An alternate route to the active chiral hydrogenation catalysts [Ru(bisphosphine)(H)(solvent)3]+: Synthesis, characterization, and catalytic evaluation

Article abstract of DOI:10.1021/om049740x

We report an improved synthesis of cis-[Ru(CH₃CN) ₂((1-3-n)-C₃H₅)((1,2:5,6-n)-C₈H ₁₂)]BF₄ and its use in the synthesis of [Ru(bisphosphine)((1-3:5,6-n)-C₈H₁₁

Full text of DOI:10.1021/om049740x

4564
Organometallics 2004, 23, 4564-4568
An Alter n a te Rou te to th e Active Ch ir a l Hyd r ogen a tion
Ca ta lysts [Ru (bisp h osp h in e)(H)(solven t)3]+: Syn th esis,
Ch a r a cter iza tion , a n d Ca ta lytic Eva lu a tion
J ason A. Wiles,† Christopher J . A. Daley,‡ Robin J . Hamilton,
Carolyn G. Leong, and Steven H. Bergens*
Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
Received April 9, 2004
We report an improved synthesis of cis-[Ru(CH3CN)2((1-3-η)-C3H5)((1,2:5,6-η)-C8H12)]BF4
and its use in the synthesis of [Ru(bisphosphine)((1-3:5,6-η)-C8H11)(CH3CN)]BF4 (where
bisphosphine ) (R)-BINAP, (R)-Tol-BINAP). Thermolyses of the complexes [Ru(bisphos-
phine)((1-3:5,6-η)-C8H11)(CH3CN)]BF4 afford [Ru(bisphosphine)((1-5-η)-C8H11)]BF4, which
serve as convenient precatalysts to the active hydrogenation catalysts fac-[Ru(bisphosphine)-
(H)(sol)3]BF4 (sol ) THF, acetone, i-PrOH). We compare the properties and activities of these
catalysts with those of related, established systems.
In tr od u ction
As part of our ongoing efforts to prepare highly
reactive ruthenium catalysts, we now describe in this
report an alternate, convenient synthesis of the ruthe-
nium precursor cis-[Ru(CH3CN)2((1-3-η)-C3H5)((1,2:5,6-
η)-C8H12)]BF4 (1), its use in the synthesis of [Ru((R)-
BINAP)((1-5-η)-C8H11)]BF4 (2) and the (R)-Tol-BINAP
analogue (3), and the reactions of 2 and 3 with hydrogen
to form the active catalysts fac-[Ru(bisphosphine)(H)-
(sol)3]BF4 (4, bisphosphine ) (R)-BINAP; 5, bisphos-
phine ) (R)-Tol-BINAP; sol ) THF, acetone, i-PrOH).
The TOF and enantioselectivity of 4 as catalyst for the
hydrogenation of (Z)-methyl R-acetamidocinnamate
(MAC) are compared with those of [Ru((R)-BINAP)(H)-
(CH3CN)n(sol)3-n]BF4 (6; sol ) acetone, methanol, n )
0-3)sthe system reported previously by us4 and
Salzer5sand with those of the classic rhodium catalyst
system [Rh((R)-BINAP)(sol)2]BF4 (7).
Enantioselective hydrogenation using catalysts con-
taining ruthenium(II) and 2,2′-bis(diphenylphosphino)-
1,1′-binaphthalene (BINAP), or related bisphosphines,
is an important technology used widely in industrial and
academic syntheses.1 The scope of this process is broad,
with catalysts usually exhibiting extraordinarily high
turnover frequencies (TOF’s), turnover numbers (TON’s),
and enantiomeric excesses (ee’s). The ruthenium cata-
lysts commonly employed in industrial-scale reactions,
however, do not effect hydrogenations of tetrasubsti-
tuted olefin precursors at practical rates. For example,
workers at Firmenich and the Geneˆt laboratories and
this group only recently described catalyst mixtures
suitable for production of (+)-cis-methyl dihydrojas-
monate, a perfumery chemical, via hydrogenation of a
tetrasubstituted olefin.2 We and workers at Firmenich3
also recently described a general synthesis of the active
catalysts in these mixtures. These catalysts, of the form
fac-[Ru(bisphosphine)(H)(sol)3]BF4 (sol ) weakly co-
ordinating solvento ligands, e.g., THF and acetone),
were prepared from the zerovalent complex Ru((1,2:5,6-
η)-C8H12)((1-6-η)-C8H10)sa versatile but challenging
precursor.
Resu lts a n d Discu ssion
Syn th eses a n d Ch a r a cter iza tion of Ca ta lyst P r e-
cu r sor s. Schrock et al.6 reported that the reaction of
Ru((1-3-η)-C3H5)2((1,2:5,6-η)-C8H12) with [Ph3C]BF4 in
mixtures of acetonitrile and methylene chloride gave cis-
[Ru(CH3CN)2((1-3-η)-C3H5)((1,2:5,6-η)-C8H12)]BF4 (1)
and Ph3CCH2CHdCH2. We now report that 1 is more
conveniently prepared using HBF4‚Et2O rather than
[Ph3C]BF4 as electrophile (Scheme 1). The reaction
using HBF4‚Et2O is faster, and it allows for easier
isolation of the product, because Ph3CCH2CHdCH2 is
difficult to separate from 1. Use of e1 equiv of HBF4‚
Et2O at 0 °C prevents formation of the undesired
dication [Ru(CH3CN)4((1,2:5,6-η)-C8H12)](BF4)2 via pro-
tonation of the allyl group in 1. We reported earlier4
that reaction between 1 and (R)-BINAP in acetone
* To whom correspondence should be addressed. E-mail:
steve.bergens@ualberta.ca.
† Current address: Achillion Pharmaceuticals, Inc., 300 George
Street, New Haven, CT 06511.
‡ Current address: Department of Chemistry, Western Washington
University, 516 High Street, Bellingham, WA 98225.
(1) (a) Noyori, R. Angew. Chem., Int. Ed. Engl. 2002, 41, 2008-2022.
(b) Noyori, R. Asymmetric Catalysis in Organic Synthesis; Wiley: New
York, 1994. (c) Noyori, R. Tetrahedron 1994, 50, 4259-4292. (d)
Takaya, H.; Ohta, T.; Noyori, R. In Catalytic Asymmetric Synthesis;
Ojima, I., Ed.; VCH: New York, 1993; Chapter 1.
(2) Dobbs, D. A.; Vanhessche, K. P. M.; Brazi, E.; Rautenstrauch,
V.; Lenoir, J .-Y.; Geneˆt, J .-P.; Wiles, J .; Bergens, S. H. Angew. Chem.,
Int. Ed. 2000, 39, 1992-1995.
(3) (a) Wiles, J . A.; Bergens, S. H., Vanhessche, K. P. M.; Dobbs, D.
A.; Rautenstrauch, V. Angew. Chem., Int. Ed. 2001, 40, 914-919. (b)
Dobbs, D. A.; Vanhessche, K. P. M.; Rautenstrauch, V. Ruthenium
Catalysts and Method for Making Same. U.S. Patent 6,455,640, 2002.
(c) Dobbs, D. A.; Vanhessche, K. P. M.; Rautenstrauch, V. Ruthenium
Catalysts and their Use in the Asymmetric Hydrogenation of Weakly
Coordinating Substrates. U.S. Patent 6,214,763, 2001.
(4) Wiles, J . A.; Lee, C. E.; McDonald, R.; Bergens, S. H. Organo-
metallics 1996, 15, 3782-3784.
(5) Bauer, A.; Englert, U.; Geyser, S.; Podewils, F.; Salzer, A.
Organometallics 2000, 19, 5471-5476.
(6) Schrock, R. R.; J ohnson, B. F. G.; Lewis, J . J . Chem. Soc., Dalton
Trans. 1974, 951-959.
10.1021/om049740x CCC: $27.50 © 2004 American Chemical Society
Publication on Web 09/02/2004

Alternate Route to Chiral Hydrogenation Catalysts
Organometallics, Vol. 23, No. 20, 2004 4565
Sch em e 1
Sch em e 4
Sch em e 2
reaction of Ru(P-P)(OAc)2 (P-P ) (6,6′-dimethoxy-
biphenyl-2,2′-diyl)bis(bis(3,5-di-tert-butylphenyl)phos-
phine), 2 HBF4, and (1,2:5,6-η)-C8H12, while the other
analogue was made by reaction of 0.5 [Ru(CF3CO2)2((1,2:
5,6-η)-C8H12)]2 with (6,6′-dimethoxybiphenyl-2,2′-diyl)-
bis(diisopropylphosphine). Other complexes containing
BINAP and related ligands coordinated to ruthenium
in this manner have been studied widely by Pregosin’s
group and other groups.11
Sch em e 3
Gen er a tion a n d Ch a r a cter iza tion of Solven to
Ca ta lysts in th e Absen ce of Su bstr a te. We reported
previously that complexes 2 and 3 react rapidly with
excess hydrogen (pressure ∼1 atm) in solutions of
acetone in the absence of substrate to yield cyclooctane12
and fac-[Ru(bisphosphine)(H)(sol)3]BF4 (sol ) acetone;
4, bisphosphine ) (R)-BINAP; 5, bisphosphine ) (R)-
Tol-BINAP; Scheme 4).3a We have found in this subse-
quent research that the hydrido-solvento complexes 4
and 5 are not stable at room temperature for prolonged
periods of time in the absence of substrate, and that the
stability of these complexes is solvent dependent. Reac-
tion of 2 with hydrogen carried out in acetone solution
at room temperature quickly produced 4 in high yield,
which then decomposed slowly over hours to generate
mixtures of unidentified species. Reaction of 2 with
hydrogen in THF solution at room temperature rapidly
produced 4 (with sol ) THF) that decomposed within
minutes. Complex 4, however, was generated in high
yield at 0 °C in THF, and it was stable at this
temperature for several hours. We found that 4 (sol )
i-PrOH) is significantly less stable in i-PrOH solutions
a solvent used commonly in catalytic ketone hydrogena-
tions13sthan in acetone or in THF. Remarkably, we
found that compound 4 can be generated in i-PrOH by
reaction with hydrogen and storage at ∼-60 °C. Com-
pound 4 began to decompose in i-PrOH solution upon
warming to -40 °C. The identity of the decomposition
resulted in activation of an allylic C-H bond of 1,5-
cyclooctadiene, and subsequent formation of propene
and two equimolar diastereomers of [Ru((R)-BINAP)-
((1-3:5,6-η)-C8H11)(CH3CN)]BF4 (8). We now report that
this approach yields the related complex [Ru((R)-Tol-
BINAP)((1-3:5,6-η)-C8H11)(CH3CN)]BF4 (9), also iso-
lated as a mixture of two equimolar diastereomers
(Scheme 2).
The acetonitrile ligand in the diastereomers of 8 is
sufficiently labile to allow exchange with excess CH3C15N
at room temperature to prepare 8-CH3C15N.7,8 This
lability suggests that the acetonitrile can be removed
by heating to generate more active acetonitrile-free
species such as 2. Indeed, heating the diastereomeric
mixtures of 8 (containing BINAP) and 9 (containing Tol-
BINAP) in n-propanol (80 °C, 2 h) resulted in loss of
the acetonitrile ligand and isomerization of the (1-3:
5,6-η)-C8H11 ligand9 to generate only one isomer of the
conjugated (1-5-η)-C8H11 species 2 and 3, respectively
(Scheme 3).
The BINAP and Tol-BINAP ligands in 2 and 3 act
formally as six-electron donors (η2,κ2-biaryl coordina-
tion) via a metal-olefin bond and two metal-phospho-
rus bonds. Two compounds analogous to 2 and 3,
[Ru((1-5-η)-C8H11)(P-P)]+, were reported in 1997 by
Pregosin and co-workers.10 One analogue was made by
(11) For examples of BINAP, BINAP-monooxide, and MeO-
BIPHEP ligands acting as six-electron donors in complexes of ruthe-
nium(II), see: (a) Hermatschweiler, R.; Pregosin, P. S.; Albinati, A.;
Rizzato, S. Inorg. Chim. Acta 2003, 354, 90-93. (b) Geldbach, T. J .;
Ru¨egger, Pregosin, P. S.; Albinati, A. Magn. Reson. Chem. 2003, 41,
703-708. (c) Geldbach, T. J .; Pregosin, P. S.; Albinati, A. Organome-
tallics 2003, 22, 1443-1451. (d) Cyr, P. W.; Rettig, S. J .; Patrick, B.
O.; J ames, B. R. Organometallics 2002, 21, 4672-4679. (e) Geldbach,
T. J .; Pregosin, P. S. Helv. Chim. Acta 2002, 85, 3937-3948. (f)
Geldbach, T. J .; den Reijer, C. J .; Wo¨rle, M.; Pregosin, P. S. Inorg.
Chim. Acta 2002, 330, 155-160. (g) Geldbach, T. J .; Pregosin, P. S.
Eur. J . Inorg. Chem. 2002, 1907-1918. (h) den Reijer, C. J .; Dotta, P.;
Pregosin, P. S.; Albinati, A. Can. J . Chem. 2001, 79, 693-704. (i) den
Reijer, C. J .; Drago, D.; Pregosin, P. S. Organometallics 2001, 20,
2982-2989. (j) den Reijer, C. J .; Wo¨rle, M.; Pregosin, P. S. Organo-
metallics 2000, 19, 309-316. (k) Feiken, N.; Pregosin, P. S.; Trabe-
singer, G.; Albinati, A.; Evoli, G. L. Organometallics 1997, 16, 5756-
5762. (l) Pathak, D. D.; Adams, H.; Bailey, N. A.; King, P. J .; White,
C. J . Organomet. Chem. 1994, 479, 237-245.
(7) Wiles, J . A.; Bergens, S. H. Organometallics 1999, 18, 3709-
3714.
(8) The lability of acetonitrile ligands in a ruthenium(II)-phosphine
complex has been demonstrated previously by ligand exchange with
CD3CN: Siedle, A. R.; Newmark, R. A.; Pignolet, L. H. Inorg. Chem.
1986, 25, 1345-1351.
(9) Thermally induced isomerizations of Ru((1-3:5,6-η)-C8H11
) to
2
generate Ru((1-6-η)-C8H10)((1,2:5,6-η)-C8H12) and of Ru((1-6-η)-C8H10)-
((1,2:5,6-η)-C8H12 to generate Ru((1-5-η)-C8H11 have been re-
)
)
2
ported: (a) Itoh, K.; Nagashima, H.; Ohshima, T.; Oshima, N.;
Nishiyama, H. J . Organomet. Chem. 1984, 272, 179-188. (b) Pertici,
P.; Vitulli, G.; Paci, M.; Porri, L. J . Chem. Soc., Dalton Trans. 1980,
1961-1964.
(12) Cyclooctane was identified and quantified by 1H NMR spec-
troscopy and by GLC (retention time confirmed by comparison to an
authentic sample).
(10) Feiken, N.; Pregosin, P. S.; Trabesinger, G.; Scalone, M.
Organometallics 1997, 16, 537-543.
(13) Ohkuma, T.; Koizumi, M.; Mun˜iz, K.; Hilt, G.; Kabuto, C.;
Noyori, R. J . Am. Chem. Soc. 2002, 124, 6508-6509.

4566 Organometallics, Vol. 23, No. 20, 2004
Wiles et al.
Ta ble 1. Ca ta lytic Hyd r ogen a tion of MACa
benchmark catalyst [Rh((R)-BINAP)(sol)2]ClO4 (7; sol )
acetone, methanol; Table 1, entries 4 and 5). The TOF
when using 7, however, was greater than when using 6
by approximately 2 orders of magnitude (approximate
TOF’s (25 °C, 1 atm of H2, acetone): 6, 0.1 min-1: 7,
9.8 min-1).18 One factor contributing to this difference
in TOF may be the presence of acetonitrile in 6.19
Indeed, use of the BINAP catalyst without an acetoni-
trile ligand in acetone (i.e., fac-[Ru((R)-BINAP)(H)(sol)3]-
BF4, sol ) acetone, 4) maintained the high enantio-
selectivity exhibited by 6 (Table 1, entries 7 and 8) while
providing TOF’s that are even slightly higher than those
of 7 (TOF of 4 (25 °C, 1 atm of H2, acetone): 11.9 min-1).
P(H2), ee,c
abs
entry
catalystb
solvent
atm
%
confign
1
2
3
4
Ru-BINAP/CH3CN (6)
Ru-BINAP/CH3CN (6)
methanol
acetone
Ru-Tol-BINAP/CH3CN (11) acetone
4
4
4
4
4
4
1
1
87
92
87
33
19
92
96
96
R
R
R
S
Rh-BINAP (7)
acetone
methanol
acetone
acetone
acetone
5
Rh-BINAP (7)
S
6
Ru-BINAP (4)
R
R
R
7d
8d
Ru-BINAP (4)
Ru-BINAP/CH3CN (6)
a
Reaction conditions: 2 mol % catalyst; [catalyst] ) 2.6 mM;
stir rate ) 1100 rpm; T ) 30 °C (except where noted otherwise).
Con clu sion s
b
Abbreviations: Ru-BINAP ) fac-[Ru((R)-BINAP)(H)(sol)3]BF4
(4), Ru-BINAP/CH3CN ) [Ru((R)-BINAP)(H)(CH3CN)n(sol)3-n]BF4
(6), Rh-BINAP ) [Rh((R)-BINAP)(sol)2]BF4 (7), and Ru-Tol-
BINAP/CH3CN ) [Ru((R)-Tol-BINAP)(H)(CH3CN)n(sol)3-n]BF4
(11). c Hydrogenations were allowed to proceed for 48 h to ensure
complete conversion of reactants to products before the absolute
configurations and the ee's of the products were determined.15,17
We described a convenient synthesis of the known
complex 1 and demonstrated its utility in the prepara-
tion of several catalyst precursors. Thermally induced
isomerization of the (1-3:5,6-η)-C8H11 ligand of 8 and
9 with loss of the acetonitrile ligand generated the
highly reactive catalyst precursors 2 and 3, respectively,
where the BINAP-type ligands functioned as six-
electron donors to the ruthenium center. Complexes 4
and 6 are the active catalysts generated quantitatively
by reaction of 2 and 8, respectively, with hydrogen.
Addition of g3 equiv of acetonitrile to 4 generated 10,
the tris(acetonitrile) species, quantitatively. Complex 4
is the most reactive (acetonitrile-free) form of 6; complex
10 is the least reactive (acetonitrile-rich) form of 6.
Complex 10 did not effect the catalytic hydrogenation
of MAC. The change of 6 to 4 as catalyst resulted in a
100-fold increase in TOF.
d
Reaction carried out at 25 °C.
product has not been determined. In contrast, Pregosin
et al. obtained the crystal structure of the sterically
crowded compound [Ru((6,6′-dimethoxybiphenyl-2,2′-
diyl)bis[3,5-di(tert-butyl)phenylphosphine])(H)(i-PrOH)2]-
BF4.14 In all solvents, complex 4 contained the hydrido
ligand in a coordination site cis to both phosphorus
centers, as shown by the magnitude of the coupling
between the phosphorus atoms and the hydride (2J P-H
typically ∼30 Hz). Further reaction with hydrogen
under these conditions was not detected by NMR
spectroscopy. Solutions of 4 did, however, react readily
with deuterium (even at -78 °C) to generate 4-d with
concomitant formation of HD. No detectable quantities
of η2-dihydrogen complexes were observed. Addition of
g3 equiv of acetonitrile to solutions containing 4 gener-
ated fac-[Ru((R)-BINAP)(H)(CH3CN)3]BF4 (10) in quan-
titative yield.
Ca ta lysis. The relative activity and enantioselectivity
of these catalysts were evaluated using a common test
reaction in enantioselective catalysis: the hydrogena-
tion of MAC. Table 1 summarizes the reactions effected
using 2 mol % 4, 6 ([Ru((R)-BINAP)(H)(CH3CN)n(sol)3-n]-
BF4; sol ) acetone, methanol, n ) 0-3), and related
complexes as catalysts. As we reported previously, there
is one CH3CN per Ru in solutions of 6, but the CH3CN
ligand exchanges rapidly among all the Ru centers in
solution at room temperature. We denote this mixture
of hydrides generally as [Ru((R)-BINAP)(H)(CH3CN)n-
(sol)3-n]BF4 (n ) 0-3).7,15 As we reported previously,15
the ee obtained using 6 as catalyst is higher in acetone
than in methanol (Table 1, entries 1 and 2). The ee
obtained in methanol is comparable to values reported
for other ruthenium-((R)-BINAP) catalysts.16
Exp er im en ta l Section
Gen er a l Com m en ts. Details describing our synthetic
techniques, analytical techniques, analytical instrumentation,
and purification of solvents appear elsewhere.15,17,20 All re-
agents were used as received from Aldrich, except (R)-BINAP,
which was purchased from Strem and recrystallized by
established procedures before use.21 (Z)-Methyl R-acetamido-
cinnamate,15 [RuCl2((1,2:5,6-η)-C8H12)]n,22 Ru((1-3-η)-C3H5)2-
((1,2:5,6-η)-C8H12),22 and [Rh(bicyclo[2.2.1]hepta-2,5-diene)((R)-
16b
BINAP)]ClO4
were prepared as described previously. The
hydrogenations of (Z)-methyl R-acetamidocinnamate and the
(16) (a) Noyori, R.; Ikeda, T.; Ohkuma, T.; Widhalm, M.; Kitamura,
M.; Takaya, H.; Akutagawa, S.; Sayo, N.; Saito, T.; Taketomi, T.;
Kumobayashi, H. J . Am. Chem. Soc. 1989, 111, 9134-9135. For the
rhodium-BINAP-catalyzed hydrogenation of the corresponding acid,
see: (b) Miyashita, A.; Takaya, H.; Souchi, T. Noyori, R. Tetrahedron
1984, 40, 1245-1253. (c) Ikariya, T.; Ishii, Y.; Kawano, H.; Arai, T.;
Saburi, M.; Yoshikawa, S.; Akutagawa, S. J . Chem. Soc., Chem.
Commun. 1985, 922-924.
(17) Wiles, J . A.; Bergens, S. H.; Young, V. G. J . Am. Chem. Soc.
1997, 119, 2940-2941.
(18) The TOF’s were determined by setting up and taking down the
pressure reactor as quickly as possible during a hydrogenation and
judging the extent of the reaction by 1H NMR spectroscopy. Their
values are to be taken as approximate.
(19) (a) Shao, L.; Takeuchi, K.; Ikemoto, M.; Kawai, T.; Ogasawara,
M.; Takeuchi, H.; Kawano, H.; Saburi, M. J . Organomet. Chem. 1992,
435, 133-147. (b) Mashima, K.; Hino, T.; Takaya, H. J . Chem. Soc.,
Dalton Trans. 1992, 2099-2107. (c) Murahashi, S.-I.; Naota, T.; Ito,
K.; Maeda, Y.; Taki, H. J . Org. Chem. 1987, 52, 4319-4327.
(20) (a) Wiles, J . A.; Bergens, S. H.; Young, V. G., J r. Can. J . Chem.
2001, 79, 1019-1025. (b) Daley, C. J . A.; Wiles, J . A.; Bergens, S. H.
Can. J . Chem. 1998, 76, 1447-1456.
Catalyst 11 ([Ru((R)-Tol-BINAP)(H)(CH3CN)n(sol)3-n]-
BF4; sol ) acetone) was less enantioselective than the
BINAP catalyst 6 in acetone (Table 1, entry 3). Notably,
the enantioselectivities of 6 and 11 are significantly
higher, with the opposite face selection, than that of the
(14) Currao, A.; Feiken, N.; Macchioni, A.; Nesper, R.; Pregosin, P.
S.; Trabesinger G. Helv. Chim. Acta 1996, 79, 1587-1591.
(15) Wiles, J . A.; Bergens, S. H. Organometallics 1998, 17, 2228-
2240.
(21) Takaya, H.; Akutagawa, S.; Noyori, R. In Organic Syntheses;
Smart, B. E., Ed.; Wiley: New York, 1989; Vol. 67, pp 20-32.
(22) Albers, M. O.; Singleton, E.; Yates, J . E. In Inorganic Syntheses;
Kaesz, H. D., Ed.; Wiley: New York, 1989; Vol. 26, pp 249-258.

Alternate Route to Chiral Hydrogenation Catalysts
Organometallics, Vol. 23, No. 20, 2004 4567
(m, 1H), 3.46 (m, 2H), 3.91 (m, 1H), 4.84 (m, 1H), 5.02 (m,
1H), 5.7-8.6 (aromatic). 13C{1H} NMR (100.6 MHz, CD2Cl2,
25 °C): δ 4.8 (br, CH3CN*), 5.0 (s, CH3CN), 20.5 (br, C-4*),
21.0 (s, C6H4CH3), 21.1 (s, C6H4CH3), 21.2 (s, C-4), 21.4 (s, 2 ×
C6H4CH3 overlapping), 24.9 (d, J P-C ) 3.5 Hz, C-8), 25.4 (d,
J P-C ) 5.5 Hz, C-7*), 30.5 (s, C-3), 31.6 (s, C-8*), 35.6 (d, J P-C
) 7.0 Hz, C-7), 36.2 (d, J P-C ) 9.0 Hz, C-3*), 55.5 (br, C-1*),
62.5 (br, C-5*), 66.2 (s, C-1), 70.8 (d, J P-C ) 26.5 Hz, C-5), 85.4
(s, C-2), 90.0 (br, C-2*), 98.8 (br, C-6*), 116.3 (d, J P-C ) 9.0
Hz, C-6), 122-142 (aromatic, CH3CN, and CH3CN*). 31P{1H}
F igu r e 1. Illustration of the numbering schemes for the
(1-3:5,6-η)-C8H11 and (1-5-η)-C8H11 ligands.
determination of ee and yield were carried out as we described
previously.15,17
cis-[Ru (CH3CN)2((1-3-η)-C3H5)((1,2:5,6-η)-C8H11)]BF4 (1).
A diethyl ether solution (54 wt %) of tetrafluoroboric acid (318
µL, 2.31 mmol) was added to a stirred solution of freshly
sublimed Ru((1-3-η)-C3H5)2((1,2:5,6-η)-C8H12) (748.0 mg, 2.57
mmol, sublimed under dynamic vacuum (ca. 0.05 mmHg) at
70 °C) in diethyl ether (5.0 mL) and acetonitrile (5.0 mL) at 0
°C. The resulting yellow solution was stirred for 5 min at 0 °C
and stirred an additional 2 min while warming to room
temperature. The reaction mixture was evaporated under
reduced pressure, and the resulting yellow residue was washed
with diethyl ether (5 × 5.0 mL) to remove excess Ru((1-3-η)-
C3H5)2((1,2:5,6-η)-C8H12). Slow addition of diethyl ether (5.0
mL over a 2 h period) to a saturated solution of the crude
product in acetonitrile (1.3 mL) afforded yellow, highly air-
sensitive microcrystals. The product was washed with diethyl
ether (3 × 5.0 mL) and dried in vacuo to yield 631.8 mg of 1
(65% yield based on tetrafluoroboric acid). The typical yield
for this procedure is ∼70%. The NMR spectra of this material
were identical with those reported in the literature for 1.6
[Ru ((R)-BINAP )((1-3:5,6-η)-C8H11)(CH3CN)]BF4 (8). This
compound was prepared as described previously,4 with the only
procedural improvement being recrystallization from acetoni-
trile/diethyl ether. Yield of 8‚0.4Et2O: 90%. The amended
spectroscopic data are listed below; the asterisks (*) denote
resonances attributed to the labile diastereomer. The number-
ing schemes for the cyclooctadienyl ligands in 2, 3, 8, and 9
2
NMR (161.9 MHz, CD2Cl2, 25 °C): δ 31.1 (d, J P-P ) 33.5 Hz,
2
2
1P), 34.0 (br d, J P-P ) 38.5 Hz, 1P*), 43.9 (br d, J P-P ) 38.5
2
Hz, 1P*), 45.2 (d, J P-P ) 33.5 Hz, 1P). MS (ESI): m/z calcd
for C58H54NP2102Ru ([M - BF4]+), 928.3; found, 928.3. Anal.
Calcd for C58H54BF4NP2Ru‚0.8Et2O‚0.3CH2Cl2: C, 67.17; H,
5.74; N, 1.27; Cl, 1.93. Found: C, 66.98; H, 5.55; N, 1.48; Cl,
2.13.
[Ru ((R)-BINAP )((1-5-η)-C8H11)]BF 4 (2). Complex 8 (100.7
mg, 0.105 mmol) was dissolved partially in n-propanol (40.0
mL) under an atmosphere of argon. The reactor was sealed,
and the mixture was stirred with heating (80 °C) for 40 min
to generate an amber solution. The solvent was removed under
reduced pressure with heating (80 °C) to give a yellow solid.
The solid was heated (80 °C) under vacuum for a total of 2 h.
The solid was passed quickly through a plug of neutral
alumina (Brockman I) under nitrogen using methylene chlo-
ride as eluent. Slow addition of n-pentane (80 mL) to a solution
(2.0 mL) of the recovered solid in methylene chloride afforded
a yellow powder that was collected by filtration, washed with
n-pentane (2 × 20 mL), and dried in vacuo to yield 57.8 mg
(60%) of 2 as an amber yellow microcrystalline powder. 1H
NMR (599.9 MHz, CD2Cl2, 25 °C): δ -0.15 (apparent q, J )
15.0 Hz, 1H, exo H-7), 0.07 (apparent t, J ) 15.0 Hz, 1H, H-6),
0.84 (apparent t, J ) 15.0 Hz, 2H, overlapping H-4 and endo
H-7), 1.00 (br, 1H, H-6′), 1.54 (apparent t, J ) 15.0 Hz, 1H,
H-8), 1.86 (br, 1H, H-8′), 2.20 (br, 1H, H-5), 4.65 (br, 1H, H-1),
5.46 (br, 2H, overlapping H-2 and H-3), 6.0-8.3 (aromatic).
13C{1H} NMR (100.6 MHz, CD2Cl2, 25 °C): δ 18.9 (s, C-7), 23.2
1
are illustrated in Figure 1. H NMR (400.1 MHz, CD2Cl2, 25
°C): δ -0.21 (m, 1H, H-7*), 1.05 (m, 1H, H-7′*), 1.41 (m, 1H,
H-8*), 1.6-1.9 (m, 2H, H-8′* and H-8), 1.73 (s, 3H, CH3CN*),
1.95 (m, 4H, H-8′ and CH3CN), 2.16 (m, 1H, H-4), 2.4-2.6 (m,
3H, H-3*, H-4*, and H-7), 2.69 (m, 1H, H-4′), 2.87 (m, 1H,
H-7′), 3.17 (m, 2H, H-1 and H-5), 3.26 (m, 2H, H-2* and H-4′*),
3.40 (m, 1H, H-3), 3.53 (m, 2H, H-2 and H-5*), 3.95 (m, 1H,
H-1*), 4.89 (m, 1H, H-6*), 5.08 (m, 1H, H-6), 5.6-8.1 (aro-
matic). 13C{1H} NMR (100.6 MHz, CD2Cl2, 25 °C): δ 4.8 (s,
CH3CN*), 4.9 (s, CH3CN), 20.6 (s, C-4*), 21.2 (s, C-4), 24.9 (s,
C-8), 25.3 (s, C-7*), 31.1 (s, C-3), 31.6 (s, C-8*), 35.6 (s, C-7),
36.7 (d, J P-C ) 14.5 Hz, C-3*), 55.8 (s, C-1*), 62.9 (s, C-5*),
66.2 (s, C-1), 71.2 (d, J P-C ) 27.5 Hz, C-5), 85.4 (s, C-2), 90.0
(s, C-2*), 99.3 (d, J P-C ) 12.0 Hz, C-6*), 117.3 (d, J P-C ) 8.5
Hz, C-6), 125-142 (aromatic, CH3CN, and CH3CN*). 31P{1H}
(d, J P-C ) 2.0 Hz, C-6), 27.3 (s, C-8), 58.5 (apparent t, J P-C
)
3.5 Hz, C-1), 64.0 (d, J P-C ) 35.0 Hz, BINAP C-2), 71.6 (dd,
J P-C ) 20.0, 2.0 Hz, C-5), 91.0 (s, C-2), 96.2 (s, C-4), 97.8 (dd,
J P-C ) 5.5, 4.0 Hz, BINAP C-1), 114.1 (d, J P-C ) 9.5 Hz, C-3),
123-148 (aromatic). 31P{1H} NMR (161.9 MHz, CD2Cl2, 25
2
2
°C): δ -6.0 (d, J P-P ) 44.5 Hz, 1P), 63.9 (d, J P-P ) 44.5 Hz,
1P). HRMS (ESI): m/z calcd for C52H43P2102Ru ([M - BF4]+),
831.1884; found, 831.1883. Anal. Calcd for C52H43BF4P2Ru: C,
68.01; H, 4.72. Found: C, 67.26; H, 4.82.
[Ru ((R)-Tol-BINAP )((1-5-η)-C8H11)]BF 4 (3). Complex 9
(46.7 mg, 0.046 mmol) was dissolved partially in n-propanol
(18.7 mL) under an atmosphere of nitrogen. The reactor was
sealed, and the mixture was stirred with heating (80 °C) for
40 min to generate an amber solution. The solvent was
removed under reduced pressure with heating (80 °C) to give
a mustard yellow solid. The solid was heated (80 °C) under
vacuum for a total heating time of 2 h. The solid was passed
quickly through a plug of neutral alumina (Brockman I) under
nitrogen using methylene chloride as eluent. Addition of
hexanes (100 mL) to a solution (2.0 mL) of the recovered solid
in methylene chloride afforded a mustard yellow powder that
was collected by filtration, washed with hexanes (2 × 20 mL),
and dried in vacuo to yield 33.9 mg (75%) of 3 as an amber
yellow microcrystalline powder. 1H NMR (400.1 MHz, CD2-
Cl2, 27 °C): δ -0.19 (apparent q, J ) 13.5 Hz, 1H), 0.14
(apparent t, J ) 14.5 Hz, 1H), 1.73 (s, 3H), 2.42 (s, 3H), 2.41
(s, 3H), 2.53 (s, 3H), 4.53 (br, 1H), 5.28-5.38 (m, 2H), 5.41
(td, J ) 7.0, 2.0 Hz, 1H), 5.80 (dd, J ) 8.0, 2.0 Hz, 2H), 5.91
(d, J ) 9.0 Hz, 1H), 6.10-6.19 (m, 2H), 7.10-7.63 (m, 24H),
7.78 (d, J ) 7.0 Hz, 1H), 7.97 (d, J ) 8.0 Hz, 1H), 8.08-8.17
(m, 2H). 13C{1H} NMR (100.6 MHz, CD2Cl2, 27 °C): δ 19.0 (s,
C-7), 20.9 (s, CH3), 21.5 (s, CH3), 21.6 (s, 2 overlapping CH3),
23.1 (d, J P-C ) 2.5 Hz, C-6), 27.3 (s, C-8), 58.8 (s, C-1), 64.1 (d,
2
NMR (161.9 MHz, CD2Cl2, 25 °C): δ 32.8 (d, J P-P ) 33.5 Hz,
2
1P, P(A)), 35.7 (br d, J P-P ) 38.5 Hz, 1P, P(A′)*), 45.6 (br d,
2J P-P ) 38.5 Hz, 1P, P(B′)*), 46.9 (d, 2J P-P ) 33.5 Hz, 1P, P(B)).
MS (ESI): m/z calcd for C54H46NP2102Ru ([M - BF4]+), 872.2;
found, 872.2. Anal. Calcd for C54H46BF4NP2Ru‚0.4Et2O: C,
67.56; H, 5.10; N, 1.42. Found: C, 67.21; H, 4.92; N, 1.54.
[Ru ((R)-Tol-BINAP )((1-3:5,6-η)-C8H11)(CH3CN)]BF4 (9).
The method used for the preparation of 9 was the same as
that used for 8,4 with substitution of (R)-Tol-BINAP for (R)-
BINAP. The crude product was purified by recrystallization
from a methylene chloride/diethyl ether solvent mixture.
Yield: 75%. NMR spectroscopic data indicated that 9 was
isolated as a solvated mixture (9‚0.8Et2O‚0.3CH2Cl2) of a labile
and a nonlabile diastereomer in a ratio of 1:1. The asterisks
(*) denote resonances attributed to the labile isomer. 1H NMR
(400.1 MHz, CD2Cl2, 25 °C): δ -0.10 (m, 1H), 1.06 (m, 1H),
1.40 (m, 1H), 1.5-2.0 (m, 3H), 1.76 (br s, 3H, CH3), 1.95 (br s,
3H, CH3), 1.97 (s, 3H, CH3), 1.98 (s, 3H, CH3), 2.0-2.3 (m,
1H,), 2.13 (s, 3H, CH3), 2.16 (br s, 3H, CH3), 2.3-2.6 (m, 3H),
2.43 (s, 3H, CH3), 2.44 (s, 3H, CH3), 2.48 (s, 6H, 2 × CH3
overlapping), 2.67 (m, 1H), 2.84 (m, 1H), 3.19 (m, 4H), 3.36

4568 Organometallics, Vol. 23, No. 20, 2004
Wiles et al.
J P-C ) 35.0 Hz, Tol-BINAP C-2), 71.3 (d, J P-C ) 20.0 Hz, C-5),
91.1 (s, C-2), 95.8 (s, C-4), 97.0 (br d, J P-C ) 10.0 Hz, Tol-
light yellow-orange solution. 1H NMR (400.1 MHz, acetone-
d6, 0 °C): δ -19.95 (apparent t, J P-H ) 31.0 Hz, 1H, Ru-H),
2
BINAP C-1), 113.8 (d, J P-C ) 9.2 Hz, C-3), 120-148 (aromatic).
1.88 (s, 3H, CH3), 1.90 (s, 3H, CH3), 2.32 (s, 3H, CH3), 2.36 (s,
3H, CH3), 6.19 (d, J ) 8.5 Hz, 1H), 6.30 (d, J ) 8.5 Hz, 1H),
6.45 (m, 4H), 6.80 (apparent t, J ) 7.0 Hz, 1H), 6.90 (apparent
t, J ) 8.5 Hz, 1H), 7.21-7.39 (m, 11H), 7.57-7.73 (m, 7H),
7.86 (d, J ) 8.5 Hz, 1H), 7.95 (m, J ) 8.5 Hz, 1H). Free
2
31P{1H} NMR (161.9 MHz, CD2Cl2, 27 °C): δ -8.4 (d, J P-P
)
2
44.5 Hz, 1P), 64.1 (d, J P-P ) 45.0 Hz, 1P). HRMS (ESI): m/z
calcd for C56H51P2102Ru ([M - BF4]+), 887.2510; found, 887.2511.
Anal. Calcd for C56H51BF4P2Ru: C, 69.07; H, 5.28. Found: C,
68.01; H, 5.33.
1
cyclooctane was observed in the H NMR spectrum at ca. 1.5
fa c-[Ru ((R)-BINAP )(H)(sol)3]BF 4 (4; sol ) Aceton e-d 6).
Complex 2 (16.0 mg, 1.74 × 10-5 mol) was dissolved in acetone-
d6 (0.6 mL) and reacted with hydrogen, as outlined above for
the synthesis of 11 (sol ) acetone-d6). 1H NMR (400.1 MHz,
acetone-d6, 25 °C): δ -19.80 (apparent t, 2J P-H ) 30.5 Hz, Ru-
H), 6.0-8.5 (aromatic). Free cyclooctane was observed in the
1H NMR spectrum at ca. 1.5 ppm. 31P{1H} NMR (161.9 MHz,
ppm. 31P{1H} NMR (161.9 MHz, acetone-d6, 0 °C): δ 70.2 (d,
2
2J P-P ) 50.5 Hz, 1P), 78.2 (d, J P-P ) 50.5 Hz, 1P).
fa c-[Ru ((R)-Tol-BINAP )(H)(sol)3]BF 4 (5; sol ) THF -d 8).
Complex 3 (8.5 mg, 8.7 × 10-6 mol) was dissolved in THF-d8
(0.7 mL) and reacted with hydrogen at 0 °C as outlined above.
NMR spectroscopic data collected at 0 °C indicated that the
resulting orange solution contained
5 and a product of
2
acetone-d6, 25 °C): δ 71.2 (d, J P-P ) 49.5 Hz, 1P), 79.7 (d,
decomposition (∼12%). 1H NMR (400.1 MHz, THF-d8, 0 °C):
δ -23.5 (apparent t, 2J P-H ) 31.0 Hz, 1H, Ru-H), 1.89 (s, 3H,
CH3), 1.90 (s, 3H, CH3), 2.33 (s, 3H, CH3), 2.37 (s, 3H, CH3),
6.37 (d, J ) 8.5 Hz, 2H), 6.48 (m, 2H), 6.80 (apparent t, J )
7.5 Hz, 2H), 6.89 (apparent, J ) 7.5 Hz, 2H), 7.10-7.23 (m,
6H), 7.40-7.48 (m, 4H), 7.54 (d, J ) 7.6 Hz, 2H), 7.66 (d, J )
8.8 Hz, 2H), 7.75-7.83 (m, 4H), 7.96 (m, 2H). Free cyclooctane
was observed in the 1H NMR spectrum at ca. 1.5 ppm. 31P-
2J P-P ) 49.5 Hz, 1P).
fa c-[Ru ((R)-BINAP )(H)(sol)3]BF 4 (4; sol ) THF -d 8).
Complex 2 (7.5 mg, 8.17 × 10-6 mol) was dissolved in THF-d8
(0.7 mL) in an NMR tube under an atmosphere of argon. The
tube was cooled to 0 °C, injected with 10 mL of hydrogen using
a gastight syringe, and shaken periodically over 30 min
(maintaining the temperature of the reaction mixture ∼0 °C)
to generate a yellow-orange solution. 1H NMR (400.1 MHz,
THF-d8, 0 °C): δ -23.26 (br, Ru-H), 6.0-8.5 (aromatic). Free
2
{1H} NMR (161.9 MHz, THF-d8, 0 °C): 48.0 (d, J P-P ) 42.0
2
Hz, dec), 61.5 (d,2J P-P ) 42.0 Hz, dec), 73.7 (d, J P-P ) 51.0
1
2
cyclooctane was observed in the H NMR spectrum at ca. 1.5
Hz, 1P), 80.2 (d, J P-P ) 51.0 Hz, 1P).
ppm. 31P{1H} NMR (161.9 MHz, THF-d8, 0 °C): δ 75.0 (d, 2J P-P
fa c-[Ru ((R)-Tol-BINAP )(H)(sol)3]BF 4 (5; sol ) i-P r OH-
d 8). Complex 3 (9.2 mg, 9.4 × 10-6 mol) was dissolved in a
mixture of CD2Cl2 (0.2 mL) and i-PrOH-d8 (0.5 mL) in an NMR
tube under an atmosphere of argon. This mixture was reacted
with hydrogen at -60 °C as outlined above for 4, with sol )
i-PrOH-d8. NMR spectra collected at -60 °C showed that the
resulting orange solution contained 5 and ∼10% of unknown
decomposition products. 1H NMR (400.1 MHz, CD2Cl2/i-PrOH-
d8, -60 °C): δ -24.2 (br, Ru-H), 1.77 (s, 3H, CH3), 1.83 (s,
3H, CH3), 2.30 (s, 3H, CH3), 2.33 (s, 3H, CH3), 6.0-8.5
(aromatic). The decomposition products had broad signals at
-0.89 and -10.6 ppm. Free cyclooctane was observed in the
1H NMR spectrum at ca. 1.5 ppm. 31P{1H} NMR (161.9 MHz,
2
) 51.5 Hz, 1P), 81.6 (d, J P-P ) 51.5 Hz, 1P).
fa c-[Ru ((R)-BINAP )(H)(sol)3]BF 4 (4; sol ) i-P r OH-d 8).
Complex 2 (13.1 mg, 1.43 × 10-5 mol) was dissolved in a
mixture of CD2Cl2 (0.2 mL) and i-PrOH-d8 (0.5 mL) in an NMR
tube under an atmosphere of argon. The tube was cooled to
-60 °C and injected with 8 mL of hydrogen using a gastight
syringe. The tube was then removed briefly from the cooling
bath, shaken vigorously, and returned to the bath in order to
maintain the temperature near -60 °C. NMR spectra collected
at -50 °C showed that the resulting orange solution contained
4 and ∼10% of unknown decomposition products. 1H NMR
(400.1 MHz, CD2Cl2/i-PrOH-d8, -50 °C): δ -23.6 (br, Ru-H),
6.0-8.5 (aromatic). The decomposition products had broad
signals at -0.86 and -10.6 ppm. Free cyclooctane was
observed in the 1H NMR spectrum at ca. 1.5 ppm. 31P{1H}
NMR (161.9 MHz, CD2Cl2/i-PrOH-d8, -50 °C): δ 73.9 (d, 2J P-P
) 49.0 Hz, 1P), 88.9 (br, 1P). The decomposition products had
signals at 37.5, 49.1, 53.9, and 61.3 ppm.
2
CD2Cl2/i-PrOH-d8, -60 °C): δ 72.0 (d, J P-P ) 47.5 Hz, 1P),
89.1 (br, 1P). The decomposition products had signals at 35.8,
48.1, and 58.9 ppm.
Ack n ow led gm en t. This work was supported by the
Natural Sciences and Engineering Research Council of
Canada and by the University of Alberta. We sincerely
appreciate the expert assistance of the University of
Alberta High Field NMR Laboratory.
fa c-[Ru ((R)-Tol-BINAP )(H)(sol)3]BF 4 (5; sol ) Aceton e-
d 6). Complex 3 (8.9 mg, 9.1 × 10-6 mol) was dissolved in
acetone-d6 (0.7 mL) in an NMR tube under an atmosphere of
argon. The tube was cooled to 0 °C, injected with 10 mL of
hydrogen using a gastight syringe, and shaken to generate a
OM049740X