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Hydrocarbon Activation with Metal Halides Catalysis of the Jacobsen Rearrangement by (ZrCl4)n in the Presence of Aromatic Hydrocarbons.

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E. T. Clark. P. R. Rudolf. A. E. Martell. A. Clearfield. fiioi-g C/i;fii. A i
164. S9.
P. R. Rudolf: E. T. Clark. A. E. Mdrtell. A. Clcartield. J c'oord. < ' / w i n 1985,
14. 139
B. Bujoli. P. Palvadeau. J. Rouxel. C h i . M o r c r . 1990. 2. 582.
D. M. Poojiiry. Y. P. Zhang. B. Zhang, A. Clearfield. Chiwf. Mare.. 1995, 7.
G. Alberti. U. Costantino. S . Allulli. N . Tomas\ini. J. fiiorg. . V d . C%rw.1978.
411. I I 13. D. M. Poojary, H.-L. Hu. F. L. Campbell. 111. A. Cleni-lield. .4rra
C r ~ w d / o , q iS, c ~ rB
. 1993. 49. 996; K . J. Martin. P J. Squattrito. A. Clearfield.
frior,q. C/uifi.A m / 1989. 15s. 1
G. Cao. H Hong. T. E. Mallouk. Arc. C%oii. Ra.v. 1992. 3.420.
A layered zirconium phosphite-diphosphonate pillared compound with interlayer porosity is also known See G. Alberti. U. Costantino. F. Marmottini. R.
Vivani, P. Zappelli. Aif,qiw. C/wi?i 1993, f(J5, 1396: Aii,qeii.. C h i i . / i f / . Ed.
Dig/. 1993. 3-7. 1357.
M. E. Thompson, Cheii7. M L I I W 1994.
6 . I IhX.
K. Maeda. Y. Kiyozumi, F. Mirukami. Arigcw. Chew 1994. /Oh. 2427; Angrn,.
c ' / i m i . f r i r . Ed. Engl. 1994. 33. 2335.
J. L. Bidenu. C. Payen. P. Palvndeau. B. Bujoli. h r g . C/imi. 1994. 33. 4885.
Depending upon the reaction conditions (temperature. molar composition of
the rcilctmts and solvents) a number of ur;inyl phcny1phosphon;ite phases have
been isolated ;ind characterized. The striictures o f UO2[(H0,PC,.H,)
n H z O and that of an cthanol adduct, UOZ[H0,PC,,H,];C,H,0H c
linear chains. Structural studies on two orthorhombic phases arc nlso in progress.
J. W. Visser. .
&p/. C r ~ ~ s ~ c d h1969.
g r . 2. 89.
A. Larcon, R. B. Von Dreele. GSAS. Gciio.rr/irrd Sirirmuc A i i a / ~ . a i tSi,s/iwi.
Los Alainos National Lihoratory. 1988.
Crystallographic data: Scan range (211) 3-80 increment 0.01 . tinic constant
10 s. rotating anode source (Cu,,). C , H , 0 , U P . 0 . 7 H 2 0 . M , = 43X. space
group P6:im<. (no. 192), = h = 2I.X27(2). c =7.0796(X)A. L'= 2921 A'.
Z = 12. />L,,,c,, = 2.98 Mgm-', T = 23 C No. 0 1 contributing reflections
( K x l K,J 676. no. of geometric observations N,,,, = 20: average distances
[A]used to constrain the bond lengths in the refinement: P 0 1.53(2).
=1.80(2), 0 0 (PO,), 2.55(2), P C l.SO(2). C - C 1.3s; IS structural parameters. 11 profile parameters, R,, = 0.177. R, = 0.12. R, = 0.05.
R,,, = 0.04.(see ref. [I31 for definitions).
D. M. Poojary. D. Grohol. A Clearfield. J. Phi,s. ( ' / i ~ i i i . Solub. in p r e s
The phenyl rings are grouped about the sixfold axes. in such a wey tliat three
rings are in one plane (at z = 0) and the other three at a plane with := 1:2 and
vice versa For a given phenyl group, there are two nearest neighboring phenyl
groups. both at a plane shifted half along the c axis. The interactiona between
the groups from the same channel involve C2 and C3 atoms (C2 C2' 3.78.
C 3 C3' 3.9 A), while that between neighboring channela involve C4 and CS
atoms (C4-C4 3.5, CS-C5' 3.6. C4-CS' 3.8. and C S - C 4 3.8 A). Thc C6
atoms of the adjacent phenyl rings are separated further apart lo accommodate
one of the uranyl oxygen atoms 01.
transition metal halides.['. 31 This approach has a parallel in
organic chemistry-reactions with super acidic
A significant advantage of acidic metals over expensive, low-valent metals in elaborate coordination environments['] is their
straightforward preparation, low cost. and stability towards
We report here on a number of observations concerning the
interaction of alkylbenzenes with ZrCI,. Although ZrCI, is extremely insoluble in noncoordinating solvents, it is very soluble
in CH,Cl, in the presence of a stoichiometric amount of 1,2,4,5Me,C,H2 (durene). The ' H N M R spectrum of the reaction
mixture in CD,CI, initially shows the presence of an unshifted
singlet for the Me groups of durene. but after some time numerous peaks of increasing intensity appear in its vicinity. Addition
of T H F to the solution results in [ZrCl,(thf),]. in addition to
durene and a small amount of other alkylbenzenes. The dissolution of ZrCI, promoted by durene has been interpreted according to Reaction (a).
Hydrocarbon Activation with Metal Halides:
Catalysis of the Jacobsen Rearrangement
by (ZrCIJ,, in the Presence of
Aromatic Hydrocarbons**
The solubility of ZrCl, is also increased in the presence of
other alkylbenzenes, although the hydrocarbon: ZrCI, ratio depends on the arene. In the case of m e ~ i t y l e n e [the
~ ] dissolution
occurs with an arene:ZrCI, ratio of 2: 1, which reflects the lower
basicity of mesitylene compared to that of durene. However,
this technique cannot be extended to C,Me,H and C,Me,, because, though they react with ZrCI,, they form insoluble compounds.
When the CH,Cl, solution of ZrC1,-durene was left standing
for several weeks. significant amounts of C,HMe,, C,Me,,
C,Me,H,, and C,Me,H3 formed, along with some insoluble
compounds. This conversion continued until the starting durene
is completely consumed. Thus the transformation of the ZrC1,durene system in CH,CI, solution can be summarized by
Scheme 1 .
Euro Solari, Fabrizio Musso, Richard Ferguson, Carlo
Floriani,* Angiola Chiesi-Villa, and C o r r a d o Rizzoli
The metal-promoted rearrangement of hydrocarbons involving C-C bond cleavage and formation is of major interest."'
Amongst the more interesting approaches, though not frequently employed, is the use of acidic metal electrophiles such as early
[*I Prof. Dr. C. Floriani, Dr. E. Solari. F. Musso, Dr. R. Fcrguson
lnstitut de Chimie Mintrale et Analytique
Universite de Lausanne. BCH 3307
CH-1015 Lausanne (Switzerland)
Telefiax: Int. code 21 6923905
Prof. Dr. A. Chiesi-Villa, Dr. C. Rizzoli
Dipartimento di Chimica. Universitd di Parma
Viale delle Scienzc. 1-43100 Parina (Italy)
This work was supported by the Fonds National Suisse de la Recherche Scientifique (grant no. 20.40268.94) and by Ciba-Geigy SA (Basel. Swltzerbdnd).
Scheme 1 . 2: R
H ( S O % ) , Me (50%)
We isolated compound 2, [(~6-Me,C,R)Zr,C1,] (R = H,
50%; R = Me, 50%). as a crystalline solid. Its structure, identical to that of 1 and [(tf'-C,Me,)Zr,CI,] (3), and its composition have been proved by an X-ray analysis and by analysis of
the decomposition products arising from the reaction with THF.
To avoid the statistical presence of the C,Me, and C,Me,H
ligands in 2. we synthesized the analogous complex 3 from pure
C,Me, and ZrCI, in 1,2-C1,C6H,. The ' H N M R spectrum of 3
in CDzCll shows two singlets at 6 = 2.20 (low intensity) and
0 = 3.55 corresponding to free C,Me, and zirconium-coordinated C,Me,,. respectively. The structure of 3 is shown in Figure 1 [''I with some selected structural parameters. Some distantly related examples of (@-arene)zirconium(rv) complexes have
been reported recently.["
AIX,, the methyl migration occurs almost exclusively in an intramolecular
Such reactions are believed to proceed
via a carbocation intermediate, as is the case in alkylbenzene
rearrangements promoted by the TaCI,/CH,CI, system'13a1and
in alkane isomerization assisted by CX,!AIX, _I'3b1 Unlike these
cases, we believe that in our reaction a methyl group is transferred intermolecularly from a methyl donor to ii methyl-accepting arene. and this probably does not require a carbocation
intermediate. As a matter of fact, when we performed the reaction at 100'C in 1,2-CI2C,H, with C,Me,, we observed the
formation of partially methylated benzenes and alkylated solStudies in progress are aimed at extending these reactions to
the functionalization of hydrocarbons and other kinds of hydrocarbon rearrangements, and to making these reactions catalytic
in zirconium. In addition, we should mention that the solution
of durene-ZrCI, in CH,CI, can be used as a source of a soluble,
weakly solvated form of dimeric ZrCI,.
E.uperiniental Procedure
Fig. 1 0 R ' f L . P LIC\\I of complex 3 (ellipsoids at 30% probability). Selected distanccs [Aj: Zrl ('I1 2.76212). Zrl ('12 2.587(2). Zrl C13 2.375(2). Zrl Cbl
2.36716). Zi-1 ('I 2.739(6). Zrl C2 2.725(8). Zrl -C3 2.768(7). Zr2-CI1 2.519(3).
Zr? C12 2 f~OY(11. Lr2 ~C142.347(3). Zr?-C15 2.357(4). Bond angles [ 1: C13-ZrlCl3' 94.(1(1). C'I2-Zrl-CI3 151.4(1). C12-Zrl-Cl2' 78.2(1j . CII-Zrl-Cbl 174.7(2),
( . l 4 - Z r X ' l 4 90.4( I ). C12-Zr2-CI4 91 0(1j . Cll-ZrZ-CI2 76.6(1). Cll-Zr2-C15
161 411 ) . Priinctl :itoms denote ii transforination ot'.~.0.5 - 1'. r.Cbl refers to the
centroid of the aroniatic ring.
Complex 3 has a crystallographic mirror plane passing
through both Zr atoms, CI 1, and CI 5. The assignment of an q6
bonding mode to the hexamethylbenzene fragment is supported
by the narrow range of the Zr-C distances [2.725(8)1.768(7)
The terminal Zr-Cl bonds have an average length
of 2.365(9) A. while significant asymmetry is observed for the
bridging chlorine atoms; the longest Zr-Cl distance is to C11,
which is / r m . \ to the q6-C,Me, ligand [Zr 1 -C11 2.762(2) A] .['I
This chlorine atom should therefore be the easiest to ionize.
Indeed, complexes 1-3 should be considered as models of the
precursors for the formation of [(q6-C,Me6)TiCI,]C[Ti2CI,]~.
which is generated from the reaction of C,Me, with a large
excess of TiC'I, in CH2C12.[91The large ionic radius and the
greater acidity of zirconium versus titanium allow the isolation
of the neutral arene complexes 2 and 3 prior to subsequent
ionization processes.
We have investigated the possible roles played by CH,CI,.
including whether it serves as the source of methyl groups. To
rule out this hypothesis, we performed the same durene rearrangement in other solvents such as 1,2-C,H,C12, C2H,Cl4, and
n-octane.""] I n addition, when the reaction was carried out in
CD,CIz we did not observe incorporation of deuterated methyl
groups into the final alkylbenzenes.
The reaction in Scheme 1 is catalytic, albeit to only a limited
extent. Furthermore. complexes 2 and 3 dissolved in CH,C12 are
also able l o promote the disproportionation of durene. The
ZrC1,-assisted rearrangement of C,Me,H is quite similar to that
discussed for durene. The rates of both reactions can be increased considerably by conducting the reaction in 1,2-Cl,C6H,
at 60 c'. or by using a higher ZrC1,:hydrocarbon ratio. We
should mention at this stage that the isomerization of durene
was observed previously by action of concentrated sulfuric acid,
the so-called Jacobsen reaction."
The mechanism of the reaction in Scheme 1 is open. Contrary
to our results. in the alkylation and dealkylation reactions promoted either by H,SO, or Lewis acids such as H i , BF,. and
1 : A solution ofZrCI, (40.0 g. 171.7 mmol) a n d durcne (23.05 g. 171 7 niinmoll in
CH,CI, ( l 0 0 m L j gave a red-violet solution after 15-18 11. T H F (5.1) mL) was
added to a 5.0 m L aliquot of the solution and [ZrCl,(thf),] wah isolated. Durene *as
identilied as the major organic product (by GC-MS) along wit h significant amounts
of C,Me,H and C,Me,,. and all the C,H,Me, isomers. After ;I reaction time of six
inonths a t room temperature. we found that the initial durcne was coinpletely
converted into C,Me,H and C,.Me, in ii 4.3 molar iratio w i t h iiii overall yield of
90%: the durene isomers amounted to only 1 % . iind we did n o t determine the
amounts of the other demcthylated species such as the mcsitylene isomers and the
insoluble products. We indirectly proved that insoluble diarglinethanes containing
bridging CD, units form from benzene and toluene by the action ofCD,CI, assisted
by ZrCI, The nddition of T H F to the final solution gake [ZrCl,(thf),] (95%)
2: A ZrCl,-durene solution in CH,CI, HAS left stmding at iooin temperatiire for
one month. then concentrated to dryness. The solid w a s recrystalli/cd from 1.2CI,C,H, to give 2 (93"/,). Anal. cdkd for C,3H34Cl,6Zr4:C 22.23. H 2.76: found:
C 23.01, H 2.95. Compound 2 decomposed on trcatment w i t h T H F giving a 1 .I
mi\tureofC,,Me,HandC,Me,.CrystaldlrtaforZ [Zr,CI,(C,:H,,j~, J C , , H I 6 ) ,,I.,
orthorhomhic. space group Pninu. N =19.514(3). h =13.266(3). c = X.130(6) A.
V = 2104.6(1.7) A'. Z = 4.
3: A suspension of ZrCI, (2.50 g. 10.7 mmol) in I.2-CI,C6H, ( IXi m L ) and C,Me,
(0.865 g. 5.30 mmol) was heated to boiling until i t became 'I clear solution. The
s o l ~ t i o nh a s then allowed to cool t o ambient temper'iture, affording 3 as ii microcrystalline solid (90%). Anal. cdlcd for C,,H,,CI,Zr,: C 21 94, H 2 8 9 : f o u n d :
C 23.01. H 2.97.
Isomerization of durene' A moderately catalytic isomeriratioii ofdurene to C,Me,
and C,Me,H i n CH,CI, was observed when high durene:ZiC'I, ratios were used.
The conbersion ofdurene to C,Me, and C,Me,H was roughly 40"G complete in one
day when a durene:ZrCI, ratio of 10:l was used. To accelerate the reaction and
demonstrate c;italysis. we used il high ZrC1,:substrete ratio. M'ith ii ZrCI,:durenc
ratio of 4.1. durene i n CH,CI, was completely converted in one day. The first
addition ofdurene was followed by Eeveral others while maint'iining the Same ratio,
with no noticeable loss in activity. I n every case complete converion required one
day. I n this way the conversion of durene assisted by ZrCI, extcnds to more than 20
times the stoichiometric value.
Received: March 1. 1995 [Z7751 IE]
German version: Angew. ('heni 1005. 107. 1621 -1623
Keywords: arene complexes . hydrocarbons * isomerizations
Jacobsen rearrangement Zirconium compounds
[ I ] a ) J. A. Davies. P. L Watson. J. F. Liebman. A. Greenberg.
hon Activurion. VCH. New York, 1990: b) Acrii'olwn unil ~iiii[,ri(iiiuli~iirion
Alkunc,s. (Ed.: C . L. Hill). Wiley, New York, 1989: c ) A L. Shilov. A m r ~ i i o n
of Sulurutrd Hi~lrotrirhons/I?, Trunsitnni Mc~rulC o n i p l i ~ . ~Reidel.
~ ~ ! . Inghain.
MA. 1984: d) W. D. Jones, F. J. Fehcr. A w . C / i ( ~ n i Re\.
1989, 2. 91: cj A. D.
Ryabov, C'/wni. R w . 1990. YO. 403: f ) A. Sen, A w . Chew Rr! 1988. 2 / . 421 ;
gj R. H. Crabtree. C'hem. Rev. 1985. 8 j . 245.
[2] a ) 1. P. Rothwell. Thr Honiogenmius Acrivutioii (I/ C u r h c n - l ~llrogcn
Bonr1.y hr
Efwtropfiiln. M e f a / Si..sriwx\, Chapter 3 in ref. [ l a ] : b) P. L Watson. C - H 5nmI
Aclii'urion with Cofiipl(2.u>.s
of Lritithunid(~.sand Acrinidc~Elciwnts. Chapter 4 in
ref. [I a]; c ) I . P. Rothwell. Tlic Ifoni[)ji[,iio(irraA c t i i ~ t i o f(11
~ C'urIi(n1-Hsr/ro,ycw
h l l d r hx Hi,?/?fiileni G f r l j rl-5loc.k. Lonih~in~ifos
ritiil A (./inirti,M t f a i .SJS~W~,S,
Chapter 5 in ref. (IbJ.
[3] a) J. A. Labinger. A. M. Herring, J. E. Bercaw. J. Am. C h ~ mSnc.
1990. 112,
5628; b) G. A. Luinstra, J. A. Labinger. J. E. Bercaw. ihrd. 1993, 115. 3004; c)
J. A. Labinger. A. M. Herring. D. K. Lyon. G. A. Luinrtra. J. E. Bercaw. I. T.
1993, /I. 895; d ) A. Sen. M. Lin. L.-C.
Horvith. K . Eller, Orgwnm~.ta//ic~
Kao. A. C. Hutson, J. A n . Chem. Soc. 1992, 114. 6385.
[4] a) G. A. Olah. G. K . Surya Prakasb. J. Sommer. Super-Acds, Wiley. New
York. 1985: b) P. Vogel. Carboculion Chenri.srrv. Elsevier, Amsterdam, 1985.
and references therein: c) J. Sommer, M. Muller, K. Laali. N C > NJ. Chrm. 1982,
6 , 3 ; M. Siskin. J. Porcelli, J. Am. Chew. SOC.1974. 96. 3640. and 3641; ibirl.
1976. Y8, 5413: ibid. 1978. 100, 1838.
I S ] ZrCI, (10.0 g. 42.9 mniol) can be dissolved in 100 mL of CH,CI, i n the presence
of mesitylene (10.32 g. 85.9 mmol) in 15-20 h.
[6] Crystal data for 3: C,,H,,CI,Zr,. orthorhombic, space group Pmnu;
( I =19.524(4).
h=13.?18(3). ( ' = 8.355(4);\, V = 2156.2(12)A3. 2 = 4 .
=1.936gcm-'; Mo,, radiation (E. =0.71069A). pMOkn
crystal dimensions 0.21 x 0.30 x 0.38 mm. The structure was solved by the
heavy-atom method starting from a Patterson map calculated using SHELX76 and refined anisotropically for d l non-hydrogen atoms. The high values of
the U,, thermal parameters of the methyl carbons suggested the presence of
some disorder due to a possible noncentrosymmetric structure. We tried to
refine the structure in the noncentrosymmetric space group Pnrt2,. but we did
not succeed because of strong correlations between psendosymmetry-related
parameters. The centrosymmetric refinement was then considered satisfactory
and the high anisotropic thermal parameters attributed to some rotation of
the hexamethylbenzene molecule in the plane perpendicular to the Zr- centroid
direction. The hydrogen atoms were ignored. The refinement was based
on the unique total data and carried out using SHELX-92. For 1948 unique
total reflections [ I > 2cr(1)] collected at room temperature (6 i20 < SO f
and corrected for absorption. the final i 1 R 2 was 0.092 ( R = 0.042 for
1098 unique observed reflections). All calculations were done on an Encore 91
computer. Further details of the crystal structure investigation may be
obtained from the Director ofthe Cambridge Crystallographic Data Centre. 12
Union Road. GB-Cambridge CB2 1EZ (UK). on quoting the full journal
[7] G. D. Gillis. M.-J. Tudoret. M. C. Baird. J. Am. Chnn. Soc. 1993. 115. 2543;
M. Bochmann. G. Karger. A. J. Jaggar. J. Chern. So<,.Cheni. Cfnnmim. 1990,
1038; C. Pellecchia. A. Grassi, A. Immirzi. J. Am. Cheni. Soc. 1993, 115. 1160;
C. Pellecchia. A. [mmirzi. A. Grassi. A. Zambelli. O,.~~oroni~/u//irs
1993. 12.
[8] The Zr-CI distances range from 2.307(2) to 2.655(2) A in polymeric (ZrCI&)":
"5, Krebs. Z. Anorg. A/lg. Chcm. 1970, 378. 263.
[9] a ) E. Solari. C. Floriani. A. Chiesi-Villa. C. GudStlni. J. Cheni. So<,.Chrm.
Commun. 1989, 1747; b) E. Solari, C. Floriani, K. Schenk. A. Chiesi-Villa. C.
Rizzoli. M. Rosi. A. Sgamellotti. Inorg. Chem. 1994. 33. 2018.
[lo] Although the solubility of ZrCI, in the presence of durene in 1,2-CI,C,H4,
C,H,CI,, and octane is far less important than in CH,CI,, we found in all cases
that the same rearrangement of durene occurs.
[I 11 A. Koeberg-Telder. H. Cerfontain. J. Chem. Soc. P(+-kin I1 1977, 71 7; Eur.
Chrni. Pays-Bar 1987. 106, 85: H. Cerfontain, A. Koeberg-Telder. Con. J.
Chcm. 1988, 66. 162.
1121 a) 1. March. Arliwrced Otgunic Chiwvstry. 4th ed.. Wiley. New York. 1992;
b) p. 565 in [12a] and references therein; c) pp. 561 - 563 in [12a] and references
1131 a) E. Solari, C. Floriani. A. Chiesi-Villa, C. Rizzoli. J Chern. Soc.
Chcrii. Cammun. 1991. 841; b) 1. Akhrem. A. Orlinkov. M. Vol'pin, i/nd 1993,
[14] Complete transformation ofC,Me, (1.73 g. 10.7 mmol)wis observed when the
reaction was conducted at 100 -C in I.?-CI,C,H, (100 mL) for 2 3 days with
ZrCI, (5.0g. 21.5 mmol). The GC-MS analysis showed the presence of pentamethylbenzene, durene and isodurene, mesitylene isomers. and o-dichloro(methy1)benzene isomers. all of them in the same ratio
Nonheme Iron Centers in Oxygen Activation:
Characterization of an Iron(m) Hydroperoxide
Marcel Lubben, Auke Meetsma, Elizabeth C.
Wilkinson, Ben Feringa,* and Lawrence Que, Jr.*
Peroxoiron(~ir)complexes are increasingly being considered
as potential intermediates in oxidations catalyzed by nonheme
iron centers in biology. because of anticipated difficulties in
stabilizing high-valent iron-oxo species in the absence of porphyrins."' For example, spectroscopic studies of "activated
bleomycin" (BLM"]), an antitumor drug that effects the oxidative cleavage of DNA and the oxidation of hydrocarbon^,[^'
cumulatively support its formulation as a low-spin hydroperoxidoiron(i11) species.[41A model for "activated BLM" has been
synthesized that mimics its reactivity and gives rise to the same
optical and EPR spectra;[51 however, more detailed spectroscopic data is not yet available. In a related area, alkylperoxoiron(111)complexes have been implicated in hydrocarbon oxidations;[61several have been stabilized at low temperature and
spectroscopically characterized."] To date, however, "activated
BLM" remains the only characterized iron hydroperoxide complex in a nonheme environment. Our own efforts have been
directed at generating analogous species in different but related
nonheme Iigand environments. We thus present here the synthesis and X-ray structufe of I , an iron(1r) complex of a new pentadentate ligand ("N4Py"). Complex I reacts with H,O, to generate a transient purple species 2 which is characterized as a
low-spin hydroperoxoiron(rr~)complex. (The compound numbers 1 and 2 are used both for the Fe" and Fe"' cations, respectively, and also for their perchlorate salts.)
Treatment of N4Py with one equivalent of Fe(CI0,); 10H,O
in a CH,OH/CH,CN mixture followed by vapor diffusion of
ethyl acetate yielded dark red crystals of [Fe(N4Py)(CH3CN)]['I
Prof. L. Que, Jr.. E. C. Wilkinson
Department of Chemistry. University of Minnesota
Minneapolis. MN 55455 (USA)
Telefax: Int. code (612)624-7029
Prof. B. Feringa. Dr. M. Lubben. Dr. A. Meetsma
Department of Organic and Molecular Inorganic Chemistry
Gronnigen Center for Catalysis and Synthesis
University of Groningen
Nijenborgh 4, NL-9747 AG Groningen (The Netherlands)
[**I Financial support of this research by Unilever Research (Vlaardingen. Netherlands) to B. L. F. and the National Institutes of Health (USA) to L. Q. (GM33162) is gratefully acknowledged. E. C. W. thanks the NIH for a predoctoral
t raineeship (G M-07323)
0570-0833!95,'13/3-15/2$ 10.00 + ,2510
A n g ( w . Chern. Inf. Ed. Eng/. 1995, 34, No. 13/14
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presence, rearrangements, metali, hydrocarbonic, catalysing, jacobsen, halide, activation, zrcl, aromatic
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