Rapid, selective ru-sulfonate-catalyzed allylation of indoles using alcohols as substrates

Article abstract of DOI:10.1021/om900168y

The Ru-catalyzed allylation of differing indole compounds using ArCH(OH)CH d CH₂ (Ar) Ph, 2-CH₃C₆H₄, 2-CH ₃OC₆H₄ 2-ClC₆H₄, and 1-naphthyl) is relatively fas

Full text of DOI:10.1021/om900168y

Organometallics 2009, 28, 3437–3448
3437
Rapid, Selective Ru-Sulfonate-Catalyzed Allylation of Indoles Using
Alcohols as Substrates
Stefan Gruber, Alexey B. Zaitsev, Michael Wo¨rle, and Paul S. Pregosin*
Laboratory of Inorganic Chemistry, ETHZ, Ho¨nggerberg, CH-8093 Zu¨rich, Switzerland
Luis F. Veiros
Centro de Qu´ımica Estrutural, Complexo I, Instituto Superior Te´cnico, AVenida RoVisco Pais 1,
1049-001 Lisbon, Portugal
ReceiVed March 3, 2009
The Ru-catalyzed allylation of differing indole compounds using ArCH(OH)CHdCH2 (Ar ) Ph,
2-CH3C6H4, 2-CH3OC6H4 2-ClC6H4, and 1-naphthyl) is relatively fast (usually <30 min for 100%
conversion) at ambient temperature in the presence of [Ru(Cp*)(CH3CN)3](PF6) + a sulfonic acid
cocatalyst, RSO3H (R ) p-tolyl, a camphor fragment or CH3). The new catalysts allow allyl alcohols
rather than carbonates, halides, acetates, etc., to be used as substrates in this allylation chemistry, thereby
avoiding the use of a (wasted) leaving group. The branched products are favored, and in a number of
examples b/l ratios in excess of 20 are observed. The catalyst is selective in that there is little or no
N-allylation. The use of acids such as CF3SO3H or HBF4 results in slower and/or less selective reactions.
Although phosphoric acid additives show some promise, carboxylic acids are much less effective or do
not catalyze the reaction at all. The preformed isolated complexes [Ru(Cp*)(η3-C3H5)(RSO3)2] are efficient
catalyst precursors; however, NMR experiments suggest that one of the active species is the monosulfonate
cationic complex [Ru(Cp*)(η3-C3H5)(CH3CN)(RSO3)]+. Stoichiometric oxidative addition reactions are
shown to be relatively rapid. New Ru(Cp*) complexes have been generated and characterized by NMR
methods. DFT calculations suggest that the large b/l ratios observed have a structural basis in that the
Ru-C(allyl) bond length for the substituted terminal allyl carbon, Ru-C(1), is relatively long. X-ray
structures for Ru(Cp*)(η3-C3H5)(SO4) and the dication [Ru(Cp*)(η3-C3H5)(H2O)2]2+ (as a camphor
sulfonate salt) are reported.
derives from orbital control12 and that the reaction times can
be markedly reduced by using a more labile, smaller coordina-
tion sphere.13 Further, several of our new Ru(IV) catalysts allow
allyl alcohols rather than carbonates, halides, acetates, etc., to
be used as substrates in this allylation chemistry.14 This avoids
Introduction
Ruthenium catalysts are finding increasing applications in
both the routine and enantioselective synthesis of organic
compounds.1-3 Specifically, there has been a renewed interest
in applying Ru(Cp or Cp*)-based catalysts in allylic alkylation,
amination, and phenolation chemistry,4-11 as several of the Ru
complexes are capable of preferentially producing branched
(rather than linear) allyl-organic products. Scheme 1 shows a
selection of the Ru catalysts currently in use.
(6) (a) Zhang, S.; Mitsudo, T.; Kondo, T.; Watanabe, Y. J. Organomet.
Chem. 1993, 450, 197–207. (b) Kondo, T.; Kodoi, K.; Nishinaga, E.; Okada,
T.; Morisaki, Y.; Watanabe, Y.; Mitsudo, T. J. Am. Chem. Soc. 1998, 120,
5587–5588. (c) Morisaki, Y.; Kondo, T.; Mitsudo, T. Organometallics 1999,
18, 4742–4746. (d) Morisaki, Y.; Kondo, T.; Mitsudo, T. A. Organometallics
1999, 18, 4742–4746. (e) Kondo, T.; Morisaki, Y.; Uenoyama, S.; Wada,
K.; Mitsudo, T. J. Am. Chem. Soc. 1999, 121, 8657–8658. (f) Matsushima,
Y.; Onitsuka, K.; Kondo, T.; Mitsudo, T.; Takahashi, S. J. Am. Chem. Soc.
2001, 123, 10405–10406. (g) Kondo, H.; Kageyama, A.; Yamaguchi, Y.;
Haga, M.; Kirchner, K.; Nagashima, H. Bull. Chem. Soc. Jpn. 2001, 74,
1927–1937. (h) Nagashima, H.; Kondo, H.; Hayashida, T.; Yamaguchi, Y.;
Gondo, M.; Masuda, S.; Miyazaki, K.; Matsubara, K.; Kirchner, K. Coord.
Chem. ReV. 2003, 245, 177–190.
(7) (a) Tanaka, S.; Saburi, H.; Kitamura, M. AdV. Synth. Catal. 2006,
348, 375–378. (b) Saburi, H.; Tanaka, S.; Kitamura, M. Angew. Chem.,
Int. Ed. 2005, 44, 1730–1732.
(8) Onitsuka, K.; Okuda, H.; Sasai, H. Angew. Chem., Int. Ed. 2008,
47, 1454–1457.
(9) (a) Hermatschweiler, R.; Fernandez, I.; Breher, F.; Pregosin, P. S.;
Veiros, L. F.; Calhorda, M. J. Angew. Chem., Int. Ed. 2005, 44, 4397–
4400. (b) Fernandez, I.; Hermatschweiler, R.; Pregosin, P. S.; Albinati, A.;
Rizzato, S. Organometallics 2006, 25, 323–330.
(10) Onodera, G.; Imajima, H.; Yamanashi, M.; Nishibayashi, Y.; Hidai,
M.; Uemura, S. Organometallics 2004, 23, 5841–5848.
In a series of reports we have recently suggested that the
regioselectivity of the Ru(Cp*)-catalyzed allylation reactions
* Corresponding author. E-mail: pregosin@inorg.chem.ethz.ch.
(1) Trost, B. M.; Rudd, M. T. J. Am. Chem. Soc. 2005, 127, 4763–
4776. (b) Trost, B. M.; Rudd, M. T. Org. Lett. 2003, 5, 1467–1470. (c)
Trost, B. M.; Fraisse, P. L.; Ball, Z. T. Angew. Chem., Int. Ed. 2002, 41,
1059–1061. (d) Trost, B. M.; Rudd, M. T. J. Am. Chem. Soc. 2001, 123,
8862–8863.
(2) (a) Bruneau, C.; Dixneuf, P. H. Angew. Chem., Int. Ed. 2006, 45,
2176–2203. (b) Le Notre, J.; Touzani, R.; Lavastre, O.; Bruneau, C.;
Dixneuf, P. H. AdV. Synth. Catal. 2005, 347, 783–791.
(3) (a) Grubbs, R. H. AdV. Synth. Catal. 2007, 349, 34–40. (b) Grubbs,
R. H. AdV. Synth. Catal 2007, 349, 23–24.
(4) Burger, E. C.; Tunge, J. A. Org. Lett. 2004, 6, 2603–2605.
(5) (a) Renaud, J. L.; Demerseman, B.; Mbaye, M. D.; Bruneau, C. Curr.
Org. Chem. 2006, 10, 115–133. (b) Le Paih, J.; Derien, S.; Demerseman,
B.; Bruneau, C.; Dixneuf, P. H.; Toupet, L.; Dazinger, G.; Kirchner, K.
Chem.sEur. J. 2005, 11, 1312. (c) Bruneau, C. Top. Organomet. Chem.
2004, 11, 125. (d) Derien, S.; Dixneuf, P. H. J. Organomet. Chem. 2004,
689, 1382–1065. (e) Mbaye, M. D.; Demerseman, B.; Renaud, J. L.; Toupet,
L.; Bruneau, C. Angew. Chem., Int. Ed. 2003, 42, 5066–5068. (f) Renaud,
J. L.; Bruneau, C.; Demerseman, B. Synlett 2003, 408–410.
(11) Demerseman, B.; Renaud, J. L.; Toupet, L.; Hubert, C.; Bruneau,
C. Eur. J. Inorg. Chem. 2006, 137, 1–1380.
(12) Hermatschweiler, R.; Fernandez, I.; Pregosin, P. S.; Watson, E. J.;
Albinati, A.; Rizzato, S.; Veiros, L. F.; Calhorda, M. J. Organometallics
2005, 24, 1809–1812.
10.1021/om900168y CCC: $40.75
2009 American Chemical Society
Publication on Web 05/28/2009

3438 Organometallics, Vol. 28, No. 12, 2009
Gruber et al.
Scheme 1. Ruthenium Allylation Catalysts
Scheme 2
fastest catalyst consists of [Ru(Cp*)(CH3CN)3](PF6), 1, together
with one of the sulfonic acids 3-5.
Equation 1 shows the Ru-catalyzed allylation of a number
of differing indole compounds using PhCH(OH)CHdCH2
wasting the leaving group and simplifies the workup, as water
is now the side-product.
We report here an extension of our previous study on the
allylation of indole derivatives with CH2dCHCH2OH. We
emphasize that our catalytic system works rapidly at ambient
temperature; this is pertinent since, according to the literature,
many allylation reactions are fairly slow,5e,f,7b,8,10,15-17 requiring
a number of hours and occasionally elevated temperatures. In
a second section we describe the synthesis and characterization
of new RuCp* complexes and suggest how these are related to
our catalytic reactions.
(rather than CH2dCHCH2OH14c) as substrate, and Table 1
summarizes the relative rates (for 100% conversion to products)
and the observed regioselectivity. These indole derivatives
undergo fast allylation (usually <30 min for 100% conversion)
at ambient temperature in the presence of 1 + sulfonic acid 4
as catalyst. The branched products are favored, and the catalyst
is selective in that we do not find either N-allylation or diallyl
ether products. As noted previously,14a,c electron-withdrawing
substituents in the 5-position of the indole slow the reaction
considerably.18 From entries 6 and 9 it is clear that the catalyst
is also active in allylation of N-substituted indoles. These
experiments show that it is not necessary to add a base in order
to deprotonate the nucleophile (as is common in many Pd-
catalyzed allylation reactions) in order to form a more nucleo-
philic anion.
Results and Discussion
Reactions of PhCH(OH)CHdCH2 with Several Indole
Compounds. Scheme 2 gives the Ru-salts and acid cocatalysts
used in this study. Earlier13,14c we described the dicationic
catalyst [Ru(Cp*)(η3-C3H5)(CH3CN)2]](PF6)2, 2, and demon-
strated that this complex can release one proton when attacked
by a nucleophile. This proton, together with [Ru(Cp*)-
(CH3CN)3](PF6), 1, generated when the indole nucleophile
attacks the complexed allyl ligand, helps to convert the alcohol
into a substrate with a good leaving group. Currently,14a our
(13) (a) Hermatschweiler, R.; Fernandez, I.; Pregosin, P. S.; Breher, F.
Organometallics 2006, 25, 1440–1447. (b) Fernandez, I.; Hermatschweiler,
R.; Breher, F.; Pregosin, P. S.; Veiros, L. F.; Calhorda, M. J. Angew. Chem.,
Int. Ed. 2006, 45, 1–6.
(14) (a) Zaitsev, A. B.; Gruber, S.; Pluss, P. A.; Pregosin, P. S.; Veiros,
L. F.; Worle, M. J. Am. Chem. Soc. 2008, 130, 11604–11606. The table of
catalytic data from this work (Allylation of indole by different allyl alcohols
catalyzed by the 1 + 4 system) is given as Table S1. (b) Gruber, S.; Zaitsev,
A. B.; Worle, M.; Pregosin, P. S.; Veiros, L. F. Oranometallics 2008, 27,
3796–3805. (c) Zaitsev, A. B.; Gruber, S.; Pregosin, P. S. Chem. Commun.
2007, 4692–4693. (d) Nieves, I. F.; Schott, D.; Gruber, S.; Pregosin, P. S.
HelV. Chim. Acta 2007, 90, 271–276.
Data for the allylation of several indole compounds with the
sterically hindered allyl alcohols 6a and 7 are given in Table 2.
The increased bulkiness of the aryl substituent (a) significantly
improves the observed branched-to-linear (b/l) ratio from ca.
7-10 (Table 1) to ca. 40-60 and (b) leads to somewhat faster
reactions. However, as indicated by entries 4 and 9, a phenyl
substituent at the 2-position of the indole results in much more
linear product.
(15) Oi, S.; Tanaka, Y.; Inoue, Y. Organometallics 2006, 25, 2773–
2377.
(16) Yamamoto, Y.; Nakagai, Y.; Itoh, K. Chem.sEur. J. 2004, 10,
231–236.
Catalysis with Differing Acid Sources. Although it is clear
that the added acid contributes to making water the leaving
(17) Zhang, H. J.; Demersernan, B.; Toupet, L.; Xi, Z. F.; Bruneau, C.
AdV. Synth. Catal. 2008, 350, 1601–1609. (b) Mbaye, M. D.; Demerseman,
B.; Renaud, J. L.; Bruneau, C. J. Organomet. Chem. 2005, 690, 2149–
2158.
(18) Electron-withdrawing substituents in the indole slow the reaction.
Specifically, the reaction of PhCH(OH)CHdCH2 with 5-cyano indole
achieves 100% conversion only after 24 h.

Ru-Sulfonate-Catalyzed Allylation of Indoles
Organometallics, Vol. 28, No. 12, 2009 3439
Table 1. Allylation of Indoles with PhCH(OH)CHdCH2 Catalyzed
by 1 + 4a
slower than when 3-5 were employed, 1,1′- binaphthyl-2,2′-
diyl hydrogenphosphate (see Scheme 3) seemed promising.
Since this phosphoric acid derivative is not very soluble in
acetonitrile,20 the reactions were carried out by adding small
amounts of either dimethylformamide or water to dissolve the
acid (see Experimental Part). The results from these catalytic
experiments are given in Table 4. Although the reactions are
somewhat slower than with the sulfonic acids, entry 3 (with
the bulky 1-naphthyl group) and entry 10 are notable for their
excellent b/l ratios.
Since the sulfonic acids 3-5 represent the best cocatalysts
(and taking a hint from the result for the 1-naphthyl experiment
just mentioned), indole was allowed to react with the more
sterically hindered alcohol substrates 6a-c (see Table 5). The
reaction rates are comparable to those found for 3-5 in Table
3; however, in many runs markedly increased b/l ratios (often
Table 2. Allylation of Indoles with Two Bulky Aromatic Allyl
Alcohols Catalyzed by 1 + 4a
a Reaction conditions: CD3CN (0.5 mL), indole (0.07 mM), allyl
alcohol (0.07 mM),
1
(0.0035 mM), acid (0.0035 mM),
(1S)-(+)-10-camphorsulfonic. b Time for 100% conversion at room
temperature. c Small impurity of cinnamic alcohol. dThe signals of the
linear product could not be seen under the signals of the methyl group.
group in the oxidative addition step, the exact source of the
varying b/l ratios remains uncertain. To clarify this point, we
studied the influence of different acids on the rate and regiose-
lectivity of the allylation of eq 2 (see Table 3).
The sulfonic acids 3-5 (together with 1) each afford rapid
reactions and favorable b/l ratios. Triflic acid, CF3SO3H
(which does not usually replace CH3CN in the Ru-coordina-
tion sphere19), induces a rapid allylation reaction but is less
selective, and HBF4 is both slower and less selective.
Carboxylic acids are poor cocatalysts. Although not shown
in the Table, there is no reaction after ca. 25 min using either
acetic acid or p-nitro benzoic acid. Further, quinoline-8-
sulfonic acid, 8, in combination with 1 did not catalyze
allylation of indole with PhCH(OH)CHdCH2.20 In the
absence of acid (i.e., only 1 as catalyst), there is no
conversion at all.
a Reaction conditions: CD3CN (0.5 mL), indole (0.07 mM), allyl
Continuing, several phosphoric acids were tested and, indeed,
these afforded products. Although all of these reactions are
alcohol (0.07 mM),
1 (0.0035 mM), acid (0.0035 mM), room
temperature. b For 100% conversion.

3440 Organometallics, Vol. 28, No. 12, 2009
Gruber et al.
Table 3. Effect of the Acid on the Allylation of Indole with
Catalysis Using Isolated Complexes. Given the varying rates
and observed b/l ratios as a function of the acid in the catalytic
reactions, it seemed that the sulfonate anion is involved in the
ruthenium coordination sphere. Although we were not able to
obtain evidence for the existence of sulfonate complexes from
the catalytic solutions,21 several stoichiometric reactions in
acetonitrile/toluene solvent mixtures led to isolable sulfonate
complexes (see Scheme 4). The p-toluene14a and methyl
sulfonate bis-complexes, 10 and 11, were each obtained in ca.
69% yield. We were not able to obtain an analogous product
with camphor sulfonic acid; however, after more than one month
at ambient temperature crystals of the bis-aquo complex, 12,
were obtained from an acetone solution layered with ether. We
presume that the water stems from the acetone solvent.
Table 6 shows the catalytic data stemming from reactions
using isolated Ru(IV) catalysts 10 and 11 (without added acid)
and confirms that the presence of the complexed sulfonate anion
has a strong positive effect on the observed b/l ratios. The table
also gives data for our previously14c reported Ru(IV) catalyst
[Ru(Cp*)(η3-C3H5)(CH3CN)2]2+, 2, without the complexed
sulfonate (see entries 3 and 6). Clearly, in terms of both the b/l
ratios and the reaction rate, 10 and 11 are far superior.
PhCH(OH)CHdCH2
run
acid
time
3 h
convn, %
b/l ratio
1
no acid
0
2a
3a
4a
5a
6a
7a
8aa
8bb
3
4
5
40 min
25 min
30 min
32 min
50 min
80 min
60 min
5 h
100
100
100
100
<50
100
ca. 18
100
6:1
9:1
8.4:1
ca. 1:1
ca. 1:3
4.5:1
ca. 0.7:1
9.8:1
CF3SO3H
HBF4 · Et2O
H2SO4
H3PO4
1,1′-binaphthyl-2,2′-diyl
hydrogen phosphate
1,1′-binaphthyl-2,2′-diyl
hydrogen phosphate
P(dO)(OH)
8cc
8db
8ec
4 h
6 h
4 h
100
100
100
5:1
7.2:1
3.2:1
(p-OC6H4p-NO2)2
P(dO)(OH)
(p-OC6H4p-NO2)2
CF3CO2H
HO2CCO2H
9a
20 h
20 h
45
28
8:1
3.9:1
10a
a Reaction conditions: CD3CN (0.5 mL), indole (0.07 mM), allyl
alcohol (0.07 mM),
1 (0.0035 mM), acid (0.0035 mM), room
temperature. b CD3CN (0.48 mL), indole (0.09 mM), allyl alcohol (0.09
mM), Trost cat. (0.0046 mM), acid (0.0046 mM) in DMF-d7 (0.02 mL),
room temperature. c CD3CN (0.4 mL), D2O (0.1 mL), indole (0.09 mM),
allyl alcohol (0.09 mM), 1 (0.0046 mM), acid (0.0046 mM), room
temperature.
Given the activity of sulfuric acid as a cocatalyst (see entry
7 of Table 3), we have prepared the new Ru(IV) sulfate complex
13 (vide infra) and tested this, and Ru(IV) salts 14 and 15,
reported earlier, in the allylation chemisty of eq 2 (but without
additional acid). Only 15 showed some activity (42% conversion
after 5 h, b/l ) 3.4:1). It would seem that filling up two
coordination positions (with chelating sulfate, acetate, or
nitrogen ligands5e,f) has a detrimental effect on the allylation
rate.
>40:1) are observed. Entry 4 in the table shows that changing
the aryl sulfonic acid from 3 to the mesityl analogue 9 can be
advantageous with respect to the observed regioselectivity.
NMR Measurements. Although the catalytic results are
informative, there is still the question of the number of
complexed sulfonate ligands in acetonitrile solution. To shed
light on this question, we have carried out a series of NMR
measurements. Immediately after dissolving the bis-sulfonate
complex 10 (2 mmol/L) in CD3CN, one can observe a set of
1H NMR signals that can be assigned to a species formed by
dissociation of one p-toluene sulfonate ligand. The 1H NMR of
this freshly prepared CD3CN solution revealed five nonequiva-
lent η3-C3H5 allyl resonances (δ ) 6.13, 4.60, 4.43, 3.27, and
Summarizing, (a) the catalyst mixture consisting of 1 and a
sulfonic acid provides a fast and efficient method of introducing
allyl substituents at the 3-position of indole compounds using
alcohols as substrates, (b) not all acids are effective cocatalysts,
and (c) for the more sterically hindered alcohol substrates, the
observed regioselectivities are excellent. The ease with which
alcohols can be employed certainly makes these catalytic
reactions “atom economical”.
Scheme 3. Allylation of Indole with Several Aromatic Allyl Alcohols Catalyzed by
Hydrogenphosphate
1 and 1,1′-Binaphthyl-2,2′-diyl

Ru-Sulfonate-Catalyzed Allylation of Indoles
Organometallics, Vol. 28, No. 12, 2009 3441
Table 4. Allylation of Indole Using Aromatic Allyl Alcohols
Catalyzed by 1 and 1,1′-Binaphthyl-2,2′-diyl Hydrogenphosphate
Table 5. Catalysis with Sulfonic Acid Co-catalysts and Bulky
Alcohol Substrates
sulfonic
acid
reaction
timeb
b/l
ratio
run
X
1
2
3
4
5
6
7
8
9
Me
Me
Me
Me
OMe
OMe
OMe
Cl
3
4
5
9c
3
4
5
3
4
5
18 min
20 min
25 min
20 min
26 min
55 min
29 min
21 min
20 min
18 min
16:1
49:1
77:1
39:1
9:1
24:1
19:1
22:1
24:1
20:1
Cl
Cl
10
a Reaction conditions: CD3CN (0.5 mL), indole (0.07 mM), allyl
alcohol (0.07 mM),
1 (0.0035 mM), acid (0.0035 mM), room
temperature. b For 100% conversion. c Mesityl analogue of 3.
sulfonate methyl groups (D ) 16.91 × 10-10 m2 s-1 for the
signal at δ ) 2.36 and D ) 13.16 × 10-10 m2 s-1, for the signal
at δ ) 2.40). The latter value is identical to the diffusion
constant derived from the Cp* methyl groups at δ )1.67 (D )
13.08 × 10-10 m2 s-1), suggesting that these two ligands are
attached to same Ru atom. On the basis of these data we assign
the sulfonate moiety with the larger D-value to an uncomplexed
anion, and the sulfonate group with smaller D-value to a
coordinated p-toluene sulfonate ligand. The intensity of the
uncomplexed methyl signal at δ ) 2.36 slowly increases in time,
over hours, with concomitant decrease in the intensity of the
signal of the coordinated sulfonate at δ ) 2.40. At the same
time a new set of three η3-allyl resonances signals grow in (in
the ratio 2:2:1). On the basis of these observations, we propose
the sequence shown in eq 3. Consequently, given that the
catalytic reactions are rapid, we assume that the monosulfonate
cation is likely to be catalytically relevant. A mechanism for
the formation of the branched allyl product, consistent with all
of these observations, is given in Scheme 5.
a CD3CN (0.4 mL), D2O (0.1 mL), indole (0.09 mM), allyl alcohol
(0.09 mM), 1 (0.0046 mM), acid (0.0046 mM), room temperature.
b CD3CN (0.48 mL), indole (0.09 mM), allyl alcohol (0.09 mM), 1
(0.0046 mM), acid (0.0046 mM) in DMF-d7 (0.02 mL), room
temperature.
2.82) plus resonances for two separate p-toluene sulfonate
methyl groups (δ ) 2.40 and 2.36), in addition to a singlet for
the five equivalent Cp* methyl groups (δ )1.67). Pulsed
gradient spin-echo (PGSE) diffusion measurements22-26 gave
different diffusion constants (D values) for the two p-toluene
Oxidative Addition to Form the Ru(IV) Allyl
Complexes. A mixture of 1 equiv of 1, CH2dCHCH2OH,
and acid 4 led to fast (e7 min) formation of an η3-C3H5 allyl
Ru complex. A similar observation was made for an
analogous mixture containing PhCH(OH)CHdCH2 (see eq
4). Further, rapid formation of a Ru(IV) allyl complex
(19) Lackner, W.; Standfest-Hauser, C. M.; Mereiter, K.; Schmid, R.;
Kirchner, K. Inorg. Chem Acta 2004, 357, 2721–2727.
(20) The acid was not soluble in CD3CN. Addition of D2O (ca. 20% by
weight) led to solution of the acid.
(21) However, see: Shusuke, N.; Takuya, K.; Nozaki, K. Organome-
tallics 2009, 28, 656–658, for an example of a nickel catalyst containing a
chelating sulfonate ligand that is catalytically active.
(23) Zuccaccia, C.; Stahl, N. G.; Macchioni, A.; Chen, M. C.; Roberts,
J. A.; Marks, T. J. J. Am. Chem. Soc. 2004, 126, 1448–1464. (b) Zuccaccia,
D.; Macchioni, A. Organometallics 2005, 24, 3476–3486.
(24) (a) Pregosin, P. S.; Kumar, P. G. A.; Fernandez, I. Chem. ReV.
2005, 105, 2977–2998. (b) Pregosin, P. S. Prog. Nucl. Magn. Reson.
Spectrosc. 2006, 49, 261–288.
(22) Stilbs, P. Prog. NMR Spectrosc. 1987, 19, 1.

3442 Organometallics, Vol. 28, No. 12, 2009
Gruber et al.
was also observed on allowing 1 equiv each of 1,
PhCH(OH)CHdCH2, and methane sulfonic acid, 5, to react
in CD3CN solution. The new product in this case (see eq 5)
is assigned to an equilibrium mixture of the two Ru(IV)
species shown, on the basis of PGSE diffusion measurements.
The observed D-value for the sulfonate methyl group found
at δ ) 2.58 (14.92 × 1010, m2 s-1) is larger than that for the
Cp* methyl groups (11.76 × 10-10, m2 s-1), but smaller than
the D-value found for a solution of the model triethyl
(OH)CHdCH2 was evaporated and the resulting crude solid
suspended27 in CD2Cl2. The major product in solution is now
the monosulfonate complex [Ru(Cp*)(η3-2-CH3C6H4CHCH-
CH2)(CH3CN)(p-CH3C6H4SO3)]+, and 1H, 13C, and NOE NMR
details for this species are given at the bottom of Scheme 6.
In a further attempt to characterize Ru(IV)-monosulfonate
complexes, we have allowed 1 equiv of 1 to react with 1 equiv
of either CH3S(O)2OCH2CHdCH2 or p-CH3C6H4S(O)2OCH2-
CHdCH2 at ambient temperature, first in CD3CN and then in a
separate experiment for each substrate, in CD2Cl2 solution in
an NMR tube. Scheme 7 shows a partial summary of the data
from these NMR experiments.28 In both cases, oxidative addition
reactions proceed rapidly. In CD3CN, the major product is the
known28 Ru(Cp*)(η3-allyl)(bis-nitrile) dication; however there
are several minor products, and we assign one of these to Ru(Cp*)-
(η3-C3H5)(CH3CN)(p-CH3C6H4SO3)+ and Ru(Cp*)(η3-C3H5)-
(CH3CN)(CH3SO3)+, respectively. In CD2Cl2, the major product
is now the monosulfonate salt.28 The bis-nitrile is also present
along with very minor amounts of unidentified species.28 The
middle section of Scheme 7 shows the relevant CD3CN 1H and
13C NMR data, and the bottom section of the scheme gives the
analogous CD2Cl2 results. NOESY data in CD2Cl2 solution show
selective contacts from the p-CH3C6H4SO3- ligand to both the
Cp* and the allyl group, thereby confirming that this ligand is
complexed (see Figure 1). The lower right section of the scheme
ammonium methane sulfonate salt in CD3CN (19.33 × 10-10
,
m2 s-1), prepared for comparison purposes (see Experimental
Part). This intermediate D-value is consistent with rapid
exchange of the methyl sulfonate ligand on the NMR time
scale. 1H NMR measurements on a mixture of 1 and
CH2dCHCH2OH in CD3CN, without acid, show this complex
does not react with the alcohol. We conclude that, as
expected, the presence of strong acid facilitates the oxidative
addition step by converting the (presumably complexed) allyl
alcohol into a substrate with water as the leaving group.
-
gives NMR data for the CH3SO3 analogue.
These reactions support (1) the idea that monosulfonate
complexes are relatively stable, (2) that the oxidative addition
step is facile, and (3) reasonably enough, that the sulfonate anion
cannot compete favorably for the ruthenium center in the
presence of a large excess of acetonitrile.
Solid-State Structures. The structure of the dicationic bis
aquo-complex [Ru(Cp*)(η3-C3H5)(H2O)2]2+, 12, was determined
by X-ray diffraction methods, and a view of the cation is given
in Figure 2, along with a selection of bond lengths and bond
angles. Although Ru(H2O) complexes are known,29-33 this is
the first such structure with camphor sulfonic acid anions and
supports the view that this bulky sulfonic acid anion will not
be a strong ligand. The immediate coordination sphere contains
the Cp*, the η3-C3H5, and two water molecules. The η3-allyl
ligand has the central carbon C-H vector pointing away from
the Cp*, and all of the Ru-O and Ru-C(allyl)34,35 separations
are consistent with the literature. We note that the Ru-Cp*
bonding is slightly asymmetric in that there are three distances
at ca. 2.18 Å and two at ca. 2.28 Å.
To obtain data with respect to the observed difference in the
b/l ratio when the alcohol substrate has a bulky ortho substituent,
we have allowed 1 equiv of either PhCH(OH)CHdCH2 or
2-CH3C6H4CH(OH)CHdCH2 to react with a mixture of 1 equiv
each of 1 and p-CH3C6H4SO3H at ambient temperature in
CD3CN solution. 1H and 13C NMR data for the bis-nitrile
products that form, [Ru(Cp*)(η3-PhCHCHCH2)(CH3CN)2]2+ and
[Ru(Cp*)(η3-2-CH3C6H4CHCHCH2)(CH3CN)2]2+, are given in
Scheme 6. We note that the two substituted terminal allyl carbon
resonances appear at δ ) 102.9 and 107.1, for the Ph and 2-tolyl
analogues, respectively. This difference may have some sig-
nificance since a higher frequency 13C allyl resonance is often
associated with a weaker bond.12
The O(1)-Ru-O(2) angle associated with the water mol-
ecules is ca. 79°, whereas the various O-S-O angles from the
two anions fall in the range ca. 110-115°. The six S-O
separations do not differ much and fall in the narrow range ca.
1.42-1.47 Å. The positions of the two anions are consistent
with H-bonding interactions between the coordinated water and
the oxygen atoms of the sulfonic acid anions.
In a separate preparative experiment (see Experimental Part),
the acetonitrile solvent from the reaction with 2-CH3C6H4CH-
(25) Kumar, P. G. A. Aust. J. Chem. 2006, 59, 78–78.
(26) Antalek, B. Concepts Magn. Reson. Part A 2007, 30A, 219–235.
(27) Not all of the crude isolated orange material is soluble in
dichloromethane solution, so that the relative amount of [Ru(Cp*)(η3-2-
CH3C6H4CHCHCH2)(CH3CN)(p-CH3C6H4SO3)]+ is uncertain. For example,
in CD2Cl2 solution we estimate that 60-65% of the material is Ru(Cp*)(η3-
2-CH3C6H4CHCHCH2)(CH3CN)(p-CH3C6H4SO3)+.
The neutral Ru(Cp*)(η3-C3H5)(SO4) complex, 13, mentioned
above, was prepared as shown in eq 6, and a view of the
structure is given in Figure 3, together with a selection of bond

Ru-Sulfonate-Catalyzed Allylation of Indoles
Organometallics, Vol. 28, No. 12, 2009 3443
Scheme 4. Synthesis of Ruthenium Species Containing the Sulfonate Anion
lengths and bond angles. There are not many structures36-39 of
sulfate ligands in connection with Ru chemistry (see for example
16-18). The study by Volland et al.,37 which includes structure
17, also includes Ru complexes whose structures possess
coordinated CF3SO3-, CF3CO2-, and H2O.
tions in 12. The three Ru-C(allyl) distances are normal and
very close to those found for 12.
The four sulfate S-O bond lengths, S(1)-O(1) 1.518(3),
S(1)-O(2) 1.527(3), S(1)-O(3) 1.429(3), and S(1)-O(4)
1.437(3), suggest localized bonding in that the two S-O bonds
associated with the metal, at ca. 1.52 Å, are significantly longer
than the remaining two S-O distances at ca. 1.43 Å. The
O(1)-Ru(1)-O(2) angle at 66.86(10)° is small (as is the
analogous bond angle in 16, ca. 69°).
DFT Studies. The various catalytic and NMR experiments
described above suggest the involvement of one complexed
sulfonate anion. However, since the metal is a stereogenic center,
a cation with the empirical formula [Ru(Cp*)(η3-PhCH-
CHCH2)(CH3CN)(RSO3)]+ can exist as a number of different
diastereomers. To shed further light on this chemistry, we have
carried out DFT calculations40 on the two isomers of [Ru(Cp*)(η3-
PhCHCHCH2)(CH3CN)(p-CH3C6H4SO3)]+, 19a,b, and the
four isomeric forms of [Ru(Cp*)(η3-(2-CH3C6H4)CHCHCH2)-
(CH3CN)(p-CH3C6H4SO3)]+, 20a-d.
The immediate coordination sphere contains the Cp*, the η3-
C3H5, and the chelated sulfate anion. Again, the allyl ligand
has the central carbon C-H vector pointing away from the Cp*,
and the Ru-Cp* bonding is slightly asymmetric. The two
Ru-O bond lengths, Ru(1)-O(1), 2.108(3) Å and Ru(1)-O(2),
2.103(3) Å, are marginally longer than those for 16, Ru-O
2.079(7) Å, but not quite as long as the Ru-O(water) separa-
(33) Mahon, M. F.; Whittlesey, M. K.; Wood, P. T. Organometallics
1999, 18, 4068–4074.
(28) In both solvents for both reactions it is clear that small quantities
(about 5% or less) of several other η3-allyl species are present. An earlier
report14c on [Ru(Cp*)(η3-C3H5)(CH3CN)2](PF6)2 gave NMR data in acetone
solution. The data for a pure sample in CD3CN are as follows: 1H NMR
(CD3CN, 500 MHz) δ 5.70 (m, 1H, C-Hcentral), 4.55 (d, 2H, J ) 6.0 Hz,
C-Hsyn), 3.04 (d, 2H, J ) 10.5 Hz, C-Hanti), 2.53 (s, 6H,CH3CN), 1.81 (s,
15H, C5Me5). 13C NMR (125 MHz, CD3CN): δ 133.6 (CH3CN), 110.4
(C5Me5), 99.9 (Ccentral), 72.2 (Cterminal), 9.5 (C5Me5), 4.7 (CH3CN).
(29) Asano, H.; Katayama, K.; Kurosawa, H. Inorg. Chem. 1996, 35,
5760–5761.
(30) Davies, D. L.; Fawcett, J.; Garratt, S. A.; Russell, D. R. Organo-
metallics 2001, 20, 3029–3034.
(31) Kurosawa, H.; Asano, H.; Miyaki, Y. Inorg. Chem. Acta 1998, 270,
87–94.
(34) Kondo, T.; Ono, H.; Satake, N.; Mitsudo, T.; Watanabe, Y.
Organometallics 1995, 14, 1945–1953.
(35) Mbaye, M. D.; Demerseman, B.; Renaud, J. L.; Toupet, L.; Bruneau,
C. AdV. Synth. Catal. 2004, 346, 835–841.
(36) (a) Reed, J.; Soled, S. L.; Eisenberg, R. Inorg. Chem. 1974, 13,
3001–3005. (b) He, X.-D.; Chaudret, B.; Lahoz, F.; Lopez, J. A. J. Chem.
Soc., Chem. Commun. 1990, 958–959. (c) Flu¨gel, R.; Windmu¨ller, B.;
Gevert, O.; Werner, H. Chem. Ber. 1996, 129, 1007–1013.
(37) Volland, M.; Hansen, S. M.; Rominger, F.; Hofmann, P. Organo-
metallics 2004, 23, 800–816.
(38) Nakatani, E.; Takai, Y.; Kurosawa, H. J. Organomet. Chem. 2007,
692, 278–285.
(39) Toledo, J. C.; Neto, B. S. L.; Franco, D. W. Coord. Chem. ReV.
2005, 249, 419–431.
(32) Dadci, L.; Elias, H.; Frey, U.; Hornig, A.; Koelle, U.; Merbach,
A. E.; Paulus, H.; Schneider, J. S. Inorg. Chem. 1995, 34, 306–315.
(40) Parr, R. G.; Yang, W. Density Functional Theory of Atoms and
Molecules; Oxford University Press: New York, 1989.

3444 Organometallics, Vol. 28, No. 12, 2009
Gruber et al.
Table 6. Allylation of Indole by PhCH(OH)CHdCH2 and Its
o-Methyl-Substituted Analogue Using Preformed Ru(IV) Catalystsa
1
Figure 1. Sections of the 700 MHz H 2D NOESY for the cation
Ru(Cp*)(η3-C3H5)(CH3CN)(p-CH3C6H4SO3)+ in CD2Cl2 solution
showing selective contacts from the coordinated sulfonate to the
Cp*methyl groups (upper section) and to the syn allyl proton closest
to the complexed sulfonate (lower section).
Note that in 20 we show isomers that differ only in that the
2-CH3 substituent of the tolyl group is either close to C2 or
remote from this atom and directed toward the Cp* ligand (see
20a and 20b). Although one might have expected that the
relative position of the sulfonate with respect to the allyl aryl
group would markedly affect the energy, this is not the case.
The sterically less favored structures having the arylsulfonate
ligand pseudo-cis to the aryl group of the allyl ligand are only
slightly less stable.
Scheme 9 presents a summary of the Ru-C(allyl) bond
distances (Å) for 19 and 20. As expected, on the basis of
previous studies,9,12,13 the Ru-C3 allyl separation is not very
sensitive to the various changes in structure and remains at about
2.15-2.16 Å. However, the Ru-C1 separation is both longer
than the Ru-C3 distance and sensitive to whether the allyl has
a phenyl or a 2-tolyl group. For example, considering the most
stable diastereomer of each complex 19b and 20a (see the
bottom of Scheme 9), one finds a 0.1 Å difference in the Ru-C1
bond length, while the Ru-C3 distances are within 0.01 Å in
the two molecules. These geometric differences are corroborated
by the Wiberg indices (WI)41 of the corresponding bonds (see
Supporting Information, tables), confirming an electronic reason
for the changes observed. The Wiberg index associated with
the Ru-C1 bond drops from WI ) 0.34 in 19b to WI ) 0.30
in 20a, whereas for the Ru-C3 bonds the WI values are within
0.01 for both species. These results suggest a larger distortion
for the allyl ligand with the 2-tolyl group in 20a than for the
allyl with the phenyl group in 19b due to a weaker Ru-C1
bond in the former complex.
a Reaction conditions: CD3CN (0.5 mL), indole (0.07 mM), allyl
alcohol (0.07 mM), complex (0.0035 mM
temperature. For 100% conversion.
) 5 mol %), room
b
Scheme 5. Plausible Mechanism for the Appearance of the
-
Branched Product in the Allylation Reaction (PF6 not
shown)
(41) (a) Wiberg, K. B. Tetrahedron 1968, 24, 1083. (b) Wiberg indices
are electronic parameters related to the electron density between atoms.
They can be obtained from a natural population analysis and provide an
indication of the bond strength.
In Scheme 8 we show the optimized geometries for these
six species along with the relative energies between the isomers.

Ru-Sulfonate-Catalyzed Allylation of Indoles
Organometallics, Vol. 28, No. 12, 2009 3445
Scheme 6. Oxidative Additions of Aryl Allyl Alcohols and NMR Showing the Difference between o-Tolyl and Phenyl Analogues
The charges calculated via a natural population analysis
(NPA)42 reflect the differences in the Ru-allyl bond strength
discussed above (see Supporting Information). Stronger Ru-allyl
bonds are associated with enhanced back-donation from Ru to
allyl12,14a and correspond to electron richer ligands. This is
reflected in the total charges associated with the allyl ligand,
+0.35 in 19b and +0.38 in 20a, indicating a less positive ligand
and, thus, a stronger Ru-allyl interaction in 19b. This structural
dissimilarity is accompanied by differences in the atomic charges
calculated for the allyl carbon C1: -0.17 for the phenyl
analogue, 19b, and -0.15 for the 2-tolyl derivative, 20a. The
charges at the CH2 terminus, C3, are quite similar for both
complexes (-0.42 in 19b and -0.43 in 20a) and much more
negative than the values calculated for C1. Consequently, in
the 2-tolyl set the Ru-C1 bond is weaker and the C-atom is
more positive (less negative) and, therefore, more likely to attract
the incoming nucleophile and yield the branched product.
Summarizing, the calculations for the presumed to be important
sulfonate salts [Ru(Cp*)(η3-C3H5)(CH3CN)(RSO3)]+ suggest
that the changes in the observed b/l ratios are likely to arise
from structural distortions due to the presence of the 2-sub-
stituent.
Conclusions
The combination of [Ru(Cp*)(CH3CN)3](PF6) and one of the
sulfonic acids 3-5 catalyzes the allylation of a variety of indole
compounds using alcohols of the form ArCH(OH)CHdCH2 in
<30 min at ambient temperature. It is not necessary to waste a
leaving group, and no additives (such as base) are necessary.
The branched products are favored, and in a number of
examples, branched-to-linear ratios in excess of 20 are observed.
The catalyst is selective in that there is no N-allylation or diallyl
ether formation. H2SO4, CF3SO3H, HBF4, and carboxylic acids
are either poorer or ineffective cocatalysts. The preformed
isolated complexes [Ru(Cp*)(η3-C3H5)(RSO3)2] are efficient
catalyst precursors; however, the data suggest that one of the
active species is the monosulfonate cationic complex [Ru(Cp*)(η3-
C3H5)(CH3CN)(RSO3)]+. Stoichiometric oxidative addition reac-
tions (including those starting from CH3S(O)2OCH2CHdCH2
or (p-CH3C6H4)S(O)2OCH2CHdCH2) are shown to be relatively
rapid. The NMR studies reveal that the monosulfonate com-
plexes are formed. These salts are not very stable in acetonitrile
solution; however they are readily characterized in dichlo-
romethane. The DFT calculations have provided a rationale for
the relatively large observed b/l ratios based on structural
(42) (a) Carpenter, J. E.; Weinhold, F. J. Mol. Struct. (THEOCHEM)
1988, 169, 41. (b) Carpenter, J. E. Ph.D. thesis, University of Wisconsin,
Madison WI, 1987. (c) Foster, J. P.; Weinhold, F. J. Am. Chem. Soc. 1980,
102, 7211. (d) Reed, A. E.; Weinhold, F. J. Chem. Phys. 1983, 78, 4066.
(e) Reed, A. E.; Weinhold, F. J. Chem. Phys. 1983, 78, 1736. (f) Reed,
A. E.; Weinstock, R. B.; Weinhold, F. J. Chem. Phys. 1985, 83, 735. (g)
Reed, A. E.; Curtiss, L. A.; Weinhold, F. Chem. ReV. 1988, 88, 899. (h)
Weinhold, F.; Carpenter, J. E. The Structure of Small Molecules and Ions;
Plenum: NY, 1988; p 227.

3446 Organometallics, Vol. 28, No. 12, 2009
Gruber et al.
Scheme 7. NMR Support for the Proposed Sulfonate Salts
S2 (12) and S3 (13), respectively. Details of the remaining bond
lengths and bond angles have been depositied. All atoms except
hydrogen atoms and atoms of disordered molecules were refined
with anisotropic displacement parameters. In general, H-atoms were
placed at calculated positions based on stereochemical consider-
ations and refined according to the riding model. In 12, the H-atoms
of the water molecules were located in the difference Fourier map
and refined at a constrained O-H distance. The allyl molecule in
13 is disordered over two sites and was described by split positions.
Synthesis of Allyl Alcohols and Allyl Sufonates. The allyl
alcohols used in the allylation reaction were synthesized according
to a modified literature procedure.45a The modification consisted
of performing the addition of vinylmagnesium bromide (1 M in
THF, 1.2 equiv) at -78 °C within 15 min with subsequent stirring
at rt for 15 min. The alcohols were isolated by distillation under
vacuum. The allyl sulfonates were prepared according to the
literature.45b
distortions due to the presence of the bulky 2-substituent in the
alcohol substrate.
Experimental Part
General Information. All air-sensitive manipulations were
carried out under a nitrogen atmosphere. All solvents were dried
over an appropriate drying agent and then distilled under nitrogen.
Acetone-d6 and CD2Cl2 were distilled over CaSO4 and CaH2,
respectively, and stored under nitrogen. CD3CN was dried over
molecular sieves and stored under nitrogen. All commercially
available starting materials were purchased from commercial
1
sources and used as received. H, 13C, and 2D NMR spectra were
recorded with Bruker DPX-250, 300, 400, 500, and 700 MHz
spectrometers at room temperature. Chemical shifts are given in
ppm and referenced relative to TMS. The 1H NOESY experiments
were acquired using a standard three-pulse sequence and a mixing
time of 600 ms. Diffusion measurements were made on 2 mmol/L
solutions. Elemental analyses were performed at ETHZ.
X-ray Structure Analyses. Data sets were obtained using a
Bruker SMART Platform diffractometer equipped with a CCD
detector (graphite-monochromated Mo KR radiation, λ ) 0.71073
Å) at 230 K (12) and 233 K (13), respectively. The structures were
solved by direct methods.43 The crystallographic data and R-values
of the full-matrix least-squares refinements44 are given in Tables
Triethylammonium Methanesulfonate and Triethylammonium
p-Toluenesulfonate. These salts, which were used as references in
1
the H NMR PGSE studies, were prepared by addition of triethyl
amine to an etheral solution of either methanesulfonic acid or
p-toluenesulfonic acid and subsequent evaporation of the ether under
vacuum.
NMR-Monitored Allylation of Indoles. In a typical example,
indole (0.07 mmol) was added to a CD3CN (0.5 mL) solution of

Ru-Sulfonate-Catalyzed Allylation of Indoles
Organometallics, Vol. 28, No. 12, 2009 3447
Scheme 8. Structures and Energies (kcal/mol) for
[Ru(Cp*)(C6H5CHCHCH2)(CH3CN)(CH3C6H4SO3)]+, 19a,b,
and [Ru(Cp*)(η3-(o-CH3C6H4)CHCHCH2)(CH3CN)(CH3C6H4-
SO3)]+, 20a-d, Containing Complexed p-CH3C6H4SO3
Ligands
Figure 2. Selected bond lengths (Å) and bond angles (deg) for 12:
Ru(1)-O(1) 2.119(3), Ru(1)-O(2) 2.141(3), Ru(1)-C(1) 2.199(5),
Ru(1)-C(2) 2.114(4), Ru(1)-C(3) 2.183(4), Ru(1)-C(10) 2.179(5),
Ru(1)-C(20) 2.189(5), Ru(1)-C(30) 2.283(3), Ru(1)-C(40)
2.279(5), Ru(1)-C(50) 2.173(5), S(1)-O(5) 1.446(4), S(1)-O(4)
1.452(3), S(1)-O(3) 1.461(4), S(1)-C(60A) 1.80(2), S(2)-O(9)
1.419(5), S(2)-O(8) 1.457(4), S(2)-O(7) 1.471(5), S(2)-C(70)
1.795(7), O(1)-Ru(1)-O(2), 79.02(13), O(5)-S(1)-O(4) 112.9(2),
O(5)-S(1)-O(3) 112.6(2), O(4)-S(1)-O(3) 112.4(2), O(5)-S(1)-
C(60A) 109.0(7), O(4)-S(1)-C(60A) 107.0(7), O(3)-S(1)-C(60A)
102.2(4), O(9)-S(2)-O(8) 114.8(3), O(9)-S(2)-O(7) 112.9(3),
O(8)-S(2)-O(7) 110.6(2), O(9)-S(2)-C(70) 108.6(3), O(8)-
S(2)-C(70) 107.0(3), O(7)-S(2)-C(70) 101.8(3). Only one ori-
entation of the disordered camphor-sulfonate counterion is shown.
Scheme 9. Calculated Bond Lengths (Å) for the Allyl
Carbons
Figure 3. Selected bond lengths (Å) and bond angles (deg) for 13:
Ru(1)-O(2) 2.103(3), Ru(1)-O(1) 2.108(3), Ru(1)-C(3A) 2.279(7);
Ru(1)-C(2A), 2.163(6), Ru(1)-C(1A) 2.181(8), Ru(1)-C(50)
2.188(3), Ru(1)-C(40) 2.173(3), Ru(1)-C(30) 2.211(3), Ru(1)-
C(20) 2.276(4), Ru(1)-C(10) 2.251(3), Ru(1)-S(1) 2.739 (9),
S(1)-O(1) 1.518(3), S(1)-O(2) 1.527(3), S(1)-O(3) 1.429(3),
S(1)-O(4) 1.437(3), O(2)-Ru(1)-O(1) 66.86(10), O(3)-S(1)-O(4)
113.54(19), O(3)-S(1)-O(1) 111.3(2), O(4)-S(1)-O(1) 110.9(2),
O(3)-S(1)-O(2) 110.7(2), O(4)-S(1)-O(2) 110.3(2), O(1)-S(1)-
O(2) 99.26(14). Only one orientation of the disordered allyl
molecule (C1A, C2A, C3A) is shown.
[Ru(Cp*)(η3-C3H5)(p-CH3C6H4SO3)2], 10. Toluene (16 mL)
was added to an acetonitrile (16 mL) solution of [Ru(Cp*)(η3-
C3H5)Cl2]46 (0.084 g, 0.24 mmol) and p-CH3C6H4SO3Ag (0.134
g, 0.48 mmol). The reaction mixture was stirred at room temperature
for 17 h, after which time the solution was evaporated under
vacuum. The resulting residue was dissolved in dichloromethane
(3 mL) and filtered. After evaporation of the solvent, the resulting
solid was washed with cold (0 °C) THF (3 × 1 mL) and dried
1
the allylic alcohol (0.07 mmol), [Ru(Cp*)(MeCN)3]PF6 (0.0023 g,
0.035 mmol), and the sulfonic acid (0.0035 mM), in an oven-dried
NMR tube. The progress of the reaction was then monitored by 1H
NMR at ambient temperature.
under vacuum to afford an orange solid (0.103 g, 69%). H NMR
(400 MHz, CD2Cl2): δ 7.56 (4H, d, J ) 8.0 Hz), 7.13 (4H, d, J )
8.0 Hz), 6.26-6.18 (1H, m), 5.30 (2H, d, J ) 6.0 Hz), 2.83 (2H,
d, J ) 10.4 Hz), 2.39 (6H, s), 1.66 (15H, s). 13C NMR (100 MHz,

3448 Organometallics, Vol. 28, No. 12, 2009
Gruber et al.
CD2Cl2): δ 142.5, 140.9, 128.9, 125.9, 108.8, 100.1, 66.7, 21.1,
9.8. Anal. Calcd for C27H34O6RuS2: C, 52.33; H, 5.53. Found: C,
52.05; H, 5.52. Crystals were obtained by layering an acetone
solution with ether.
Chemistry of the Allyl Sulfonate Ethers with 1. Allyl tosylate
(12.6 mg, 0.059 mmol) was added to either a CD3CN or a CD2Cl2
(0.5 mL) solution of [Ru(Cp*)(CH3CN)3]PF6 (30 mg, 0.059 mmol)
in an NMR tube, and the spectra were recorded. Allyl mesylate
(8.1 mg, 0.059 mmol) was added to either a CD3CN or a CD2Cl2
(0.5 mL) solution of [Ru(Cp*)(CH3CN)3]PF6 (30 mg, 0.059 mmol)
in an NMR tube, and the spectra were recorded.
Computational Details. The calculations were performed using
the GAUSSIAN 03 software package47 and the PBE1PBE func-
tional, without symmetry constraints. That functional uses a hybrid
generalized gradient approximation (GGA), including a 25%
mixture of Hartree-Fock48 exchange with DFT40 exchange-
correlation, given by a Perdew, Burke, and Ernzerhof functional
(PBE).49 The optimized geometries were obtained with the LanL2DZ
basis set50 augmented with a f-polarization function51 for Ru and
a standard 6-31G(d,p)52 for the remaining elements. Frequency
calculations were performed, yielding no imaginary frequency
modes and confirming the nature of the stationary points as minima.
A natural population analysis (NPA)42 and the resulting Wiberg
indices41 were used to study the electronic structure and bonding
of the optimized species.
[Ru(Cp*)(η3-C3H5)(CH3SO3)2], 11. Toluene (19 mL) was added
to an acetonitrile (19 mL) solution of [Ru(η3-C3H5)(Cp*)Cl2] (0.100
g, 0.29 mmol) and CH3SO3Ag (0.117 g, 0.58 mmol). The reaction
mixture was stirred at room temperature for 14 h, after which time
the solution was evaporated under vacuum. The resulting residue
was dissolved in dichloromethane (3 mL) and filtered. After
evaporation of the solvent the resulting solid was washed with cold
(0 °C) THF (2 × 1 mL) and dried under vacuum to afford an orange
1
solid (0.093 g, 69%). H NMR (300 MHz, CD2Cl2): δ 6.48-6.37
(1H, m), 5.05 (2H, d, J ) 6.3 Hz), 2.86 (2H, d, J ) 10.2 Hz), 2.73
(6H, s), 1.64 (15H, s). 13C NMR (75 MHz, CD2Cl2): δ 108.6, 100.0,
67.7, 41.6, 9.5. Anal. Calcd for C15H26O6RuS2: C, 38.53; H, 5.60.
Found: C, 39.33; H, 5.63.
[Ru(Cp*)(SO4)(η3-C3H5)], 13. Ag2SO4 (0.488 g, 1.29 mmol)
was added to an acetonitrile (30 mL) solution of [Ru(Cp*)(η3-
C3H5)Cl2] (0.15 g, 0.43 mmol). The reaction mixture was stirred
at room temperature for 18 h, after which time the solution was
evaporated under vacuum. The resulting residue was dissolved
in CH2Cl2 and filtered through Celite. The filtrate was evaporated,
and the residue was dried under vacuum. This sequence was
repeated twice to yield a light brown solid (0.143 g, 89%). A
dichloromethane solution of this solid was then layered with
diethyl ether and stored at -6 °C, to afford crystals of 13 suitable
for X-ray diffraction. 1H NMR (CD2Cl2, 500 MHz): δ 5.25-5.21
(m, 1H, C-Hcentral), 4.03 (d, 2H, J ) 6.5 Hz, C-Hsyn), 2.63 (d,
2H, J ) 10.5 Hz, C-Hanti), 1.65 (s, 15H, C5Me5). 13C NMR
(CD2Cl2, 125 MHz): δ 107.3 (C5Me5), 101.5 (Ccentral), 65.6
(Cterminal), 9.3 (C5Me5). 1H NMR (CD3CN, 300 MHz) δ 5.22-5.13
(m, 1H, C-Hcentral), 4.00 (d, 2H, J ) 6.3 Hz, C-Hsyn), 2.79 (d,
2H, J ) 10.5 Hz, C-Hanti), 1.67 (s, 15H, C5Me5). 13C NMR (75
MHz, CD3CN): δ 107.4 (C5Me5), 101.0 (Ccentral), 65.2 (Cterminal),
8.5 (C5Me5).
Acknowledgment. P.S.P. thanks the Swiss National Sci-
ence Foundation, the ETH Zurich, COST Action D24
“Sustainable Chemical Processes: Stereoselective Transition
Metal-Catalysed Reactions”, and COST D40-“Innovative
Catalysis: New Processes and Selectivities” for support, as
well as the Johnson Matthey company for the loan of
ruthenium salts.
Supporting Information Available: Supplementary structural
and electronic data, as well as tables with atomic coordinates for
all the optimized species. Table of catalytic data from ref 14a,14a
and cif files for the structural data on 12 and 13. This material is
available free of charge via the Internet at http://pubs.acs.org.
OM900168Y
Anal. (%) Calcd for C13H20O4SRu: C 41.81, H 5.40. Found: C
41.33, H 5.36. HR MALDI-MS: calcd for [MH+] 375.0198, found
375.0198.
(47) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb,
M. A.; Cheeseman, J. R.; Montgomery, J. A., Jr.; Vreven, T.; Kudin, K.
N.; Burant, J. C.; Millam, J. M.; Iyengar, S. S.; Tomasi, J.; Barone, V.;
Mennucci, B.; Cossi, M.; Scalmani, G.; Rega, N.; Petersson, G. A.;
Nakatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.;
Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Klene, M.; Li,
X.; Knox, J. E.; Hratchian, H. P.; Cross, J. B.; Adamo, C.; Jaramillo, J.;
Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.;
Pomelli, C.; Ochterski, J. W.; Ayala, P. Y.; Morokuma, K.; Voth, G. A.;
Salvador, P.; Dannenberg, J. J.; Zakrzewski, V. G.; Dapprich, S.; Daniels,
A. D.; Strain, M. C.; Farkas, O.; Malick, D. K.; Rabuck, A. D.;
Raghavachari, K.; Foresman, J. B.; Ortiz, J. V.; Cui, Q.; Baboul, A. G.;
Clifford, S.; Cioslowski, J.; Stefanov, B. B.; Liu, G.; Liashenko, A.; Piskorz,
P.; Komaromi, I.; Martin, R. L.; Fox, D. J.; Keith, T.; Al-Laham, M. A.;
Peng, C. Y.; Nanayakkara, A.; Challacombe, M.; Gill, P. M. W.; Johnson,
B.; Chen, W.; Wong, M. W.; Gonzalez, C.; Pople, J. A. Gaussian 03,
Revision C.02; Gaussian, Inc.: Wallingford, CT, 2004.
(48) Hehre, W. J.; Radom, L.; Schleyer, P. v. R.; Pople, J. A. Ab Initio
Molecular Orbital Theory; John Wiley & Sons: New York, 1986.
(49) (a) Perdew, J. P.; Burke, K.; Ernzerhof, M. Phys. ReV. Lett. 1997,
78, 1396. (b) Perdew, J. P. Phys. ReV. B 1986, 33, 8822.
(50) (a) Dunning, T. H., Jr.; Hay, P. J. Modern Theoretical Chemistry;
Schaefer, H. F., III, Ed.; Plenum: New York, 1976; Vol. 3, p 1. (b) Hay,
P. J.; Wadt, W. R. J. Chem. Phys. 1985, 82, 270. (c) Wadt, W. R.; Hay,
P. J. J. Chem. Phys. 1985, 82, 284. (d) Hay, P. J.; Wadt, W. R. J. Chem.
Phys. 1985, 82, 2299.
Attempt to Synthesize [Ru(Cp*)(η3-2-CH3C6H4CHCHCH2)-
(CH3CN)(p-CH3C6H4SO3)]2+. 1-(2-Tolyl)prop-2-en-1-ol (17.6 mg,
0.119 mmol) was added to an acetonitrile (2.5 mL) solution of
[Ru(Cp*)(CH3CN)3]PF6 (60 mg, 0.119 mmol) and p-toluenesulfonic
acid monohydrate (22.6 mg, 0.119 mmol). The resulting orange
solution was stirred at room temperature for 30 min, after which
time the solution was concentrated under vacuum. The resulting
crude material was washed two times with ether and then dried to
afford 87 mg of an orange solid. This solid is not completely soluble
in CD2Cl2.
Oxidative Addition Reactions of ArCH(OH)CHdCH2 (Ar
) Ph or 2-CH3C6H4). 1-(2-Tolyl)prop-2-en-1-ol (8.8 mg, 0.059
mmol) was added to an acetonitrile-d3 (0.5 mL) solution of
[Ru(Cp*)(CH3CN)3]PF6 (30 mg, 0.059 mmol) and p-toluenesulfonic
acid monohydrate (11.3 mg, 0.059 mmol) in an NMR tube.
R-Vinylbenzyl alcohol (8.08 mg, 0.059 mmol) was added to an
acetonitrile-d3 (0.5 mL) solution of [Ru(Cp*)(CH3CN)3]PF6 (30 mg,
0.059 mmol) and p-toluenesulfonic acid monohydrate (11.3 mg,
0.059 mmol) in an NMR tube.
(43) Sheldrick, G. M. SHELXLS-97; University of Go¨ttingen: Germany,
1997.
(44) Sheldrick, G. M. SHELXL-97; University of Go¨ttingen: Germany,
1997.
(51) Ehlers, A. W.; Bo¨hme, M.; Dapprich, S.; Gobbi, A.; Ho¨llwarth,
A.; Jonas, V.; Ko¨hler, K. F.; Stegmann, R.; Veldkamp, A.; Frenking, G.
Chem. Phys. Lett. 1993, 208, 111.
(45) (a) Briot, A.; Baehr, C.; Brouillard, R.; Wagner, A.; Mioskowski,
C. J. Org. Chem. 2004, 69, 1374–1377. (b) Emmons, W. D.; Ferris, H. F.
J. Am. Chem. Soc. 1953, 9, 2257–2257.
(46) Nagashima, H.; Mukai, K.; Shiota, Y.; Ara, K.; Itoh, K.; Suzuki,
H.; Oshima, N.; Morooka, Y. Organometallics 1985, 4, 1314–1315.
(52) (a) Ditchfield, R.; Hehre, W. J.; Pople, J. A. J. Chem. Phys. 1971,
54, 724. (b) Hehre, W. J.; Ditchfield, R.; Pople, J. A. J. Chem. Phys. 1972,
56, 2257. (c) Hariharan, P. C.; Pople, J. A. Mol. Phys. 1974, 27, 209. (d)
Gordon, M. S. Chem. Phys. Lett. 1980, 76, 163. (e) Hariharan, P. C.; Pople,
J. A. Theor. Chim. Acta 1973, 28, 213.