C7Fr5
. ..
go van der Waals interactions, they solubilize well a range of
25 "C, 48 h
gases['] and are immiscible with many organic solvents at room
1: 80 %
temperature. However, a good miscibility with some organic
~ ~ ' properties,
solvents is observed at higher t e m p e r a t ~ r e .These
which were used first for synthetic applications by Horvath and
RabaiJ3' make perfluorinated hydrocarbons ideal solvents for
organic reactions in which gases serve as one r e a ~ t a n t . ' ~ . ~ '
Furthermore, the temperature dependence of the miscibility
of perfluorinated solvents with organic solvents can be advantageously used for enhancing the reaction rate by obtaining a
monophasic system during the reaction. By cooling down the
4a: 81 %
mixture at the end of the reaction, a biphasic system is formed,
Scheme 2. Preparation of the perfluorinated complexes 4a and 4b.
which allows easy separation of the reaction products and recovery of the perfluorinated solvent (Scheme 1). Recently, we
have used perfluorinated solvents for oxidizing organometallic
compounds, such as organozinc derivatives, to give polyfuncThus, treatment of an aldehyde of type 5 with oxygen in a
tional hydro peroxide^.'^^ Under these conditions, organobomonophasic solvent system (toluene/perfluorinated decalin) at
ranes could be oxidized stereoselectively with oxygen to give
64 "C in the presence of the nickel catalyst 4a (3 mol%) furnishalcohols.[61Herein, we report a new practical method for the
es the corresponding carboxylic acid of type 6 in yields of
biphasic oxidation of aldehydes, sulfides, or olefins to give car71 -87% (Scheme 3). The reaction tolerates several functional
boxylic acids, sulfoxides or sulfones, and epoxides, respectively,
groups (ester, chloride, tetraisopropylsilyl(T1PS)-ether) and
in good to excellent yields, which uses a transition metal catalyst
proceeds as well with aromatic as with aliphatic aldehydes.[']
(Ni, Ru) bearing perfluorinated ligands. These chemical proNo leaching of the catalyst is observed (Figure 1) and the
cesses combine an efficient direct oxidation with oxygen with a
catalytic system can be easily recovered (by phase separation)
and reused again as shown in the case of p-chlorobenzaldehyde
["I Prof. Dr. P. Knochel, Dr. I. Klement, DipLChem. H. Liitjens
(5a). The yield of the reaction was still 70% after six reaction
Fachbereich Chemie der Universitat
cycles (Scheme 4). Similarly, this catalytic system can be used
Hans-Meerwein-Strasse, D-35032 Marburg (Germany)
Fax: Int. code +(6421)28-2189
for the oxidation of sulfides 7 to sulfoxides 8 and sulfones 9
e-mail: Knochel@pslSI
(Figure 1, Scheme 5 ) . The reaction required the presence of
[**I We thank the DFG (Schwerpunktprogramm "Peroxidchemie" and Leibniz
the optimum quantities are 1.6 equiv for
prize) and the Fonds der Chemischen Industrie for generous financial support,
the oxidation to sulfoxides and 5 equiv for the oxidation to
and Elf-Atochem (France), Witco AG, BASF AG, Bayer AG, Chemetall
GmbH, and SIPSY S . A. (France) for the generous gift of chemicals.
0 VCH ~rlagsgeseilsehafimbH. 0-69451
Weinheim, 1997
0570-0833/97/3613-1454 $17.50+ .SO10
Angew. Chem. Int. Ed. Engl. 1997,36, No. 13/14
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