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Catalysis of the Hydrolysis of Phosphoric Acid Diesters by Lanthanide Ions and the Influence of Ligands.

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20 C ) : 6
([ReOJ).
42.04(CH2): "Oj'H) NMR (D,O. 54.21 MHz. 20 C): 6 = 562.9
1019.2 ([ReO,]'). Correct elemental analysis.
Complexes 2 b and c were prepared analogously
=
Received: July 2. 1993 [Z61851E1
German version Angm CIimi. 1993. 105. 1768
a) W. A. Herrmann. Angm.. Clicvn. 1988. IO(/. 1269 --1286: Ang~ir.Cllrni.
In/. Ed. €fig/. 1988. 27. 1297- 1313: b) W. A. Herrmann. J. G. Kuch1er.G.
Weichselbaumer. E. Herdtweck. P . Kiprof. J. Orgufionief. Chmi. 1989.377.
351 -370: c) W. A. Herrmann. M. Ladwig. P. Kiprof. J. Riede. ihid 1989.
371. C13 -C17: d) W.A. Herrmann. C. C. Romso. R. W. Fiscber. P.
Kiprof. C. de Meric de Bellefon. Angni.. Chen. 1991. 103. 183-185:
Angm.. Chrnr. I n / . Ed. €ng/. 1991, 30. 185- 187.
Complex 2a crystallizes from water at 25 C in the triclinic space group Pi
(no.2) with u = 685.1(2). h = 880.6(4), c =1108.4(3) pm. 2 =109.77(1).
{j = 96.36(2).
7 = 93.45(2) . Z = 2 .
V = 622 x 10" pm'.
p ',,,id =
3.276 g ~ m - ~
F(000)
.
= 556, Mo,, radiation. C A D 4 Enraf-Nonius. OJ
scan. max. 90 s. 2383 measured reflections ( I < M < 25 ). h(0/8). A( - 1O /
10). /(- 13,'13). 2102 independent reflections, of which 2066 with
I ~ l . O u ( 1used
)
ti? the refinement. structure solution with Patterson methods. All hydrogen atoms were detected from difference Fourier syntheses
and were freely refined. N o intensity correction, empirical absorption correction on the basis of Psi scan data ( p = I 9 7 cm- I ) , Larson's extinction
parameter 21.39, K = x(lI6,l - /F,II,xII.;ll
= 0.015: R , = [xii.(/Fol
lF,1)*/~1i1F,,1~]'= 0.016. residual electron density + 0.64,-0.72 e , k ' .
Further details of the crystal structure investigation may be obtained from
the Fachinformationsszentrum Karlsruhe. Gesellschaft fiir wissenschaftlich-technische Information mbH. D-76344 Eggenstein-Leopoldshafen ( F R G ) on quoting the depository number CSD-57636, the names of
the authors. and the journal citation.
a) W. A. Herrmann. P. Kiprof. K. Rypdal. J. Tremmel. R.Blom. R.Alberto. J. Behm. R. W. Albach. H. Bock. B. Solouki. J. Mink. D. Lichtenberger.
N. Gruhn. J Am. Clirni. S o . . 1991. 113. 6527-6537; b) I. A. Degnan.
W. A. Herrmann, E.Herdtweck. Clieni. Ber. 1990. 123. 1347-1349.
2bcrystallized from water at 25 C in the triclinic space group Pi (no. 2)
with (I =738.9(2). h = 914.3(2). c = 1229.4(3) pm, 3 = 83.68(2). [j =
77.99(2). ;= 89.29(2) Z = 2, V = 807 x 10'pm'. prd,rd= 2.785 gcm-'.
F(OO0) = 624; Mo,, radiation. C A D 4 Enraf-Nonius. o scan. max. 50 s.
6045measnred reflections (1 < 0 < 2 5 ) , h - WX).A-(-lOilO), /(-14!14),
2785 independent reflections. of which 2506 with f > 3.0n(O used for the
refinement. structure solution with Patterson methods. All hydrogen
atoms detected from difference Fourier syntheses and were freely refined.
No intensity correction. empirical absorption correction on the basis of Psi
scan data ( / I = I 5 3 c m - ' ) . Larson's extinction parameter 23.15. R =
R, = [XW(lFoI - /FcI)2.'X~i.IF~/21'
=
Z(li& - IKil IIFol = 0.018:
0.019. residual electron density + 0.92/-0.85 e , k ' For further details
of the crystal structure investigation see ref. [2].
a ) K. Wieghardt. C. Pomp, B. Nuber. J. Weiss. fnorg. CIwni. 1986. -75,
1659-1661: b) C. Pomp. K. Wieghardt. P o l i ~ l i e r / r o1988.
~i
7. 2537-2542:
c) G. Bohm. K. Wieghardt, B. Nuber, J Weiss. Angwi'. Clicni. 1990. 102.
832-834, Angeii.. Chrni. I t i t . €d. EngI. 1990. 29. 787-790.
Preparation as for 2a. yield > 95%. colorless crystals. Spectroscopic data
for 2b: IR (KBr): i.[cm-'] = 3345(m). 3400(in). 1471(m). 921(vs. v(Re0)
800(m). ' H N M R (D,O.
of [ReO,]'), 912(vs, v(Re0) of [ReOJ).
400 MHz. 20 C): 6 = 2.70 (s. 9H. CH,). 3.15-3.50 (m. 12H. CH,);
1 7 0 j i H ; NMR (D,O. 54.21 MHz. 20 C ) : 6 = 562.4 ([ReOJ). 751.7
([ReO,]'). Spectroscopic data for 2c: I R (KBr): ifcrn-'] = 2980(m).
2920(m). 1620(m). 1449(m). 1413(m). 927(vs, v(ReO) of[ReO,]+). 91O(vs.
v(ReO) of[ReO,]-). 583(m, br, v(CS)). ' H N M R ([DJDMSO. 400 MHz.
20 C): 6 = 3.51 (s, 12H. CH,); ' - 0 ; ' H j NMR([D,IDMSO. 54.21 MHz.
20 C): b = 569.5 ([ReOJ), 781.5 ([ReO,J'). Correct elemental analyses
for 2 b and 2c. The analogous complex [(C,H,2S,)Re0,][BF,] was prepared from [NH,I[ReO,l: H. J. Kiippers. B. Nuber, J. Weiss, S. R. Cooper.
J Clwii. Soc. Clieni. Coninirm. 1990. 979 -980.
Despite the covalent structure, here too. a partial ReO, structure is already
evident in the IR spectrum: IR (KBr): i.[cm-'1 = 909(vs. v(ReO)) typical
of free [ReOJ): W. A. Herrmann. F. E. Kiihn. C. C. RomHo. M. Kleine.
J. Mink. Chem Ber .. in press.
Complexes 2a.c were heated in a dynamic He atmosphere from 50 to
700 C a t a rate of 10 K m i n - ' in a thermobalance TGA 7 (Perkin Elmer).
The gaseous decomposition products were analysed with a mass spectrometer QMG 420 (Bakers). 2 a : extrapolated onset of the first step. 217 C ,
weight loss from 191 to 244 C : 1.7% (H,O); from 244 to 337 C : 12.1%
(H,O); from 337 to 522 C: 17.5% (CO,); 2c. extrapolated onset of the
first step: 1x5 C: weight loss from 156 to 247 C: 8.8% (H,O. CO,.
CH,CH,. CH,S): from 247 to 352 C: 9.4% (H,O. CH,CH,): from 352
extrapolated onset
to 559 - C - 8.4% (CO,). For comparison: Re,O:bpy:
ofthefirst step:332 -C:weight lossfrom221 to445 C: 16.7%(bpy):from
445 t o 690 C: 25.3% (CO,. CO). Re,O,: extrapolated onset: 240 C.
W. A. Herrmann, W. R. Thiel. F. E. Kiihn. R. W. Fischer. M Kleine. E.
Herdtweck. W. Scherer. J. Mink. fnorg. C/imi.. in press.
.
[lo] P. Kiprof. W. A. Herrmann. F E. Kiihn, W. Scherer. M. Kleine, M. Elison,
K.Rypdal. H. V. Volden. S. Gundersen. A. Haaland. Bull. So(. C/rim.Fr.
1992.1-79.655-662.
[I 11 a) B. K Krebs. A. Miiller. H. H . Beyer. Incirg. Clicni. 1969.8.436-443: b)
B. K. Krebs. A. Miiller. H. H. Beyer. J Chern. Soc. Clirm. C(JmfnlLf7.1968.
263 --264.
[I21 a) H. H. Beyer. 0 . Glemser. B. K. Krebs. Angrir.. Chmi. 1968. 80, 286287: Angrii.. Cheni.In!. Ed Engl. 1968. 7. 295-296; b j H. W. Roesky. D.
Hesse. M. Noltemeyer. Errr. J SolidSmte Inorg. Clirm. 1991.28.809-814:
c) H. H Beyer. 0 . Glemser. B. K. Krebs. G . Wagner, Z. Anor'g. Chem.
1970. 376. 87 -100: d) J. W. Johnson. J. F. Brody. G . B. Ansell. S. Zentz,
Ac./if CrJ.s/u//ogr.Srcr. C 1984. 40, 2024- 2026.
[I31 M. Tobias. M Jansen. Angm. Clirni. 1986. 98. 994- 995; Angru.. Clieni.
In/. Ed. €fig/. 1986. 25. 993-994.
1141 W. A. Herrmann. F. E. Kuhn. R. W. Fischer. W. R. Thiel, C. C. Ramgo.
fnorg. Charn. 1992. 3f. 4431 -4432.
Catalysis of the Hydrolysis of
Phosphoric Acid Diesters by Lanthanide Ions
and the Influence of Ligands
By Hans-J6rg Schneider,* Jlirg Rammo,
and Ronald Hettich
Since Bamann discovered the catalytic effectiveness of lanthanide ions in the hydrolysis of glycerol phosphates,"] these
and transition metal ions have also been used as catalysts for
the cleavage of ribose phosphates, which are structurally
related through their vicinal hydroxy g r o u p ~ . [ ~The
- ~ ] hydrolysis of normal phosphoric acid esters or of DNA ( I )
requires much more drastic conditions than that of RNA (2)
due to the absence of the 2'-OH group. Considerable acceleration of the reactions can be achieved with more highly
charged transition metal ions.[', In particular, Chin et
R
'
1716
V C H ~ ~ ~ / ( ~ g s g ~ ~ . snihH.
e / / . r0-69451
~ / ~ ( ~ ~Wwn/i&ii,
i
1993
-o-t=o
-o-p=o
R
I(X=H)
2 ( X = OH)
3a ( R = H )
3b ( R = N 0 2 )
al.['blhave shown that with specific cobalt complexes even
nonactivated esters such as dimethyl phosphate react up to
10'' times faster."] However, it appears that the-sometimes not very stable-metal complexes are used up during
the reaction, that is they are not functioning as catalysts and
Michaelis- Menten kinetics (as found with enzymes) were
not observed. Recently Komiyama et aI.[*"I showed for the
[*] Prof. Dr. H.-J. Schneider. DiplLChem. J. Rammo,
Dipl.-Chem. R. Hettich
Fachrichtung Organische Chemie der Universitit
D-66041 Saarbrucken (FRG)
Telefax: Int. code + (681)302-4105
I**]
Suprainolecular Chemistry. Part 38. Part 37: H:J.
0. A. Raevsky. J Ofg. Clieni., in press.
0570-0833/93i1212-1716 S 10.01)+ .25:0
Schneider, V. Rudiger.
Angm'. Cheni. fnt. Ed. Enxi. 1993, 32. No. 12
first time that the cleavage of plasmid DNA could also be
accelerated by lanthanide ions. The conditions, however, are
so drastic, in comparison to those of well-known radical
D N A cleavage with redox metals,[8b1that the participation,
at least in part, of a radical mechanism cannot be excluded.
We report here on the highly efficient catalysis of the saponification of the phosphoric acid diary1 ester 3 by lanthanide
ions, characterized by saturation kinetics and "turnover", and
on the main possibilities of controlling the hydrolysis with
complex ligands. The most important factor in the potential
use of synthetic reagents for the hydrolysis of phosphoric
acid esters- -be they insecticides, chemical weapons, or nucleic acids- -is that the catalytic center is located in a kinetically stable complex. This should, for example, make it
possible to immobilize catalysts, to raise their affinity for
D N A (thus, for example, concentrations of drugs can be
reduced to levels suitable for therapy), and to selectively
cleave D N A strands (through the formation of a triple helix
containing oligonucleotide complex conjugation [91). This
was realized-- apart from a few exceptions['O1--largely with
o.uidu/iw/r. active reagents," 'I of which the iron -EDTA
oligonucleotides of Dervan et aI.["] are the best known. The
very reactive oxygen-containing radicals that are formed
have the disadvantage of not being very selective and of
producing unnatural cleavage products; this can be avoided
by the hydrolysis of phosphoric acid esters--as occurs in
nature.
Initially, we tried to use strong nucleophiles such as thiolates. oximates, etc. (thiophenol, salicylaldoxim, iodosobenzene) with the aim of accelerating the hydrolysis of model
phosphates such as 3b, since their affinity for D N A can be
raised almost without limit by combining such ligands with
polyamines.[' 3a1 After a preliminary test of this method with
plasmid D N A had Ied to hardly any detectable
we
measured, photometrically, the release of nitrophenolate
from the model ester 3 b in the presence of different concentrations of europium(I1r) chloride at p H 7.0. At [Eu3+]=
5x
M, for example, kobr= 1.67 x
s - ' was measured
which corresponds to an acceleration of k,,,/k, = 1.1 x lo8.[']
Under the same conditions Yb3+ gave kobs= 3.7 x
s - ' ; addition of PbZ+ salts produced cloudiness. All the
reactions were (pseudo)-first order with up to 95 % reaction
with a linear correlation coefficient of r>0.997; generally an
excess of catalyst was used. The measured final extinction
shows that hydrolysis under normal conditions ([3 b] <
[Eu3']) leads to the removal of both phenoxy groups. This
means that the corresponding monophenyl ester, as in noncatalyzed hydrolysis, reacts faster than the d i e ~ t e r . ~ ~ " ]
To ascertain that the catalyst retained its activity under
"turnover conditions", measurements were made with a tenfold excess of substrate. These could again be evaluated with
a first order kinetic equation. The observed rate of nitrophenolate release. kobs= 3.9 x
s - ' (50 "C, [Eu3+]=
1 x 1 0 - 4 ~ ) was
.
about half of that found with an excess of
[ E u 3 + ] ( k = 8.6 x
s-I). Here the monoester was
present at a much lower concentration than the starting material which released only one phenolate ion. In addition,
when [3]> [Eu3'], the concentration of active, free Eu3' is
reduced by binding to 3. The saturation kinetics (Fig. 1)
observed for the first time with Eu3+ yielded, by nonlinear
curve-fitting for a 1 : 1 complex, a Michaelis-Menten con~ order ofmagnitude ofthis is
stant of K M = 2.9 x 1 0 - 3 (the
in accord with the binding constants of lanthanide ions with
phosphates['41), and a catalytic constant of k,,, =
2.6 x
s - ' . The rate constant for hydrolysis without a
catalyst can be estimated from known data at 50"C[5d1as
k = 3x 10-'o~-'.
0
0
0.002
0.006
0.010
c(EuCI,) [MI -3
Fig. 1. Dependence of the kinetics of hydrolysis of bis(4-nitropheny1)phosphate 3 b ([3b] = 3 . 7 6 ~IO-'M) on catalyst concentration [Eu"] (in 0.01 M
EPPS buffer: 50.0 C , pH 7.00): experimental points and a simulated Michaelis- Menten curve.
Although the rate of hydrolysis of nitrophenyl esters can
be easily measured, the hydrolysis mechanism may be different from that of unactivated derivative^.^^, loa1
We have,
therefore, investigated the effectiveness of lanthanide ions in
the hydrolysis of the diphenylphosphate 3a. This ester is so
inert that the necessary constants for comparison of the hydrolysis at p H 7.0 are, as with d i m e t h y l p h ~ s p h a t e ,only
~~~~
obtainable by extrapolation from the correlations described
by Kirby et a1.['51Assuming that the activation entropy for
the hydrolysis in water is largely independent of the diester,'5b1an activation energy of about 30 kcalmol-' is obtained. The calculated rate constant would then be k , =
3.6 x lo-'' s - ' (at 70 "C). The observed value with [Eu3'] =
4.3 x 1 0 - 3 is
~ kohs= 3.95 x
which, with k,,,/k,z1O6
(at 7OCC),shows even a somewhat greater catalytic effect
than with the nitrophenyl ester 3 b (kOh,/k,= 0.56 x lo6,
50 "C).
The effect of ligands on the catalytic effect of the Eu3+ ion
was investigated with ligands 4-17 (Scheme 1) under the
same conditions. From reactions with D N A it is known that
with EDTA. for example, the metal effect may be completely
suppressed.[41With a series of nitrogen-containing ligands
(4-8) we d o indeed find a reduced rate of hydrolysis (see
Scheme 1). It can be estimated from known complexing cons t a n t ~ ~how
' ~ ] many "free", that is aqua-complexed, metal
ions are still available at each concentration. Comparison
with the values predicted from the saturation curve (Fig. 1)
shows that even when they are complexed the metal ions are
almost always still catalytically effective. In the presence of
most ligands the activity drops only to 10-50% of that of
the ligand-free solution, although with 8 and 9, for example,
only about one percent of "free" metal ion is present. The
two hydroxycarboxylic acids 16 and 17 are exceptions; here,
the residual activity is close to the detection limits. The Eu3+
complex with [2,2,2]cryptand (9) proved to be particularly
promising. In spite of its high complexation constant, this
was the only one that almost retained the activity of the free
metal ion. Even the cryptands form complexes with trivalent
lanthanide ions sufficiently fast under the measurement conditions,["] whereas their dissociation, for example a t 25 'C
with k , =
s-', is already relatively slow.['6' With their
thermodynamic and kinetic stability. coupled with the retention of their activity, the most important prerequisites for the
future use of such complexes are fulfilled.
In order to get closer to the typically high RNA rates of
hydrolysis by varying the ligands in the complexes, a new
concept was investigated. The generally accepted reason for
the high reactivity of R N A is the formation of the cyclic ester
cyclo-2 through the participation of the neighboring 2'-OH
-NH
H,N - ( C H 2 ) n
,
4a ( n = 2)
( C H C H0HC H2
0.17
5
A
)2N
A
N ( C H 2 C H 0 H C H 3) 2
0.62
7
0.49
N(CH,CH2CH,NH,),
NH
’
J
HN
i
this hypothesis (see Scheme 1). The advantage of such poly01s is that-as in RNA-they contain an additional vicinal
OH group next to the already phosphorylated OH group, so
that in a second (faster) step a cyclic phosphate analogous to
cyclo-2 can be formed. The observed effects enable an additional acceleration of catalysis by a factor of 2.5. More im-
4b ( n = 3 )
0.13
6
0.38
WN
HOOCCH,HN
8
A
0.082
( c = 0.005 M )
NHCH,COOH
portantly this acceleration is clearly dependent on the structure of the polyols; a minimum distance is obviously
required from the metal binding center to the OH group
which serves as a nucleophile towards the phosphate. In view
of the known small complexing constants of lanthanide ions
with polyhydroxy compounds containing vicinal OH
g r ~ u p s l ’ ~and
” ’ the resulting minimum concentration of active complex in water the observed accelerations are considerable: The addition of, for example, 5 x t O - 2 ~15 under
realistically observable conditions (with [Eu3’] = 5 x
1 0 - 3 ~ leads
)
to a total increase in the hydrolysis rate of
1.4 x 10’.
9
0.92
( c = 0.005 M )
R-0
R
-9
OH
Es,
OH
[oH
:
i H0
OH
1 Her:
11
1.16
10
1.03
Scheme 2. The mechanism of the hydrolysis of phosphoric acid diesters when
the OH group in RNA-derived substrates is replaced by the OH group from a
metal catalyst complex.
HO!:[
12
0.54
13
2.0
”
OH
OH
OH
OH
14
2.24
COOH
OH
15
2.53
16
0.0055
17
< 0.0012
Scheme 1. Complex ligands L and their effect o n the catalytic activity of Eu3 ;
the values show the ratio of the rate constants with and without additional
ligand ([3b] = 3 . 7 6 ~1 0 - 5 and
~
[L] = 5 x lo-”. With 8 and 9 [L] = 5 x
1 0 - 3 because
~
of their low solubilities). The following compounds were also
added but were unsuitable because of precipitation or clouding: spermine.
N,N’-bis(3-aminopropyl)piperazine,3.4-dihydroxyphenylalanine. m-hydroxybenzoic acid. 3,5-dihydroxybenzoic acid. pyrogallol.
+
group. In principle it should be possible to replace this group
with a nucleophile attached to a metal complex instead of to
the substrate (Scheme 2). The results of preliminary experiments with polyols, which bind-even though
with the catalytically effective metal ions and, in addition,
bear nucleophilic OH groups on their peripheries, support
CyClO-2
1718
i.,VCH Ver/u~.ge.\e//s~ltu/t
nihH, 0-69451 Wrmheitn. IYY3
In summary, it has been shown that 1 ) phosphoric acid
ester hydrolyses can be catalyzed with turnover and
Michaelis- Menton kinetics analogous to those observed for
enzymes by stable and readily available lanthanide complexes; even with only slightly activated leaving groups accelerations up to a factor of lo6 are possible. 2) the catalytic activity is retained even in thermodynamically and kinetically
very stable complexes so that it should be possible, through
modification of the ligands, to further raise their effectiveness and selectivity with respect to biopolymers such as
DNA, and 3) through the introduction of additional nucleophilic groups in the metal complexes, instead of the 2’-OH
groups which are available on the ribophosphates in the
substrate, a further raising of the catalytic activity is possible.“’]
Received: May 7, 1993
Revised version: July 24, 1993 [Z6064IE]
German version’ Anyew. Cliern. 1993, 105. 1773
111 a) E. Bamann, Angew. Client. 1939, 52, 186; b) E. Bamann, E. Nowotny.
Cliern. Ber. 1948, 81. 455; c) E. Bamann, F. Fischler. H. Trapmann,
Bioclimt. Z. 1951. 325. 413, and references therein.; d) see also: W. W.
Butcher, F. Westheimer. J. Am. Clzetn. Sot. 1955. 77. 2420.
[2] R. Breslow, D.-L. Huang, Pror. Nut/. Acud. Sci. USA 1991. 88, 4080.
[3] a) M. KOmiyamd, K. Matsurnura, Y. Matsumoto, J. Chrm. SOC.
Chem.
Commun. 1992, 640; b) Y. Matsumoto, M. Komiyama, ibid. 1990. 1050;
see also J. Sumaoka, M. Yashiro, M. Komiyama. ;bid 1992. 1707 (hydrol-
ysis of a cyclic phosphate).
[4] J. L. Morrow, L. A. Buttrey, V. M. Shelton, K. A. Berback. J. Ant. Cliem.
Soc. 1992, l f 4 , 1903. and references therein.
[S] a) 3. Chin, Acr. Clicm. Res. 1991. 24, 145, b) J. H. Kim, J. Chin, J. Am.
Chrni. Sor. 1992. 114.9792; c) K. A. Browne, T. C. Bruice, ibid. 1992, 114.
4951, and references therein.; d) J. Chin. M. Banaszczyk. V. Juhian, X.
Zou, ;hi(/.1989, I l l . 186, and references therein.
161 a) P. Hendry, A. M. Sargeson. Proy. ltiorg. Cltem. 1990,38,201: b) M. A .
DeRosch. W. C. Trogler, h o g . Clicm. 1990, 29. 2409; c) J. R. Morrow.
L. A. Buttrey. K. A. Berbdck, hid. 1992, 31. 16.
[71 For a better comparison of the efficiency of the systems referred to in the
literature we define: X,,, = X,,,,[catalyst]~I . With k,,, = l o 9 to 10”, only
0570-0833/Y3:1211-1718 3 10.00f .25:0
Angeir. Clteni. lnr. Ed. Engl. 1993, 32. No. 12
[XI
the (not catalytically effective) Co complexes of Chin et al. [ S b.d] are faster
than those presented here with k,-, = 10': complexes described earlier with
k,,, = 10' to 10" are considerably less reactive [6b.c].
a ) Y. MJtsumoto. M. Koyiyama. Nuckic Acids Si.nip. Ser. 1992. 77, 33: b)
P. Tachon. Frtv Rudicd Res. Conmiin. 1989. 7. 1 .
R e v i t s . N T. Thuong. C. Helene A i i g ~ i i .Chani. 1993 105. 697: Angeiv.
C/i(,m In!. ti/.Lngi. 1993, 33. 666, and references therein.
d ) L. A . Basilc. A. L. Raphael. J. K. Barton. J. Ain. Chein. Soc. 1987. 109.
7550: h ) concerning the lanthanide-ion-catalyzedhydrolysis of a phosphoric acid triester (which eenerally react faster than the DNA analogous
phosphoric acid diesters [Sal) see: R. W. Hay. N . Govan. J Chern. Sot..
C(n~itiriitt1990. 714.
D. S Sigman. Biochriii~.\rri~1990. 39, 9097; D. S. Sigman. C. B. Chen,
A i m / Rrv Biodi~wi.1990. 59. 207; C. J. Burrows. J. G. Muller. X. Chen,
A. C'. Dildir. S. E. Rokita. Purr A/Jp/. Chui?.1993.65. 545 (Ni complexes):
B Meunier. Chi~iii.Riw. 1992. 97. 1411 (porphyrins).
a ) R P. Hertzberg. P. B Dervan. J. ,4117. Clrcwi. Sot,.1982. 104. 313; for
must recent applications see for example W. S. Wade. M. Mrksich. P. B.
Deiniin. ihid. 1992. 114. 8783; b)see also X. Chen. S . E. Rokita. C. J.
Buri-oas. h i d . 1991. 113. 5884: N. Gupta. N. Grover. G. A. Neyhart, P.
Singh. H. H. Thorp. fnorg. C/icwi. 1993. 32. 310; J. R. Morrow. K. A.
.
Acro 1992, IY5. 245. and references therein.
Kolosaa. h w ~C'hiiii.
a ) Cl'. H -J. Schneider. T Blatter. Atigeii C%rrn.1992. i(J4. 1244. A n g i w
C/imi. h i . € I / . Etigi. 1992. 31. 1207. and references therein.: b) H.-J.
Schneider, J. Rammo. A . E. Eliseev. B. Schu. unpublished results.
a ) Gi~iii/in,Hoiidhook o/ Inorgunrc C/ieiiii.s/rj~1980.. 8th edition. Purr D1
1980. p. 159 ff. Purr 0 3 . 1982, p. 314 ff Purl 03. 1981, p. 31 ff; b) G.-y.
Ad'ichi. Y Hirashima in Corion Bindrng hi, Mutrocrclt..~(Eds.: Y. Inoue. G.
W. (joke]). Dekker. New York. 1990. p. 701 (lanthanoid complexes); c) €5.
M. Eyrinp. S. Petrucci. ihid. p. 179 (the discrepanciesin the kinetic parametcrs. due to the meiisureinent technique. discussed here and iilso. in part.
sometimes different. cornplexing constants [14a.b.d] are of lesser importance for our interpretation): d ) F. Vogtle, E. Weber in Cloii.ti Niers and
Atro/o,v.s (Eds. S. Patai. Z. Rappoportj. Wiley. Chichester. England 1989,
p. 216 fT.
A. .IKirby. M . Younas. J. C/ietii. Soc. B 1970. 510.
E 1.. Lee. 0. A . Gansow. M. J. Webei, J. Am. Ciien?.Sot. 1980. l f l .2275:
from the data given here i t turns out that for Eu3+ [2.2,2]cryptand (9)
a t 1 5 C for the association under the conditions used by us a half-life of
about 80 s was obtained. For this. as probably also for the even higher
catalytic activity of the complex, i t is important that some hydrated metal
ion9 can F t i l l e x i ~ even
t
inside the cryptands [14c.d].
The reaction rates were measured photometrically at 400 nm (3b) and
275 nni (3a) (50 C: pH 7.0; buffer: 0.01 M EPPS): other conditions are
givc.ii in the legends to Figure I and Scheme 1 . The nonlinear curve-fitting
for (pseudo)-first order reactions, usually over two or three half-life times,
had excellent correlation coefficients ( > 0 997). The observed spread of the
ireilction rate constants obtained from the regression wds 5 1 %; the same
sprrnd was observed in duplicate runs.
'
+
Palladium-Catalyzed Enantioselective
Bis-alkoxycarbonylation of Olefins""
peroxide.[51Complexes of the type [PdL,X,] with modified
ligands have not been used for this reaction, despite their
catalytic activity in many other carbonylation reactions.'' - 9 1
When styrene is the substrate and either [ (1, I O-phenanthroline)Pd(p-CH,C,H,SO,),I
or [(1,2-bipyridine)Pd(CF,COO),] is employed as the catalyst precursor. poly(1-oxo-2-phenyltrimethylene) is formed. It was recognized
that when the reaction is conducted in methanol some of the
macromolecules formed contain two terminal methoxycarbony1 groups (Scheme l).'''] Oligorners (Scheme 1, n = 1. 2
up to 10) were obtained by increasing the amount of the
oxidant.I"I When the catalyst precursor had diphosphane
ligands, mainly saturated monoesters and cc,P-unsaturated
esters were observed ; however, some succinate was formed
as well.'' The syn stereochemistry of the dicarbonylation
reaction products["] prompted us to attempt enantioselective bis-methoxycarbonylation to give optically active succinates.["'
Scheme 1
When the previously reported complex [Pd((R,R)~ ~ O ~ ) ( O , C C F , ) , ](diop
~ ' ~ ~= 3,4-bis[ (dipheny1phosphino)methyI]-(2,2-dimethyl-1,3-dioxolane)was used as the m t a lyst precursor in the presence of Sn(O,SCF,), , (!?)-dimethyl
phenylsuccinate could in fact be isolated in 29% yield and
with 30% ee. Similar results were obtained with an "in situ"
system composed of [Pd(acac),], (R,R)-diop, and two equivalents of trifiuoroacetic or para-toluenesulfonic acid. With a
similar "in situ" system, in which (R)-N,N-dimethyl-I-[(S)1 ',2-bis(diphenylphosphino)ferrocenyl]ethylamine served as
the chiral ligand, comparable results ( < 2 9 % re) were obtained. Analogously, dimethyl propylsuccinate was obtained
with 17% ee1131and 4 % yield from the bis-methoxycarbonylation of 1 -pentene with the diop-containing catalytic
system.
The excellent stereochemical control achieved in the copolymerization of propene with carbon monoxide''" 14*
(Scheme 1, R = CH,) by using atropoisomeric diphosphanes prompted us to test this type of ligand (Scheme 2 ) for
the enantioselective bis-methoxycarbonylation.
By SIh,iu C. A . Nefkens, Martin Sperrle,
and Gimnhatiisra Consiglio*
The bis-alkoxycarbonylation of olefins to give succinates
as the products (Scheme I , n = I ) is generally carried out
with PdCI, in the presence of hydrogen acceptors."] Succinates have been prepared with high selectivities from various
olefins by using CuCI, in the presence of sodium butyrate.E21
Other suitable catalyst systems for this reaction include PdC1, in combination with butyl nitrite,[31 Pd(OAc), in the
presence of benzoquinone and oxygen,[41and [Pd(acac),]
(Hacac = 2,4-pentanedione) in the presence of di-tert-butyl
[*] Prof. Dr G . Consiglio. Dr. S. C. A. Nefkens. Dip1:Chem.
[**I
M. Sperrle
Eidgcniissische Technische Hochschule
Lahoriitorium fur Technische Chemie. ETH-Zentrum
Universitiitsstrasse 6. CH-8092 Zurich (Switzerland)
Telefkx: Int. code + (11262-1746
This research was supported by the Schweizerischrn Nationalfonds zur
Fiirdei-uiig der wissenschaftlichen Forschung. We thank Hoffmdnn-La
Roche AG (Dr. E. Broger) for the generous gift of the ligands 1 and 2.
1
2
3
Scheme 2.
In a series of bis-methoxycarbonylations of styrene using
the "in situ" system [Pd(acac),]/L - L/p-CH ,C,H4S0,H
(1 : 1 :2 mol ratio) the chiral diphosphane hgand (L - L) was
varied. We found that the optical purity of the dimethyl
phenykuccinate obtained could be improved to 82-93 % by
employing the optically pure atropisomeric ligands 1-3
(Table I). A maximum of 93% ee was obtained with
2,2'-dimethoxy-6,6'-bis(diphenylphosphino)biphenyl2 (biphemp-OMe) as the ligand. The yield with respect to the
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