Palladium(II), platinum(II), and iridium(I) complexes of 2-phosphino-1-dimethylaminoferrocenes: A survey of structure and catalysis

Article abstract of DOI:10.1021/om900422t

A series of PdCl₂, PtCl₂, and Ir(COD)BAr_F complexes bearing a rare class of racemic bidentate 2-phosphino-1- dimethylaminoferrocene ligands were prepared and characterized by NMR spectroscopy and X-ray crystallography. The

Full text of DOI:10.1021/om900422t

4534 Organometallics 2009, 28, 4534–4543
DOI: 10.1021/om900422t
Palladium(II), Platinum(II), and Iridium(I) Complexes of 2-Phosphino-1-
dimethylaminoferrocenes: A Survey of Structure and Catalysis
Costa Metallinos,* Josh Zaifman, Lori Van Belle, Laura Dodge, and Melanie Pilkington
Department of Chemistry, Brock University, 500 Glenridge Avenue, St. Catharines, Ontario L2S 3A1,
Canada
Received May 21, 2009
A series of PdCl2, PtCl2, and Ir(COD)BArF complexes bearing a rare class of racemic bidentate
2-phosphino-1-dimethylaminoferrocene ligands were prepared and characterized by NMR spec-
troscopy and X-ray crystallography. The new complexes displayed a structural trend relating a
decrease in heteroatom-metal bond length with an increase in ligand bite angle on going from Ir to
Pd and Pt. The PdCl2 and PtCl2 complexes were almost isostructural and featured MCl2 moieties in
the plane of the substituted Cp ring of the ligand. In contrast, the Ir(COD)þ complex was
distinguished by a bend of the Ir(COD) moiety toward the unsubstituted (Cp0) ring. The latter gave
rise to a steric interaction that placed the Cp rings in almost eclipsed conformations. Ligand 8a
(2-diphenylphosphino-1-dimethylaminoferrocene) was able to promote Pd-catalyzed Suzuki-
Miyaura and Buchwald-Hartwig coupling of aryl chlorides in addition to Ir-catalyzed hydrogena-
tion of electron-deficient and unactivated alkenes. A preliminary intramolecular hydroamination of
a terminal alkene using 8a in conjunction with Ir(I) afforded the cyclized product in 64% yield.
Introduction
enantioselective processes such as hydrogenation of prochir-
al alkenes,3 for which PHOX ligands4,5 of general structure
2 are among the most effective (Figure 1). Among ferrocenes,
countless P,N ligands derived from Ugi’s chiral (dimethyla-
minomethyl)ferrocenes6 (e.g., 37), oxazolines8 (4), and sulf-
oxides9 (e.g., 5) have been investigated, but these often
feature ligating heteroatoms in pendant groups and/or het-
erocyclic rings and usually contain additional stereogenic
centers. Only recently have there been reports of exclusively
planar chiral ferrocenyl P,N ligands in which both heteroa-
toms are directly attached to the cyclopentadienyl (Cp) ring.
These include the racemic indenyl derivative 6 by Stradiot-
to10 and the C2-symmetric diphosphine 7 by Alonso et al.11
The lack of examples of these types of P,N ligands may
partially reflect limitations of established synthetic routes to
aminoferrocenes, although some creative efforts have been
aimed at solving these problems.12
Ligands containing both nitrogen and phosphorus donor
groups figure prominently in many synthetically important
transformations mediated by transition metals. These cata-
lytic reactions range from achiral processes such as arylation
and amination of aryl chlorides with biaryls such a 1,1,2 to
*Corresponding author. E-mail: cmetallinos@brocku.ca.
(1) Old, D. W.; Wolfe, J. P.; Buchwald, S. L. J. Am. Chem. Soc. 1998,
120, 9722.
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2008, 47, 6338. (b) Martin, R.; Buchwald, S. L. Acc. Chem. Res. 2008, 41,
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Res. 1998, 31, 805. (d) Buchwald, S. L.; Jiang, L. In Metal-Catalyzed
Cross-Coupling Reactions; de Meijere, A., Diederich, F., Eds.; Wiley-VCH:
Weinheim, 2004; p 699. (e) Muci, A. R.; Buchwald, S. L. Top. Curr. Chem.
2002, 219, 131. (f ) Hartwig, J. F. Acc. Chem. Res. 1998, 31, 852. (g)
Hartwig, J. F. Synlett 1997, 329. (h) Hartwig, J. F. Synlett 2006, 1283. (i)
Hartwig, J. F. Angew. Chem., Int. Ed. 1998, 37, 2046. ( j) Hartwig, J. F. In
Handbook of Organopalladium Chemistry for Organic Synthesis; Wiley-
Interscience: New York, 2002; p 1051. (k) Hartwig, J. F. In Modern Arene
Chemistry; Astruc, P., Ed.; Wiley-VCH: Weinheim, 2002; p 107. (l) Hartwig,
J. F. In Comprehensive Coordination Chemistry II, Vol. 9; Ward, M. D.,
Ed.; Elsevier: Amsterdam, 2003; p 369. (m) Hartwig, J. F. In Modern
Amination Methods; Ricci, A., Ed.; Wiley-VCH: Weinheim, 2000; p 195.
(n) Hartwig, J. F. Acc. Chem. Res. 2008, 41, 1534.
(5) For asymmetric reduction of imines using PHOX-like aminopho-
sphines, see: Cahill, J. P.; Lightfoot, A. P.; Goddard, R.; Rust, J.; Guiry,
P. J. Tetrahedron: Asymmetry 1998, 9, 4307.
(6) Marquarding, D.; Klusacek, H.; Gokel, G.; Hoffmann, P.; Ugi, I.
J. Am. Chem. Soc. 1970, 92, 5389.
(7) Pioda, G.; Togni, A. Tetrahedron: Asymmetry 1998, 9, 3903.
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116.
(10) Wechsler, D.; Rankin, M. A.; McDonald, R.; Ferguson, M. J.;
Schatte, G.; Stradiotto, M. Organometallics 2007, 26, 6418.
(11) Alonso, J.; Lindenschmidt, A.; Nazare, M.; Halland, N.; Rkyek,
O.; Umann, M. Eur. Pat. Appl. 1878724, 2008.
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(3) (a) Bell, S.; Wustenberg, B.; Kaiser, S.; Menges, F.; Netscher, T.;
Pfaltz, A. Science 2006, 311, 642. (b) W€ustenberg, B.; Pfaltz, A. Adv.
Synth. Catal. 2008, 350, 174. (c) Lu, W.-J.; Chen, Y.-W.; Hou, X.-L. Angew.
Chem., Int. Ed. 2008, 47, 10133. (d) Li, S.; Zhu, S.-F.; Zhang, C.-M.; Song,
S.; Zhou, Q.-L. J. Am. Chem. Soc. 2008, 130, 8584. (e) Zhou, J.; Burgess, K.
Angew. Chem., Int. Ed. 2007, 46, 1129.
(4) Reviews: (a) Roseblade, S. J.; Pfaltz, A. Acc. Chem. Res. 2007, 40,
1402. (b) Pfaltz, A.; Blankenstein, J.; Hilgraf, R.; Hormann, E.; McIntyre, S.;
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Menges, F.; Schonleber, M.; Smidt, S. P.; W€ustenberg, B.; Zimmermann, N.
Adv. Synth. Catal. 2003, 345, 33. (c) Church, T. L.; Andersson, P. G. Coord.
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r
pubs.acs.org/Organometallics
Published on Web 07/08/2009
2009 American Chemical Society

Article
Organometallics, Vol. 28, No. 15, 2009 4535
Figure 1. P,N ligands with applications in cross-coupling (1, 7), aryl amination (1), hydroamination (1), hydrogenation (2, 4),
hydrosilylation (3), allylic substitution (5), and hydroboration (6).
Recently we reported an alternate and potentially more
Scheme 1. Preparation of Aminophosphines 8a and 8b
direct synthesis of planar chiral 1,2-P,N-ferrocenes (e.g., 8a)
by boron trifluoride activated lithiation of dimethylamino-
ferrocene.13 An enantioselective variant of this process is
currently under investigation in our laboratories and will be
reported in due course.14 In the meantime, we were interested
in examining in more detail the coordination behavior of
these ligands with catalytically important transition metals.
In this paper we investigate the coordination chemistry of
racemic ligands of this series toward the square-planar
metals Pd(II), Pt(II), and Ir(I), determine their structures
by X-ray crystallography, and study their catalytic potential
in a number of transformations including Suzuki-Miyaura
or Buchwald-Hartwig coupling of aryl chlorides, hydroge-
nation or hydroamination of alkenes.
Results and Discussion
Scheme 2. Synthesis of Pd, Pt, and Ir Complexes
Synthesis of Ligands and Complexes. Following our pub-
lished procedure,13 dimethylaminoferrocene (9) was reacted
with boron trifluoride etherate in tetrahydrofuran to give a
yellow zwitterion (10) that was cooled to -40 °C and treated
with n-BuLi (Scheme 1). The resulting red-orange 2-lithio-
ferrocene was quenched with two different chlorophosphines
to afford diphenyl phosphine 8a and dicyclohexyl phosphine
8b in identical yields (77%). Although 8a was an air-stable
solid, compound 8b was a moderately air-sensitive oil that
was best stored under inert atmosphere.
The ability of 8a and 8b to behave as chelating ligands
toward square-planar transition metals was tested initially
with Pd(II). Addition of 8a or 8b to a solution of Pd
(CH3CN)2Cl2 in dichloromethane at room temperature
afforded the coordination complexes 11a,b in excellent yields
as orange or rust-colored solids, respectively (Scheme 2).
Evidence of bidentate coordination was provided by 31P and
1H NMR analysis. Coordination of the phosphine moiety
was inferred by the significant downfield shift of the 31P
NMR signals of 11a (δ 25.3) and 11b (δ 51.1) compared to
the phosphorus resonances of the free ligands (8a, δ -20.4;
8b, δ -12.3). Simultaneous coordination of nitrogen would
render the amino methyl groups diastereotopic in the
complexes. This nonequivalence is indeed observed in the
1H NMR spectra as two methyl singlets for 11a (δ 3.46, 3.09)
and 11b (δ 3.47, 3.12). Only one methyl singlet is present in
(13) Metallinos, C.; Zaifman, J.; Dodge, L. Org. Lett. 2008, 10, 3527.
(14) Metallinos, C. United States Provisional Patent Application 61/
117,400, 2008.

4536 Organometallics, Vol. 28, No. 15, 2009
Table 1. Diagnostic 31P and 1H NMR Signals for 8a,b, 11a,b, 12a,b, and 13
Metallinos et al.
8a
8b
11a
11b
12a
12b
21.7
3.64, 3.26
CDCl3
13
31P NMR (δ)
1H NMR (NMe2, δ)
solvent
-20.4
2.69
CDCl3
-12.3
2.75
acetone-d6
25.3
3.46, 3.09
CDCl3
51.1
3.47, 3.12
CDCl3
2.0
3.65, 3.24
CDCl3
15.0
3.13, 2.69
CDCl3
Figure 2. ORTEP plot of 11a at 50% probability. Hydrogen
atoms are omitted for clarity.
Figure 4. ORTEP plot of 13 at 50% probability. Hydrogen
atoms and the BArF counterion are omitted for clarity.
complexes featured staggered conformations of their respec-
tive Cp rings, with dihedral angles defined by H4-C4-C40-
H40 of 32.27(14)° for 11a and 28.59(13)° for 12a. As expec-
ted for square-planar metals, the ligand displayed nearly
orthogonal bite angles (P1-Pd1-N2 and P1-Pt1-N2)
of 87.87(6)° in 11a and 88.78(5)° in 12a. The smaller bite
angle for 11a may be a consequence of the longer N1-Pd1
˚
and P1-Pd1 bond lengths (2.135(2) and 2.2185(7) A, respec-
tively) versus the N1-Pt and P1-Pt distances in 12a (2.114
(2) and 2.2066(6) A, respectively), although the differences
˚
are small. Complex 11a is also distinguished by a slight
conformational twist of the NMe2 group, which causes
the N1 atom to be slightly puckered and below the mean
plane defined by the P1, Cl1, and Cl2 atoms (deviation from
˚
plane=0.251(5) A). For comparison, the N1 atom of 12a is
nearly coplanar with the P1, Cl1, and Cl2 atoms (deviation
Figure 3. ORTEP plot of 12a at 50% probability. Hydrogen
atoms are omitted for clarity.
˚
from plane=0.091(4) A).
1
the H NMR spectra of the noncoordinated ligands (8a,
δ 2.69; 8b, δ 2.75).
Unlike 11a and 12a, where the PdCl2 and PtCl2 moieties
are in the same plane as the substituted Cp ring of the ligand,
the Ir(COD) portion of complex 13 is bent upward toward
the unsubstituted (Cp0) ring (Figure 4). This spatial prefer-
ence is most likely a result of the steric demands of the
COD ligand and results in relatively close contact distances
In a similar manner, Pt(II) complexes of 8a and 8b were
made by addition of either ligand to a solution of Pt(COD)
Cl2 in toluene at reflux to give 12a and 12b. An Ir(I) complex
of 8a was prepared from [Ir(COD)Cl]2 in refluxing dichlor-
omethane and isolated after in situ exchange of the chloride
ion with sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)bo-
rate (NaBArF) to give the BArF salt of 13 as an air-stable
orange solid. The preceding platinum and iridium complexes
displayed analogous downfield shifts of their 31P NMR
signals and diastereotopic amino methyl groups by
1H NMR, as observed for 11a,b, suggesting chelation of
the ligands to the metals. The key 31P and 1H NMR signals
for all ligands and complexes are summarized in Table 1.
Structural Studies. The apparent bidentate coordination
behavior of the new ligands was verified by X-ray crystal-
lographic analysis of 11a, 12a, and 13. Suitable crystals of
these compounds were grown from acetonitrile, acetone,
and benzene, respectively. Diffraction studies established
that the palladium and platinum complexes were almost
isostructural (Figures 2 and 3), despite the fact that they
crystallized in two different crystal systems and space groups
(11a, orthorhombic Pbca; 12a, monoclinic P21/n). Both
between H10 or H20 and H26B of COD (H10
H26B=2.68
3 3 3
0
˚
˚
(1) A; H2
H26B=2.56(1) A). The proximity of H26B to
3 303
H10 and H2 may also be responsible for the near eclipsed
conformation of the Cp rings in 13 (H4-C4-C40-H40
dihedral angle=4.53(8)°). Another factor affecting the shape
of 13 may be the pseudoaxial/pseudoequatorial arrangement
of the P-Ph groups. In the preferred conformation of the
chelate ring, the pseudoequatorial phenyl group (C6-C11) is
pointing away from the Cp0 ring. The same phenyl group
would become pseudoaxial in the alternate conformer in
which Ir(COD) is bent downward, resulting in an unfavor-
able interaction with the Cp0 ring. Beyond these interactions,
bond length and bite angle metrics of 13 continued the trend
observed with 11a and 12a. In this respect, the iridium
complex possesses the longest heteroatom-metal bonds of
the series (N1-Ir1 and P1-Ir1 bond lengths=2.225(3) and
˚
2.2951(9) A, respectively) in addition to the smallest bite
angle (N1-Ir-P1 angle = 82.84(8)°). The shape of 13 in the

Article
Organometallics, Vol. 28, No. 15, 2009 4537
Table 2. Selected X-ray Crystallographic Data for 11a, 12a, and 13
11a
12a
13
formula
mol weight (g/mol)
color
cryst size (mm)
temp (K)
cryst syst
C
590.56
24H24Cl2FeNPPd
C24H24Cl2FeNPPt
679.22
C64H48BF24FeNPIr
1576.88
orange
orange
0.24 ꢀ 0.22 ꢀ 0.18
orange
0.34 ꢀ 0.27 ꢀ 0.12
0.30 ꢀ 0.26 ꢀ 0.04
173(2)
orthorhombic
150(2)
monoclinic
150(2)
triclinic
P1
space group
˚
Pbca
17.378(3)
14.1396(18)
18.736(3)
90
90
90
4603.8(11)
8
1.704
Mo KR
1.725
2.15 to 29.00
6126 [R(int) = 0.0398]
0.7465, 0.6823
R1 = 0.0324, wR2 = 0.0831
R1 = 0.0411, wR2 = 0.0888
1.055
P21/n
9.9906(18)
14.365(3)
16.145(3)
90
90.946(6)
90
2316.7(8)
4
1.947
Mo KR
6.970
2.84 to 28.21
5807 [R(int) = 0.0237]
0.432, 0.110
R1 = 0.0148, wR2 = 0.0331
R1 = 0.0187, wR2 = 0.0347
1.068
a (A)
12.7697(6)
12.8455(6)
19.8377(10)
74.724(2)
76.026(3)
87.188(2)
3045.8(3)
2
1.719
Mo KR
2.563
2.19 to 28.48
15 144 [R(int) = 0.0341]
0.9043, 0.5133
R1 = 0.0352, wR2 = 0.0985
R1 = 0.0413, wR2 = 0.1041
1.133
˚
b (A)
˚
c (A)
R (deg)
β (deg)
γ (deg)
3
˚
V (A )
Z
Dc (g/cm3)
radiation
μ (mm-1
)
θ range (deg)
unique data
maximum, minimum transmn
final R indices [I > 2σ(I)]
R indices (all data)
goodness-of-fit on F2
-3
˚
peak/hole (e A
)
1.583/-0.468
0.523/-0.741
6.129/-0.790
solid state bears some resemblance to the crystallographi-
would provide the impetus to investigate asymmetric ver-
sions of some of these reactions with enantiomerically en-
riched ligands 8a,b in the future.14 Initial catalytic studies
using 8a,b focused on achiral palladium-mediated cross-
coupling reactions of aryl chlorides. The first test involved
Suzuki-Miyaura coupling of 4-trifluoromethylchloroben-
zene (14a) with phenylboronic acid (2 mol % 11a, 3 equiv of
CsF, dioxane, reflux), which afforded 15a in 65% yield.
Better results were realized by in situ generation of the
catalyst (2 mol % Pd(OAc)2, 4 mol % 8a, 3 equiv of CsF,
dioxane, reflux), which gave 15a in excellent 94% yield
(Scheme 3). Under these conditions, good yields were also
obtained with 4-acetyl and 4-cyano chlorobenzenes (15b,
88%; 15c, 92%). The sterically hindered 2-nitro derivative
(14d) gave 15d in 73% yield. Chlorobenzenes with electron-
donating substituents such as 4-methoxy (14e) and 4-methyl
(14f) were less reactive, resulting in lower yields of biphenyls
(15e, 70%; 15f, 56%). Replacing ligand 8a with 8b did
not improve the yields of 15e or 15f. However, the double
phenylation of quinolinyl dibromide 14g proceeded smoo-
thly under the standard reaction conditions to give 15g in
88% yield, which was significantly better than what was
obtained using Pd(PPh3)4 as the catalyst (42% yield).
Buchwald-Hartwig amination of aryl halides with mor-
pholine proved to be more challenging. While satisfactory
results were obtained with chlorides 14a and 14b, the low
reactivity of electron-rich and electron-neutral substrates
necessitated the use of the corresponding bromides (14e,h).
The latter afforded products 16e and 16h in 67% and 82%
yields, respectively. Chlorides with ortho substituents were
also sluggish to react (14d f 16d: 43%). Unlike the Suzuki-
Miyaura couplings, which worked best with a 2:1 ratio of
ligand to palladium, the Buchwald-Hartwig aminations
gave better results with a 1:1 ratio of ligand to palladium,
suggesting chelation of the ligand in the catalytically active
species. The use of a 2:1 ratio of ligand to palladium in the
aryl amination experiments resulted in very low (<5%)
yields.
cally determined structure of complex 6 Rh(COD)BF4 re-
3
ported recently by Stradiotto10 and co-workers, although the
latter has less bend of the Rh(COD) moiety due to the
presence of the bulkier pentamethylcyclopentadienyl (Cp*)
ring. A summary of other key crystallographic data for 11a,
12a, and 13 is shown in Table 2.
Catalytic Studies. The use of ligands of general structure 1
(e.g., R=Cy) in palladium-catalyzed Suzuki-Miyaura and
Buchwald-Hartwig cross-coupling of aryl chlorides is well
established.1,2 While 1 and its congeners have the potential to
act as bidentate donors, for the most part such ligands are
thought to be primarily bulky monodentate phosphines,
although evidence exists for π-interactions between the
20-aryl ring and Pd in some cases.15 Interest in ligands such
as 1 (R=t-Bu or Cy) received a boost recently by the reports
of Widenhoefer16 and Hartwig17 that they promote intra-
molecular hydroamination in excellent yields with catalytic
platinum(II)16 or rhodium(I).17 Hollis18 and Stradiotto19
have reported intramolecular hydroamination of similar
substrates catalyzed by iridium(I) complexes bearing pin-
cer-type or bidentate COD ligands, respectively. In addition,
chiral bidentate PHOX-type P,N ligands (2) have been
shown by Pfaltz, Andersson, and others to be excellent for
iridium-catalyzed enantioselective hydrogenation of unacti-
vated alkenes.3,4
The penchant of racemic ligands 8a and 8b to chelate
palladium, platinum, and iridium presented an opportunity
to survey their catalytic potential in non-stereoselective
transformations of both achiral and prochiral substrates.
Successful results with prochiral substrates, in particular,
(15) (a) Barder, T. E.; Biscoe, M. R.; Buchwald, S. L. Organometallics
2007, 26, 2183. (b) Barder, T. E.; Buchwald, S. L. J. Am. Chem. Soc. 2007,
129, 12003.
(16) Bender, C. F.; Hudson, W. B.; Widenhoefer, R. A. Organome-
tallics 2008, 27, 2356.
(17) Liu, Z.; Hartwig, J. F. J. Am. Chem. Soc. 2008, 130, 1570.
(18) Bauer, E. B.; Andavan, G. T. S.; Hollis, T. K.; Rubio, R. J.; Cho,
J.; Kuchenbeiser, G. R.; Helgert, T. R.; Letko, C. S.; Tham, F. S. Org.
Lett. 2008, 10, 1175.
In contrast to palladium-catalyzed aryl aminations, hy-
drogenation of unactivated and electron-deficient alkenes
(19) Hesp, K. D.; Stradiotto, M. Org. Lett. 2009, 11, 1449.

4538 Organometallics, Vol. 28, No. 15, 2009
Metallinos et al.
Scheme 3. Palladium-Catalyzed Suzuki-Miyaura and Buchwald-Hartwig Coupling Promoted by 8a
with iridium complex 13 gave excellent results with a broad
range of substrates. Thus, stilbenes 17a,b afforded the satu-
rated products 18a,b (Scheme 4) in high yields under stan-
dard conditions (2 mol % 13, 62 bar of H2, CH2Cl2, rt). A
number of cinnamate esters (17c-e) were also hydrogenated
under the same conditions in yields ranging from 94% to
96%. Hydrogenation of chalcone (17f) resulted in chemose-
lective reduction of the alkene in 99% yield. Good results
were also obtained with imines20 (17g,h) and geraniol (17i),
the latter to give product 18i in 99% yield after reduction of
both double bonds. Hydrogenations of cyclic substrates such
as maleimide (17j), cyclohexenone (17k), and naphthoqui-
none (171) also proceeded smoothly. More challenging sub-
formed N,P-chelates with all metals, a fact that was con-
firmed by X-ray crystallographic analysis. Comparison of
the solid-state structures revealed a trend relating a decrease
in heteroatom-metal bond length with an increase in ligand
bite angle on going from Ir(I) to Pd(II) and Pt(II). The Pd(II)
and Pt(II) complexes were almost isostructural and featured
MCl2 moieties in the plane of the substituted Cp ring. In
contrast, the Ir(I) complex was distinguished by a bend of the
Ir(COD) moiety toward the Cp0 ring. The latter gave rise to a
steric interaction that placed the Cp rings in almost eclipsed
conformations.
Of the two ligands, 8a proved to be effective at promoting
Pd-mediated Suzuki-Miyaura and Buchwald-Hartwig
coupling of aryl chlorides in addition to Ir-catalyzed hydro-
genation of structurally diverse alkenes. Preliminary intra-
molecular hydroamination of terminal alkene 19 using 8a in
conjunction with Ir(I) afforded pyrrolidine 20 in 64% yield,
although the corresponding Pt(II)-mediated reaction was
poor (27%). Improvements to the hydroamination process
along with an investigation of asymmetric transformations
mediated by enantiomerically enriched ligands 8a,b are
under study in our laboratories and will be reported in due
course.14
€
strates such as chromone (17m) required addition of Hunig’s
base to the reaction mixture,21 while hydrogenation of
carvone (17n) under standard conditions resulted in chemo-
selective reduction of the exocyclic double bond.
Finally, ligands 8a,b were utilized in Pt- and Ir-catalyzed
hydroamination of aminoalkene 19 (Scheme 5). For the
platinum-catalyzed reactions, a modification of Widenhoe-
fer’s procedure16 (5 mol % PtCl2, 10 mol % 8a, diethylene
glycol, 100 °C) gave low yields (27%) of the desired pyrro-
lidine (20), which could not be improved by changing ligands
or solvents or by varying the ligand/metal ratio. The pre-
formed complexes 12a,b did not promote this reaction,
implying that chelation of 8a,b to platinum is detrimental
to its catalytic activity. In contrast, hydroamination of 19
with iridium complex 13 (2.5 mol % 13, dioxane, reflux) gave
20 in improved yield (64%) along with an intractable mixture
of byproduct of isomerization or reduction of the sub-
strate.17 This transformation may be improved by small
alterations to the ligand structure or by the use of Rh(I).17
Experimental Section
General Procedures. All reagents were purchased from com-
mercial sources and used as received unless otherwise indicated.
Tetrahydrofuran (THF) was freshly dried and distilled over
sodium/benzophenone ketyl under an atmosphere of nitrogen.
Toluene was distilled from sodium under N2. Dichloromethane
and hexane were distilled over CaH2 under an atmosphere of
nitrogen. Dioxane was distilled from LiAlH4 under argon. All
reactions were performed under argon in flame- or oven-dried
glassware using syringe-septum cap techniques or Schlenk con-
ditions unless otherwise indicated. Column chromatography
was performed on silica gel 60 (70-230 mesh) or neutral
alumina. NMR spectra were obtained on a Bruker Avance
300 or 600 MHz instrument and are referenced to TMS or to
the residual proton signal of the deuterated solvent for 1H
spectra and to the carbon multiplet of the deuterated solvent
for 13C spectra according to published values. Pressurized
reactions were performed with a Parr 4760 bomb. FT-IR spectra
were obtained on an ATI Mattson Research Series spectrometer
as KBr pellets for solids or on KBr discs for liquids. Mass
Conclusion
A series of coordination complexes of racemic 2-phosphi-
no-1-dimethylaminoferrocenes (8a,b) were readily prepared
from the square-planar metals Pd(II), Pt(II), and Ir(I).
Spectroscopic data indicated the likelihood that the ligands
(20) For iridium-catalyzed hydrogenation of imines with a ferrocenyl
P,N ligand featuring a pendant pyridyl donor, see: Cheemala, M. N.;
Knochel, P. Org. Lett. 2007, 9, 3089.
(21) Semeniuchenko, V.; Khilya, V.; Groth, U. Synlett 2009, 271.

Article
Organometallics, Vol. 28, No. 15, 2009 4539
Scheme 4. Hydrogenation of Alkenes and Imines Catalyzed by
13
Scheme 5. Intramolecular Hydroamination of 19
was treated with BF3 OEt2 (0.13 mL, 1.05 mmol). After 15 min,
3
the yellow solution was cooled to-40 °C, and n-BuLi (0.46 mL of
a 2.40 M solution in hexanes, 1.10 mmol) was added by syringe to
give an orange-red solution, which was stirred for 1 h before
ClPCy2 (0.24 mL, 1.10 mmol) was added and the mixture was
allowed to warm to room temperature. The reaction mixture was
diluted with Et2O (10 mL) and worked up with saturated aqueous
NaHCO3 solution (10 mL). The organic layer was washed with
H2O (1 ꢀ 10 mL) and brine (1 ꢀ 10 mL), dried over anhydrous
Na2SO4, and concentrated to dryness. The residue was redis-
solved in pentane and chromatographed on silica gel (25 mL),
eluting with 95:5 pentane/Et2O to give 397 mg (77%) of the
desired aminophosphine 8b as a moderately air-sensitive viscous
orange oil: Rf 0.50 (silica gel, 9:1 hexane/EtOAc); IR (CHCl3)
νmax 2920, 2848, 1489, 1446 cm-1 31P NMR (121 MHz,
;
acetone-d6) δ -12.3; 1H NMR (300 MHz, acetone-d6) δ 4.22 (s,
5H), 4.15 (t, 1H, J=1.1 Hz), 4.04 (t, 1H, J=2.3 Hz), 3.92 (t, 1H,
J=1.7 Hz), 2.75 (s, 6H), 2.49-2.41 (m, 1H), 2.00-1.93 (m, 1H),
1.92-1.81 (m, 3H), 1.77-1.67 (m, 2H), 1.67-1.61 (m, 1H),
1.61-1.52 (m, 3H), 1.50-1.20 (m, 7H), 1.20-1.06 (m, 2H),
1.06-0.97 (m, 1H), 0.90-0.79 (m, 1H); 13C NMR (75.5 MHz,
13
31
13C-
13C-
acetone-d6) δ 118.0 (d, J
=14.0 Hz), 67.5, 66.6 (d, J
C- P
P = 3.4 Hz), 63.3 (d, J C- P = 25.3 Hz), 63.2, 61.3 (d, J
31
13
31
31
13
P = 1.5 Hz), 43.9 (d, J C- P = 13.2 Hz), 35.0 (d, J
31
13
31
=
15.9 Hz), 33.2 (d, J C- P = 13.2 Hz), 32.2 (d, J C- P = 20.6
C- P
13
31
13
31
13
Hz), 30.2 (d, J C- P = 15.9 Hz), 29.5 (d, J C- P = 10.8 Hz),
31
13
31
13
31
13
29.0, 27.3 (d, J C- P = 11.8 Hz), 27.2 (d, J C- P = 6.5 Hz),
31
13
27.0 (d, J C- P=12.8 Hz), 26.8 (d, J C- P=8.3 Hz), 26.3 (d,
31
13
31
13
31
J
C- P = 15.5 Hz); EIMS (m/z (%)) 425 (Mþ, 87), 130 (62),
55 (100), 41 (94); HRMS (EI; m/z) calcd for C24H36NP56-
Fe 425.1936, found 425.1934.
2-Diphenylphosphino-1-dimethylaminoferrocene (8a). 8a was
prepared in a manner analogous to 8b: A solution of 9 (229 mg,
1.00 mmol) in THF (10 mL) was sequentially treated with
BF3 OEt2 (0.13 mL, 1.05 mmol), n-BuLi (0.45 mL, 2.45 M,
3
1.10 mmol), and Ph2PCl (0.22 mL, 1.20 mmol). Standard work-
up followed by column chromatography of the preadsorbed
product (silica gel, Et2O) gave an orange solid. Recrystallization
from Et2O afforded 8a (317 mg, 77%) as orange needles in two
crops: mp 146-148 °C (Et2O); IR (KBr) νmax 3090, 3050, 2952,
spectra were obtained on an MSI/Kratos Concept 1S mass
spectrometer. Combustion analyses were performed by Atlantic
Microlab Inc., Norcross, GA. Melting points were determined
on a Kofler hot-stage apparatus and are uncorrected. X-ray data
were collected on a Bruker APEX II CCD area detector
equipped with a Kappa goniometer and using Mo KR gra-
2840, 2780, 1494 cm-1 31P NMR (121.5 MHz, CDCl3) δ -20.4;
;
1H NMR (600 MHz, CDCl3) δ 7.55-7.52 (m, 2H), 7.39 (m, 3H),
7.28 (m, 5H), 4.20 (s, 1H), 4.13 (s, 5H), 4.10 (t, 1H, J=2.4 Hz),
3.50 (s, 1H), 2.69 (s, 6H); 13C NMR (150.9 MHz, CDCl3) δ 139.8
˚
phite-monochromated radiation, λ=0.71073 A. The structure
was solved by direct methods using SHELXTL software. The
refinement and all further calculations were carried out using
SHELXTL. The H atoms were included in calculated positions
and treated as riding atoms using SHELXL default parameters.
The non-H atoms were refined anisotropically using weighted
full-matrix least-squares on F2. A multiscan absorption correc-
tion was applied using the SADABS routine.
2-Dicyclohexylphosphino-1-dimethylaminoferrocene (8b). In a
dry round-bottom flask under argon, an ice-cold solution of
dimethylaminoferrocene 9 (229 mg, 1.00 mmol) in THF (10 mL)
13
31
13
31
(d, J C- P =11.0 Hz), 137.9 (d, J C- P =10.6 Hz), 135.3 (d,
13
13
31
31
J
128.0 (d), 127.8, 119.0 (d, J
C- P=22.6 Hz), 132.4 (d, J C- P=18.1 Hz), 129.0, 128.1 (d),
13C- P
= 18.1 Hz), 68.7, 68.5
31
31
13
31
13
(d, J C- P = 3.0 Hz), 65.9 (d, J C- P = 10.6 Hz), 65.2, 60.1,
45.5; EIMS [m/z (%)] 413 (Mþ, 100); HRMS (EI) calcd for
C24H24NP56Fe 413.0995, found 413.0991. Anal. Calcd for
C24H24NPFe: C, 69.75; H, 5.85. Found: C, 69.87; H, 5.94.
2-Diphenylphosphino-1-dimethylaminoferrocenepalladium Dichlo-
ride (11a). Representative Procedure. A solution of aminophosphine

4540 Organometallics, Vol. 28, No. 15, 2009
Metallinos et al.
8a (94 mg, 0.30 mmol) and Pd(MeCN)2Cl2 (58 mg, 0.30 mmol) in
CH2Cl2 (2 mL) was stirred at room temperature in a dry flask
under argon until TLC indicated consumption of the aminopho-
sphine (75 min). The reaction mixture was then filtered through a
pad of silica gel, eluting with 97:3 CH2Cl2/MeOH, and concen-
trated. Recrystallizationfrom acetonitrileat-20 °Cgave 11a (154
mg, 87%) as a light orange powder intwocrops:mp>225°C (dec
1434 cm-1
;
31P NMR (121 MHz, CDCl3) δ 21.7 (t, J
31P-
1
195
Pt = 1898 Hz); H NMR (600 MHz, CDCl3) δ 4.86 (t, 1H,
J=2.5 Hz), 4.57 (s, 1H), 4.46 (s, 5H), 4.00 (s, 1H), 3.65 (t, 3H, J=
14.8 Hz), 3.26 (t, 3H, J=14.3 Hz), 2.77-2.61 (m, 1H), 2.57-2.39
(m, 1H), 2.31-2.17 (m, 1H), 2.14-1.75 (m, 8H), 1.74-1.53 (m,
4H), 1.50-1.30 (m, 3H), 1.30-1.05 (m, 4H); 13C NMR (150
13
31
13
31
MHz, CDCl3) δ 129.9 (d, J C- P=17.8 Hz), 74.5 (d, J
=
C- P
at 210 °C); IR (KBr) νmax 3448, 1460, 1434 cm-1
;
31P NMR (243
52.6 Hz), 74.3 (d, J C- P=4.8 Hz), 71.5, 62.44, 59.4, 59.2 (d,
13
31
MHz, CDCl3) δ 25.3; 1H NMR (600 MHz, CDCl3) δ 8.11-8.05
(m, 2H), 7.63-7.58 (m, 1H), 7.58-7.52 (m, 4H), 7.51-7.46 (m,
1H), 7.39-7.34 (m, 2H), 4.74 (t, 1H J=2.3 Hz), 4.53 (s, 1H), 4.21
(s, 1H), 4.00 (s, 5H), 3.46 (s, 3H), 3.09 (s, 3H); 13C NMR (150
J
J
J
13
13
13
31
C- P = 8.9 Hz), 58.0, 36.1 (d, J C- P = 36.9 Hz), 33.0 (d,
13
31
31
13
31
C- P=37.6 Hz), 28.9, 28.0, 27.6 (d, J C- P=4.4 Hz), 27.0 (d,
31
C- P=11.6 Hz), 26.8 (d, J C- P=8.0 Hz), 26.6 (d, J
13
31
13
31
C- P
=
13
31
6.1 Hz), 26.5 (d, J C- P =11.9 Hz), 26.1, 25.5; FABMS (m/z
(%)) 691 (Mþ, 8), 655 (100), 616 (59), 55 (76). Anal. Calcd for
C24H24NPCl2FePd: C, 48.81; H, 4.10. Found: C, 49.04;
H, 4.09.
13
31
13
C- P
31
MHz, CDCl3) δ 134.6 (d, J C- P=11.6 Hz), 132.2 (d, J
2.2 Hz), 131.8 (d, J C- P = 10.1 Hz), 131.4 (d, J C- P = 57.8
=
13
31
13
31
13
31
13
31
Hz), 131.4 (d, J C- P = 3.1 Hz), 129.4 (d, J C- P = 67.7 Hz),
13
128.9 (d, J C- P=11.6 Hz), 128.6 (d, J C- P=12.1 Hz), 126.9
31
13
31
2-Diphenylphosphino-1-dimethylaminoferroceneiridium(COD)
BArF (13). A mixture of ligand 8a (82 mg, 0.20 mmol) and [Ir-
(COD)Cl]2 (67 mg, 0.10 mmol) in CH2Cl2 (2.1 mL) was stirred
under argon at reflux for 2 h. Sodium tetrakis(3,5-bis(trifluoro-
methyl)phenyl)borate (NaBArF, 266 mg, 0.30 mmol) and water
(2.1 mL) were then added, at which time the color changed from
orange to red. The solution was allowed to stir for 15 min, after
which the layers were separated. The aqueous layer was washed
with CH2Cl2 (3 ꢀ 5 mL), and the combined organic phase was
washed with water. The solution was concentrated almost to
dryness on a rotary evaporator and then passed through a plug
of silica gel, eluting with additional CH2Cl2. Removal of the
solvent in vacuo afforded 13 as orange flakes (296 mg, 94%).
A portion of the product was recrystallized from benzene to give
analytically pure crystals that were suitable for X-ray analysis: mp
197-198 °C (dec, benzene); IR (KBr) νmax 2958, 2925, 2891, 1610,
13
31
13
(d, J C- P=24.6 Hz), 75.2 (d, J C- P=6.1 Hz), 72.8 (d, J
31
13
31
C- P
=
13
31
56.1 Hz), 63.9, 60.3 (d, J C- P=12.3 Hz), 58.2, 54.5. FABMS
(m/z (%)) 591 (Mþ, 14), 554 (90), 518 (84), 413 (77), 292 (73), 229
(85), 214 (81), 108 (100). Anal. Calcd for C24H24NPCl2FePd: C,
48.81; H, 4.10. Found: C, 49.04; H, 4.09.
2-Dicyclohexylphosphino-1-dimethylaminoferrocenepalladium
Dichloride (11b). This was prepared on a 0.22 mmol scale in a
manner analogous to 11a to give 121 mg (91%) of rust-colored
crystals after recrystallization from acetonitrile at -20 °C: mp
>225 °C (dec at 195 °C); IR (KBr) νmax 2931, 2850, 1446 cm-1
;
31P NMR (121.5 MHz, CDCl3) δ 51.1; H NMR (300 MHz,
CDCl3) δ 4.71 (s, 1H), 4.59 (s, 1H), 4.46 (s, 5H), 4.00 (s, 1H), 3.47
(s, 3H), 3.12 (s, 3H), 2.72-2.54 (m, 1H), 2.52-2.33 (m, 1H),
2.33-2.16 (m, 2H), 2.16-1.88 (m, 5H), 1.87-1.31 (m, 10H),
1.31-1.05 (m, 3H); 13C NMR (75.5 MHz, CDCl3) δ 128.0 (d,
1
J
C- P=20.9 Hz), 74.6 (d, J C- P=5.6 Hz), 73.8, 73.3, 63.1,
1439, 1356, 1279, 1169, 1126 cm-1 31
; P NMR (121.5 MHz, CDCl3)
13
31
13
31
δ 14.95; 19F NMR (282.4 MHz, CDCl3) δ -62.34; 1H NMR (300
MHz, CDCl3) δ 7.72 (m, 10H), 7.55-7.42 (m, 12H), 5.04 (m, 1H),
4.90 (t, 1H, J=2.7 Hz), 4.56 (m, 1H), 4.41 (m, 1H), 4.31 (m, 1H),
4.08 (s, 5H), 4.05 (m, 1H), 3.51 (m, 1H), 3.13 (s, 3H), 2.69 (s, 3H),
13
31
13
31
60.4 (d, J C- P=10.6 Hz), 58.5, 56.7, 37.7 (d, J C- P=30.2 Hz),
13
35.1 (d, J C- P = 30.2 Hz), 29.0 (d, J C- P = 2.0 Hz), 28.7,
31
13
31
13
31
13
31
28.1, 28.0, 26.9 (d, J C- P =2.0 Hz), 26.7, 26.6 (d, J
=
C- P
2.9 Hz), 26.5, 26.4, 25.8, 25.4; FABMS (m/z (%)) 603 (Mþ, 8),
566 (81), 229 (100). Anal. Calcd for C24H36NPCl2FePd: C,
47.83; H, 6.02. Found: C, 47.77; H, 6.20.
2.39-2.24 (m, 4H), 2.05 (m, 1H), 1.90 (d, 2H, J=9.3 Hz), 1.75 (m,
13
13C-11
Hz), 135.0, 133.1, 132.7 (d, J C- P=11.3 Hz), 132.4, 132.3 (d,
1H); C NMR (75.5 MHz, CDCl3) δ 161.9 (q, J
B=49.8
13
31
2-Diphenylphosphino-1-dimethylaminoferroceneplatinum Di-
chloride (12a). Representative Procedure. A suspension of
aminophosphine 8a (100 mg, 0.24 mmol) and Pt(COD)Cl2 (90
mg, 0.24 mmol) in PhMe (2.5 mL) was heated at reflux until
TLC indicated consumption of the aminophosphine (1.5 h). The
solvent was removed on a rotary evaporator, and the residue was
redissolved in CH2Cl2, filtered through a pad of silica gel eluting
with 97:3 CH2Cl2/MeOH, and concentrated again under reduced
pressure. Recrystallization from acetone at -20 °C gave 12a
(82 mg, 50%) as fine orange crystals: mp >225 °C (dec at 210
13 31
J=2.3 Hz), 131.9 (d, J=1.5 Hz), 130.1, 129.8 (d, J C- P=11.3
13
Hz), 129.5 (d, J C- P=10.6 Hz), 129.0 (q, J
31
13C-19
F=272.4 Hz), 124.3 (d, J C- P=22.7 Hz),
13 31
F=29.4 Hz),
13C-19
117.6, 92.9, 92.7, 91.5, 91.3, 74.8 (d, J C- P=6.0 Hz), 72.2, 70.4 (d,
13
31
127.2, 124.7 (q, J
13
31
C- P=57.4 Hz), 65.7, 61.0, 60.7, 58.6, 58.5, 57.8, 50.7, 32.44,
J
32.40, 29.7, 29.54, 29.51; FABMS (m/z, (%)) 714 (M-BArF, (100));
HRMS (FAB; m/z) calcd for C32H36NPFe193Ir 714.1564, found
714.1502. Anal. Calcd for C64H48BF24FeNPIr: C, 48.75; H, 3.07.
Found: C, 48.79; H, 2.98.
°C); IR (KBr) νmax 3469, 3421, 3048, 2925, 1435 cm-1
;
31P NMR
General Procedure A (Suzuki-Miyaura Couplings). An oven-
dried reaction tube under argon containing a mixture of phenyl-
boronic acid (91 mg, 0.75 mmol), CsF (228 mg, 1.50 mmol), Pd
(OAc)2 (2 mg, 0.01 mmol), and 8a (8 mg, 0.02 mmol) in dioxane
(2.5 mL) was treated with an aryl halide 14a-g (0.50 mmol) and
stirred at room temperature for 5 min before heating to reflux for
22 h. After cooling to room temperature and diluting with Et2O
(7 mL), the mixture was filtered through a pipet containing a plug
of silica gel and eluted with additional Et2O. Evaporation of the
solvent under reduced pressure and recrystallization or column
chromatography gave the purified products 15a-g.
4-Trifluoromethylbiphenyl (15a). According to general proce-
dure A, a mixture of 4-chlorotrifluoromethylbenzene (0.07 mL,
0.50 mmol), phenylboronic acid (91 mg, 0.75 mmol), CsF
(228 mg, 1.50 mmol), Pd(OAc)2 (2 mg, 0.01 mmol), and 8a
(8 mg, 0.02 mmol) in 1,4-dioxane (2.5 mL) was heated to reflux,
cooled, and filtered. Column chromatography (2% EtOAc in
hexane, silica gel) gave 15a (104 mg, 94%) as a colorless crystalline
solid: mp 66-69 °C (95% EtOH) (lit.22 66-68 °C). Spectroscopic
195
31P-
(243 MHz, CDCl3) δ 2.01 (t, J
Pt=1982 Hz); 1H NMR (300
MHz, CDCl3) δ 8.18-8.06 (m, 2H), 7.63-7.40 (m, 6H), 7.39-7.30
(m, 2H), 4.92 (t, 1H, J = 2.6 Hz), 4.53 (s, 1H), 4.29 (t, 1H,
J=1.0 Hz), 3.94 (s, 5H), 3.65 (t, 3H, J=16.6 Hz), 3.24 (t, 3H,
J=15.1 Hz); 1H NMR (600 MHz, acetone-d6) δ 8.24-8.17 (m,
2H), 7.70-7.60 (m, 3H), 7.59-7.53 (m, 2H), 7.53-7.48 (m, 1H),
7.45-7.39 (m, 2H), 5.08 (t, 1H, J=2.3 Hz), 4.94 (s, 1H), 4.62 (t, 1H,
J=1.1 Hz), 4.01 (s, 5H), 3.66 (s, 3H), 3.22 (s, 3H); 13C NMR (150
13
31
13
C- P
31
MHz, CDCl3) δ 134.5 (d, J C- P=11.9 Hz), 132.1 (d, J
2.2 Hz), 131.5 (d, J C- P=10.3 Hz), 131.1 (d, J C- P=68.8 Hz),
=
13
31
13
31
13
31
13
130.9 (d, J C- P=2.7 Hz), 129.1 (d, J C- P=21.6 Hz), 128.9 (d,
31
13
J
31
C- P=73.8 Hz), 128.8 (d, J C- P=11.4 Hz), 128.6 (d, J
13
31
13
31
=
C- P
12.3 Hz), 74.9 (d, J C- P=6.4 Hz), 74.0 (d, J C- P=66.7 Hz), 63.2,
13
31
13
31
13
31
59.7, 59.4 (d, J
= 10.6 Hz), 55.6; FABMS (m/z (%))
C- P
679 (Mþ, 6), 643 (100), 605 (30), 486 (22). Anal. Calcd for
C24H24NPCl2FePt: C, 42.44; H, 3.56. Found: C, 42.67; H, 3.56.
2-Dicyclohexylphosphino-1-dimethylaminoferroceneplatinum
Dichloride (12b). 12b was prepared on a 0.19 mmol scale in a
manner analogous to 12a to give 101 mg (79%) as orange
crystals after recrystallization from CH2Cl2/EtOAc at -20 °C:
mp >225 °C (dec at 210 °C); IR (KBr) νmax 3448, 1460,
(22) Najman, R.; Cho, J.; Coffey, A.; Davies, J.; Bradley, M. Chem.
Commun. 2007, 5031.

Article
Organometallics, Vol. 28, No. 15, 2009 4541
data matched literature reports:23 1H NMR (300 MHz, CDCl3)
δ 7.70 (s, 4H), 7.60 (d, 2H, J=7.2 Hz), 7.50-7.41 (m, 3H).
4-Phenylacetophenone (15b). According to general procedure
A, a mixture of 4-chloroacetophenone (65 μL, 0.50 mmol),
phenylboronic acid (91 mg, 0.75 mmol), CsF (228 mg, 1.50
mmol), Pd(OAc)2 (2 mg, 0.01 mmol), and ligand 8a (8 mg, 0.02
mmol) in 1,4-dioxane (2.5 mL) was heated to reflux, cooled, and
filtered. After evaporation of the solvent, recrystallization from
hexane containing a small amount of EtOAc gave 15b (86 mg,
88%) as colorless crystals. Spectroscopic data matched litera-
ture reports:24 1H NMR (300 MHz, CDCl3) δ 8.05 (d, 2H, J=8.4
Hz), 7.69 (d, 2H, J=8.4 Hz), 7.63 (d, 2H, J=7.2 Hz), 7.50-7.40
(m, 3H), 2.64 (s, 3H); 13C NMR (75.5 MHz, CDCl3) δ 197.7,
145.8, 139.8, 135.8, 128.93, 128.89, 128.2, 127.24, 127.20, 26.6.
4-Cyanobiphenyl (15c). According to general procedure A, a
mixture 4-chlorobenzonitrile (69 mg, 0.50 mmol), phenylboro-
nic acid (91 mg, 0.75 mmol), CsF (228 mg, 1.50 mmol), Pd
(OAc)2 (2 mg, 0.01 mmol), and 8a (8 mg, 0.02 mmol) in 1,4-
dioxane (2.5 mL) was heated to reflux, cooled, and filtered.
Evaporation of the solvent under reduced pressure and column
chromatography of the preadsorbed crude material (5% Et2O in
hexanes, silica gel) gave 15c (83 mg, 92%) as a colorless solid.
Spectroscopic data matched literature reports:25 1H NMR (300
MHz, CDCl3) δ 7.69 (q, 4H, J=6 Hz), 7.61-7.57 (m, 2H), 7.52-
7.40 (m, 3H); 13C NMR (75.5 MHz, CDCl3) δ 145.6, 139.1,
132.5, 129.0, 128.6, 127.6, 127.1, 118.8, 110.8.
(14g, 100 mg, 0.33 mmol), phenylboronic acid (60 mg, 0.50
mmol), CsF (150 mg, 0.99 mmol), Pd(OAc)2 (1.3 mg, 0.007
mmol), and ligand 8a (5.3 mg, 0.013 mmol) in 1,4-dioxane
(2.5 mL) was heated to reflux, cooled, and filtered. After
evaporation of the solvent, recrystallization from Et2O/hexane
gave 15g (86 mg, 88%) as colorless crystals: mp 100-102 °C(Et2O/
hexane); IR (KBr) νmax 3450, 3347, 3050, 3023, 1583 cm-1
;
1H NMR (300 MHz, CDCl3) δ 8.85-8.80 (m, 1H), 8.28 (dd,
1H, J=8.4, 1.5 Hz), 7.66-7.63 (m, 2H), 7.54-7.44 (m, 6H), 7.42-
7.34 (m, 4H), 5.32 (s, 2H); 13C NMR (75.5 MHz, CDCl3)
δ 147.5, 140.2, 139.9, 138.3, 134.2, 130.2, 130.0, 129.2, 129.0,
128.4, 128.2, 127.2, 126.8, 126.1, 121.7, 121.2; EIMS (m/z, (%))
296 (72), 219 (24), 86 (100), 47 (85); HRMS (EI; m/z) calcd for
C21H16N2 296.1314, found 296.1312.
General Procedure B (Buchwald-Hartwig Couplings). An
oven-dried reaction tube under argon containing a mixture of
Pd2(dba)3 CHCl3 (10 mg, 0.01 mmol), 18a (8 mg, 0.02 mmol),
3
and NaOt-Bu (67 mg, 0.70 mmol) in PhMe (2.5 mL) was treated
with an aryl halide (14a,b,d,e,h) (0.50 mmol) and morpholine
(52 μL, 0.60 mmol). The resulting green-brown mixture was
heated at 100 °C for 22 h. After cooling to room temperature, the
reaction mixture was diluted with Et2O (5 mL) and filtered
through a pipet containing a plug of silica gel while eluting with
additional Et2O. Evaporation of the solvent under reduced
pressure and recrystallization or column chromatography of
crude material gave products 16a,b,d,e,h.
2-Nitrobiphenyl (15d). According to general procedure A, a
mixture of o-chloronitrobenzene (79 mg, 0.50 mmol), phenylboro-
nic acid (91 mg, 0.75 mmol), CsF (228 mg, 1.50 mmol), Pd(OAc)2
(2 mg, 0.01 mmol), and 8a (8 mg, 0.02 mmol) in 1,4-dioxane (2.5
mL) was heated to reflux, cooled, and filtered. Evaporation of the
solvent under reduced pressure and column chromatography of
the preadsorbed crude material (1% Et2O in hexane, silica gel)
gave 15d (73 mg, 73%) as a bright yellow oil. Spectroscopic data
matched data literature reports:26 1H NMR (300 MHz, CDCl3)
δ 7.86 (d, 1H, J=8.0 Hz), 7.62 (t, 1H, J=7.5 Hz), 7.51-7.40 (m,
5H), 7.34-7.31 (m, 2H); 13C NMR (75.5 MHz, CDCl3) δ 149.3,
137.4, 136.3, 132.2, 131.9, 128.7, 128.2, 128.1, 127.9, 124.0.
4-Methoxybiphenyl (15e). According to general procedure A,
a mixture of 4-chloroanisole (0.06 mL, 0.50 mmol), phenylboro-
nic acid (91 mg, 0.75 mmol), CsF (228 mg, 1.50 mmol),
Pd(OAc)2 (2 mg, 0.01 mmol), and 8a (8 mg, 0.02 mmol) in 1,4-
dioxane (2.5 mL) was heated to reflux, cooled, and filtered.
Evaporation of the solvent under reduced pressure and column
chromatography of the preadsorbed crude material (0.5-1.0%
isopropanol/hexane, silica gel) gave 15e (64 mg, 70%) as a
colorless solid. Spectroscopic data matched literature reports:1
1H NMR (300 MHz, CDCl3) δ 7.54 (t, 4H, J=6.8 Hz), 7.42 (t,
2H, J=6.8 Hz), 7.32-7.26 (m, 1H), 6.99 (d, 2H, J=8.7 Hz), 3.86
(s, 3H); 13C NMR (75.5 MHz, CDCl3) δ 159.1, 140.8, 133.8,
128.7, 128.1, 126.7, 126.6, 114.2, 55.3.
4-Methylbiphenyl (15f). According to general procedure A, a
mixture of 4-chlorotoluene (59 μL, 0.50 mmol), phenylboronic
acid (91 mg, 0.75 mmol), CsF (228 mg, 1.50 mmol), Pd(OAc)2
(2 mg, 0.01 mmol), and 8a (8 mg, 0.02 mmol) in 1,4-dioxane (2.5
mL) was heated to reflux, cooled, and filtered. Evaporation of the
solvent under reduced pressure and column chromatography of
the preadsorbed crude material (1% Et2O in hexane silica gel)
gave 15f (47 mg, 56%) as a colorless solid. Spectroscopic data
matched literature reports:1 1H NMR (300 MHz, CDCl3)
δ 7.59 (d, 2H, J = 7.8 Hz), 7.51 (d, 2H, J = 7.8 Hz), 7.44 (d, 2H,
J=7.8 Hz), 7.35-7.24 (m, 3H), 2.41 (s, 3H);13CNMR (75.5MHz,
CDCl3) δ 141.1, 138.3, 137.0, 129.5, 128.7, 127.0, 126.9, 21.1.
5,7-Diphenyl-8-aminoquinoline (15g). According to general
procedure A, a mixture of 5,7-dibromo-8-aminoquinoline
N-(4-Trifluoromethylphenyl)morpholine (16a). According to
general procedure B, a mixture of 4-chlorotrifluoromethylbenzene
(67 μL, 0.50 mmol), morpholine (52 μL, 0.60 mmol), NaOt-Bu
(67 mg, 0.70 mmol), Pd2(dba)3 CHCl3 (10 mg, 0.01 mmol), and 8a
3
(8 mg, 0.02 mmol) in PhMe (2.5 mL) was heated, cooled, and
filtered. Evaporation of the solvent under reduced pressure and
column chromatography of the preadsorbed crude material (20%
Et2O in hexane, silica gel) gave 16a (89 mg, 77%) as off-white
crystals. Spectroscopic data matched literature reports:23 1H
NMR (300 MHz, CDCl3) δ 7.50 (d, 2H, J = 8.7 Hz), 6.92 (d,
2H, J=8.7 Hz), 3.87 (t, 4H, J=4.8 Hz), 3.24 (t, 4H, J=5.1 Hz); 13
C
13
31
NMR (75.5 MHz, CDCl3) δ 153.3, 126.4 (q, J C- P=3 Hz), 124.6
13
31
13
31
(q, J C- P=271 Hz), 120.9 (q, J C- P=33 Hz) 114.3, 66.6, 48.1.
N-(4-Acetylphenyl)morpholine (16b). According to general
procedure B, a mixture of 4-chloroacetophenone (65 μL, 0.50
mmol), morpholine (52 μL, 0.60 mmol), NaOt-Bu (67 mg, 0.70
mmol), Pd2(dba)3 CHCl3 (10 mg, 0.01 mmol), and 8a (8 mg,
3
0.02 mmol) in PhMe (2.5 mL) was heated, cooled, and filtered.
Evaporation of the solvent under reduced pressure and column
chromatography of the preadsorbed crude material (83:2:15 to
78:2:20 hexane/Et3N/EtOAc, silica gel) gave 16b (76 mg, 74%)
as a pale yellow solid. Spectroscopic data matched literature
reports:1 1H NMR (300 MHz, CDCl3) δ 7.90 (d, 2H, J=9.0 Hz),
6.87 (d, 2H, J=9.0 Hz), 3.86 (t, 4H, J=4.8 Hz), 3.31 (t, 4H, J=
5.1 Hz), 2.53 (s, 3H); 13C NMR (75.5 MHz, CDCl3) δ 196.4,
154.2, 130.3, 128.1, 113.2, 66.5, 47.5, 26.1.
N-(2-Nitrophenyl)morpholine (16d). According to general
procedure B, a mixture of 2-nitrochlorobenzene (79 mg, 0.50
mmol), morpholine (52 μL, 0.60 mmol), NaOt-Bu (67 mg, 0.70
mmol), Pd2(dba)3 CHCl3 (10 mg, 0.01 mmol), and 8b (0.4 mL of
3
a 0.05 M solution in PhMe) in PhMe (2.5 mL) was heated,
cooled, and filtered. Evaporation of the solvent under reduced
pressure and column chromatography of the preadsorbed crude
material (40% Et2O in hexane, silica gel) gave 16d (45 mg, 43%)
as a yellow oil. Spectroscopic data matched literature reports:27
1H NMR (300 MHz, CDCl3) δ 7.79 (d, 1H, J = 8.1 Hz), 7.52-
7.47 (m, 1H), 7.15 (d, 1H, J = 8.3 Hz), 7.10-7.06 (m, 1H), 3.85-
3.83 (m, 4H), 3.07-3.04 (m, 4H); 13C NMR (75.5 MHz, CDCl3)
δ 145.8, 143.7, 133.5, 125.9, 122.3, 120.9, 66.8, 52.1.
N-(4-Methoxyphenyl)morpholine (16e). According to general
procedure B, a mixture of 4-bromoanisole (63 μL, 0.50 mmol),
(23) Ackermann, L.; Bom, R. Angew. Chem., Int. Ed. 2005, 44, 2444.
(24) Mino, T.; Shirae, Y.; Sakamoto, M.; Fujita, T. J. Org. Chem.
2005, 70, 2191.
(25) Su, W.; Urgaonkar, S.; Verkade, J. Org. Lett. 2004, 6, 1421.
(26) Rasala, D.; Gawinecki, R. Magn. Reson. Chem. 1992, 30, 740.
(27) Shi, L.; Wang, M.; Fan, C.; Zhang, F.; Tu, Y. Org. Lett. 2003, 5,
3515.

4542 Organometallics, Vol. 28, No. 15, 2009
Metallinos et al.
morpholine (52 μL, 0.60 mmol), NaOt-Bu (67 mg, 0.70 mmol),
Pd2(dba)3 CHCl3 (10 mg, 0.01 mmol), and 8a (8 mg, 0.02 mmol)
(sextet, 1H, J=7.2 Hz), 2.67-2.51 (m, 2H), 1.32 (d, 3H, J=6.9
Hz), 1.19 (t, 3H, J=6.9 Hz); 13C NMR (75.5 MHz, CDCl3)
δ 172.5, 145.9, 128.6, 126.9, 126.5, 60.3, 43.1, 36.6, 21.9, 14.3.
Ethyl 3-(4-Methoxyphenyl)butanoate (18e). According to gen-
eral procedure C, a solution of ethyl 3-(4-methoxyphenyl)but-
2-enoate (60 mg, 0.27 mmol) and 13 (8.7 mg, 0.0055 mmol,
2.0 mol %) in CH2Cl2 (3 mL) was pressurized with H2 to 62 bar
and stirred for 72 h. Filtration of the reaction mixture and
evaporation of the solvent gave 18e as a clear oil (59 mg, 96%):
1H NMR32 (300 MHz, CDCl3) δ 7.14 (d, 2H, J=8.7 Hz), 6.84 (d,
2H J=6.9 Hz), 4.07 (q, 2H, J=7.2 Hz), 3.78 (s, 3H), 3.23 (sextet,
1H, J=7.2 Hz), 2.61-2.47 (m, 2H), 1.28 (d, 3H, J = 6.9 Hz), 1.19
(t, 3H, J=7.2 Hz); 13C NMR (75.5 MHz, CDCl3) δ 172.6, 158.2,
138.0, 127.8, 113.9, 60.3, 55.4, 43.4, 35.9, 22.1, 14.3.
3
in PhMe (2.5 mL) was heated, cooled, and filtered. Evaporation
of the solvent under reduced pressure and column chromatog-
raphy of the preadsorbed crude material (2:50:48 Et3N/Et2O/
hexane, silica gel) gave 16e (64 mg, 67%) as an off-white solid.
Spectroscopic data matched literature reports:28 1H NMR (300
MHz, CDCl3) δ 6.92-6.84 (m, 4H), 3.86 (t, 4H, J=4.8 Hz), 3.77
(s, 3H), 3.06 (t, 4H, J=4.8 Hz); 13C NMR (75.5 MHz, CDCl3)
δ 153.9, 145.5, 117.7, 114.4, 66.9, 55.5, 50.7.
N-Phenylmorpholine (16h). According to general procedure B,
a mixture of bromobenzene (53 μL, 0.50 mmol), morpholine
(52 μL, 0.60 mmol), NaOt-Bu (67 mg, 0.70 mmol), Pd2(dba)3
3
CHCl3 (10 mg, 0.01 mmol), and 8a (8 mg, 0.02 mmol) in PhMe
(2.5 mL), was heated, cooled, and filtered. Column chromatogra-
phy (6:1:93 Et2O/Et3N/hexane, silica gel) gave 16h (67 mg, 82%) as
a colorless solid. Spectroscopic data matched literature reports:27
1H NMR (600 MHz, CDCl3) δ 7.32 (t, 2H, J=4.2 Hz), 6.97-6.91
(m, 3H), 3.90 (t, 4H, J=2.4 Hz), 3.19 (t, 4H, J=2.4 Hz); 13C NMR
(150.9 MHz, CDCl3) δ 151.3, 129.2, 120.1, 115.7, 67.0, 49.4.
General Procedure C (Hydrogenation). A solution of substrate
(∼0.2-0.3 mmol) and iridium catalyst 13 (2 mol %) in CH2Cl2
(3 mL) in a vial under argon was sealed in an autoclave. The
autoclave was evacuated and backfilled with H2 three times,
pressurized to 62 bar, and stirred at room temperature for the
indicated time. After the pressure was released, the reaction
mixture was passed through a plug of silica gel, eluting with
Et2O to remove catalyst residue. Products obtained in this
manner were sufficiently pure, as determined by melting point
and/or spectroscopic analysis.
1,3-Diphenylpropan-1-one (18f). According to general proce-
dure C, a solution of chalcone (17f, 50 mg, 0.24 mmol) and 13
(7.4 mg, 0.0047 mmol, 2.0 mol %) in CH2Cl2 (3 mL) was
pressurized with H2 to 62 bar and stirred for 96 h. Filtration
of the reaction mixture and evaporation of the solvent gave 18f
as a colorless solid (50 mg, 99%): mp 69-70 °C (lit.33 70-72 °C);
1H NMR33 (300 MHz, CDCl3) δ 7.98 (d, 2H, J=7.2 Hz), 7.6-
7.2 (m, 8H), 3.33 (t, 2H, J=7.8 Hz), 3.10 (t, 2H, J=7.2 Hz); 13
C
NMR32 (75.5 MHz, CDCl3) δ 199.3, 141.4, 136.9, 133.2, 128.7,
128.6, 128.5, 128.1, 126.2, 40.5, 30.2.
N-(1-Phenylethyl)aniline (18g). According to general proce-
dure C, a solution of N-(1-phenylethylidene)aniline (50 mg, 0.26
mmol) and 13 (7.8 mg, 0.0050 mmol, 1.9 mol %) in CH2Cl2 (3
mL) was pressurized with H2 to 62 bar and stirred for 72 h.
Filtration of the reaction mixture and evaporation of the solvent
1
gave 18g as a clear oil (41 mg, 81%): H NMR34 (300 MHz,
1,2-Diphenylethane (18a). According to general procedure C,
a solution of trans-stilbene (50 mg, 0.28 mmol) and 13 (8.8 mg,
0.0056 mmol, 2.0 mol %) in CH2Cl2 (3 mL) was pressurized with
H2 to 62 bar and stirred for 48 h. Filtration of the reaction
mixture and evaporation of the solvent gave 18a (50 mg, 97%):
mp 48-50 °C (lit.29 47-49 °C); 1H NMR (300 MHz, CDCl3) δ
7.39-7.25 (m, 10H), 3.01 (s, 4H); 13C NMR (75.5 MHz, CDCl3)
δ 141.9, 128.6, 128.5, 126.0, 38.1.
1,2-Diphenylpropane (18b). According to general procedure
C, a solution of methyl stilbene (40 mg, 0.21 mmol) and 13 (6.4
mg, 0.0041 mmol, 2.0 mol %) in CH2Cl2 (3 mL) was pressurized
with H2 to 62 bar and stirred for 24 h. Filtration of the reaction
mixture and evaporation of the solvent gave 18b as a clear oil (35
mg, 86%): 1H NMR30 (300 MHz, CDCl3) δ 7.35-7.12 (m, 10H),
3.10-2.98 (m, 2H), 2.88-2.79 (m, 1H), 1.30 (d, 3H, J=6.9 Hz);
13C NMR (75.5 MHz, CDCl3) δ 147.1, 140.9, 129.3, 128.4,
128.2, 127.2, 126.1, 126.0, 45.1, 42.0, 21.3.
CDCl3) δ 7.50-7.35 (m, 4H), 7.30-7.25 (m, 1H), 7.15 (t, 2H, J=
7.5 Hz), 6.70 (t, 1H, J=7.5 Hz), 6.59 (d, 2H, J=7.5 Hz), 4.56
(quin, 1H, J=6.6 Hz), 4.08 (bs, 1H), 1.56 (d, 3H, J=6.6 Hz); 13
C
NMR (75.5 MHz, CDCl3) δ 147.4, 145.4, 129.3, 128.8, 127.0,
126.0, 117.4, 113.4, 53.6, 25.2.
N-Benzyl-1-phenylethanamine (18h). According to general
procedure C, a solution of 1-phenyl-N-(1-phenylethylidene)
methanamine (50 mg, 0.24 mmol) and 13 (7.5 mg, 0.0048 mmol,
2.0 mol %) in CH2Cl2 (3 mL) was pressurized with H2 to 62 bar
and stirred for 72 h. Filtration of the reaction mixture and
evaporation of the solvent gave 18h as a clear oil (45 mg, 88%):
1H NMR35 (300 MHz, CDCl3) δ 7.35-7.27 (m, 10H), 3.85
(q, 1H, J=6.6 Hz), 3.66 (ABq, 2H, J=13.2 Hz), 1.59 (bs, 1H),
1.39 (d, 3H, J=6.6 Hz); 13C NMR (75.5 MHz, CDCl3) δ 145.7,
140.8, 128.6, 128.5, 128.3, 127.0, 126.95, 126.8, 57.6, 51.8, 24.7.
3,7-Dimethyloctan-1-ol (18i). According to general procedure
C, a solution of geraniol (52 μL, 0.29 mmol) and 13 (9.0 mg,
0.0057 mmol, 2.0 mol %) in CH2Cl2 (3 mL) was pressurized with
H2 to 62 bar and stirred for 24 h. Filtration of the reaction
mixture and evaporation of the solvent gave 18i as a clear liquid
Methyl 3-Phenylpropanoate (18c). According to general pro-
cedure C, a solution of methyl trans-cinnamate (49 mg, 0.30
mmol) and 13 (9.8 mg, 0.0062 mmol, 2.0 mol %) in CH2Cl2
(3 mL) was pressurized with H2 to 62 bar and stirred for 48 h.
Filtration of the reaction mixture and evaporation of the solvent
1
(47 mg, 98%): H NMR36 (300 MHz, CDCl3) δ 3.68 (m, 2H),
1.61-1.17 (m, 10 H), 0.90 (s, 9H); 13C NMR (75.5 MHz, CDCl3)
δ 61.4, 30.1, 39.4, 37.5, 29.7, 28.1, 24.8, 22.8, 22.7, 19.8.
1
gave 18c as a clear oil (48 mg, 95%): H NMR29 (300 MHz,
CDCl3) δ 7.33-7.19 (m, 5H), 3.68 (s, 3H), 2.97 (t, 2H, J=8.1
Hz), 2.65 (t, 2H, J=7.8 Hz); 13C NMR (75.5 MHz, CDCl3)
δ 173.4, 140.6, 128.6, 128.4, 126.4, 51.7, 35.8, 31.0.
Pyrrolidine-2,5-dione (18j). According to general procedure C,
a solution of maleimide (32 mg, 0.33 mmol) and 13 (10.4 mg,
0.0066 mmol, 2.0 mol %) in CH2Cl2 (3 mL) was pressurized with
H2 to 62 bar and stirred for 96 h. Filtration of the reaction mixture
and evaporation of the solvent gave 18j as a colorless solid (27 mg,
82%): mp 125-127 °C (lit.37 125-127 °C); 1H NMR38 (300 MHz,
Ethyl 3-Phenylbutanoate (18d). According to general proce-
dure C, a solution of ethyl 3-phenylbut-2-enoate (54 mg, 0.28
mmol) and 13 (9.0 mg, 0.0057 mmol, 2.0 mol %) in CH2Cl2
(3 mL) was pressurized with H2 to 62 bar and stirred for 48 h.
Filtration of the reaction mixture and evaporation of the solvent
1
gave 18d as a clear oil (52 mg, 94%): H NMR31 (300 MHz,
(32) Kamigata, N.; Satoh, A.; Yoshida, M. Phosphorus, Sulfur,
Silicon Relat. Elem. 1989, 46, 121.
(33) Fox, D. J.; Pedersen, D. S.; Warren, S. Org. Biomol. Chem. 2006,
4, 3102.
(34) Storer, R. I.; Carrera, D. E.; Ni, Y.; MacMillan, D. W. C. J. Am.
CDCl3) δ 7.34-7.18 (m, 5H), 4.10 (q, 2H, J = 7.2 Hz), 3.28
(28) Urgaonkar, S.; Verkade, J. J. Org. Chem. 2004, 69, 9135.
(29) Black, P. J.; Edwards, M. G.; Williams, J. M. J. Eur. J. Org.
Chem. 2006, 19, 4367.
(30) Ruano, J. L. G.; Aranda, M. T.; Puente, M. Tetrahedron 2006,
61, 10099.
(31) Llamas, T.; Arrayas, R. G.; Carretero, J. C. Angew. Chem., Int.
Chem. Soc. 2006, 128, 84.
(35) Samec, J. S. M.; Backvall, J. E. Chem.;Eur. J. 2002, 8, 2955.
(36) Buszek, K. R.; Brown, N. J. Org. Chem. 2007, 72, 3125.
(37) Taherpour, A. A.; Mansuri, H. R. Turk. J. Chem. 2005, 29, 317.
(38) Spectral Database for Organic Compounds (SDBS) (http://
riodb01.ibase.aist.go.jp/sdbs/cgi-bin/direct_frame_top.cgi).
Ed. 2007, 46, 3329.

Article
Organometallics, Vol. 28, No. 15, 2009 4543
acetone-d6) δ 2.68 (s, 4H), 9.88 (bs, 1H); 13C NMR38 (75.5 MHz,
acetone-d6) δ 178.9, 30.2.
(quin, 1H, J=6.6 Hz), 0.87 (dd, 6H, J=6.9 Hz, 0.9 Hz); 13C
NMR (75.5 MHz, CDCl3) δ 200.6, 145.2, 135.2, 42.0, 41.9, 31.9,
29.8, 19.5, 19.4 15.6.
Cyclohexanone (18k). According to general procedure C, a
solution of cyclohexenone (30 μL, 0.31 mmol) and 13 (9.8 mg,
0.0062 mmol, 2.0 mol %) in CH2Cl2 (3 mL) was pressurized with
H2 to 62 bar and stirred for 48 h. Filtration of the reaction
mixture and evaporation of the solvent gave 18k as a clear liquid
(26 mg, 84%): 1H NMR38 (300 MHz, CDCl3) δ 2.31 (t, 4H, J=
6.9 Hz), 1.85-1.81 (m, 4H), 1.70-1.69 (m, H); 13C NMR38 (75.5
MHz, CDCl3) δ 212.2, 40.1, 27.1, 25.1.
2,3-Dihydronaphthalene-1,4-dione (18l). According to general
procedure C, a solution of naphthoquinone (50 mg, 0.31 mmol)
and 13 (10.0 mg, 0.0063 mmol, 2.0 mol %) in CH2Cl2 (3 mL) was
pressurized with H2 to 62 bar and stirred for 72h. Filtration ofthe
reaction mixture and evaporation of the solvent gave the crude
product, which was purified by column chromatography (30%
EtOAc in hexane, silica gel) to give 18l (45 mg, 89%) as a 2:1
mixture of 2,3-dihydronaphthalene-1,4-dione and 1,4-dihydro-
naphthalene-1,4-diol: 1H NMR (300 MHz, acetone-d6, 2,3-dihy-
dronaphthalene-1,4-dione39) δ 8.00-7.97 (m, 2H), 7.83-7.81 (m,
2H), 3.11 (s, 4H); 1,4-(dihydronaphthalene-1,4-diol40) δ 8.32
(bs, 2H), 8.18-8.15 (m, 2H), 7.47-7.43 (m, 2H), 6.73 (s, 2H).
Chroman-4-one (18m). Prepared according to a modification
of general procedure C. A solution of chromone (45 mg, 0.31
2-Benzyl-3-methyl-2-aza-spiro[4.5]decane (20). A solution of
aminoalkene 19 (135 mg, 0.55 mmol) and 13 (22 mg, 2.5 mol %)
in dioxane (2 mL) under argon was heated to reflux for 22 h.
After cooling to room temperature, the solvent was removed on
a rotary evaporator. The residue was taken up in Et2O and
filtered through a pipet of silica gel and concentrated again in
vacuo. The crude product mixture was dissolved in THF (2 mL),
treated with Ac2O (63 μL, 1.2 equiv), Et3N (0.23 mL, 3.0 equiv)
and DMAP (3 mg, 0.05 equiv), and heated at 45 °C for 16 h to
acylate any remaining secondary amines. The reaction mixture
was then diluted with Et2O and extracted with 1 M aqueous HCl
(3 ꢀ 5 mL), and the combined acidic extracts were made alkaline
(pH 12) by addition of 6 M aqueous NaOH. The aqueous phase
was back-extracted with Et2O (3 ꢀ 5 mL), washed with brine,
dried over anhydrous Na2SO4, filtered, and concentrated in
vacuo to give 20 (87 mg, 64%) as a pale yellow oil. Spectroscopic
data were in agreement with literature reports:43 1H NMR (300
MHz, CDCl3) δ 7.38-7.22 (m, 5H), 4.04 (d, 1H, J=13.2 Hz),
3.12 (d, 1H, J=13.2 Hz), 2.81 (d, 1H, J= 9.3 Hz), 2.58-2.46 (m,
1H), 1.90 (d, 1H, J=9.3 Hz), 1.78 (ABq, 1H, J=12.6, 6.9 Hz),
1.50-1.25 (m, 11H), 1.17 (d, 3H, J=6.0 Hz).
€
mmol), Hunig’s base (540 μL), and 13 (9.8 mg, 0.0062 mmol, 2.0
mol %) in PhMe (3 mL) was pressurized with H2 to 100 bar and
stirred for 48 h. Filtration of the reaction mixture and evapora-
tion of the solvent gave the crude product, which was purified by
column chromatography (30% EtOAc in hexane, silica gel) to
give 18m (30 mg, 66%) as a colorless oil: 1H NMR41 (300 MHz,
CDCl3) δ 7.90 (dd, 1H, J=7.8, 1.5 Hz), 7.50-7.45 (m, 1H),
7.05-6.96 (m, 2H), 4.54 (t, 2H, J=6.6 Hz), 2.82 (t, 2H, J=6.3
Hz); 13C NMR (75.5 MHz, CDCl3) δ 192.0, 162.0, 136.1, 127.3,
121.5, 118.0, 67.1, 37.9.
Acknowledgment. We thank NSERC for support of
our research program and T. Jones and R. Simionescu
(Brock University) for assistance with spectroscopic data
collection. J.Z. thanks the Province of Ontario for two
OGSST grants (2007 and 2008) and an OGS grant (2009).
L.D. thanks Brock University for support through the
Experience Works program, and NSERC for an Under-
graduate Student Research Award (USRA) grant (2009).
Prof. Martin Lemaire (Brock University) is thanked for
providing a sample of 14g. We also thank Drs. Hilary A.
Jenkins and James F. Britten (McMaster University) for
X-ray crystallography of 11a.
5-Isopropyl-2-methylcyclohex-2-enone (18n). According to
general procedure C, a solution of carvone (45 μL, 0.29 mmol)
and 13 (8.0 mg, 0.0051 mmol, 1.8 mol %) in CH2Cl2 (3 mL) was
pressurized with H2 to 62 bar and stirred for 48 h. Filtration of
the reaction mixture and evaporation of the solvent gave 18n as a
1
colorless oil (43 mg, 96%): H NMR42 (300 MHz, CDCl3) δ
Supporting Information Available: Crystallographic informa-
tion files (CIF) for 11a, 12a, and 13. This material is available
free of charge via the Internet at http://pubs.acs.org. CCDC
732234, 732235, and 732236 also contain crystallographic data
for compounds 13, 11a, and 12a, respectively. This material can
be obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
6.72-6.69 (m, 1H), 2.53-2.47 (m, 1H), 2.37-2.27 (m, 1H),
2.13-1.99 (m, 2H), 1.85-1.78 (m, 1H), 1.73-1.72 (m, 3H), 1.54
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