Phenyl backbone-derived P,O- and P,N-ligands for palladium/ligand-catalyzed aminations of aryl bromides, iodides, and chlorides. syntheses and structures of (P,O)n-palladium(II)aryl(Br) complexes

Article abstract of DOI:10.1021/om9900162

The phenyl backbone-derived P,O- and P,N-compounds 1-10 were investigated for their utility as ligands in palladium/ligand-catalyzed aryl animations. The P,O-ligands 2-(2′-diphenylphosphinophenyl)-2-methyl-1,3-dioxolane (1) and 2-(2′-dicyclohexylphosphinophenyl)-2-methyl-1,3-dioxolane (6) in combination with Pd(dba)₂ afford active catalysts for general aminations of aryl bromides, iodides, and chlorides. The Pd/ligand 6 catalyst, in particular, is efficient for general aminations of aryl chlorides. But the structurally related ligand 2-(2′-diphenylphosphinophenyl)-1,3-dioxolane (2) and other P,O- or P,N-ligands were less effective. The reactions of Pd(dba)₂ with excess 4-^tBu-C₆H₄Br and excess ligand (1, 6, 2) or the ligand displacement reactions of {Pd[P(o-toluyl)₃](4-^tBu-C₆H ₄)(μ-Br)}₂ with ligands 1, 6, and 2 afford the potential catalytic intermediates of Pd/L-catalyzed (L = 1, 6, 2) aryl aminations, viz., LPd(4-^tBu-C₆H₄)(Br) (11, L = 1; 12, L = 6) and L₂Pd(4-^tBu-C₆H₄)(Br) (13, L = 2), respectively. The X-ray crystallographic studies establish that ligands 1 and 6 function as P,O-chelating ligands in complexes 11 and 12, respectively, while ligand 2 functions as a monodentate P-ligand in complex 13. The NMR spectroscopic studies indicate that complexes 11-13 retain their solid-state structures in solution. The higher efficiency of ligands 1 and 6 in comparison with ligand 2 and other P,O- or P,N-ligands in Pd/L-catalyzed aryl aminations most likely results from the formation of the P,O-chelating Pd/L complexes, which appear to be most suitable for aryl aminations involving this class of ligands.

Full text of DOI:10.1021/om9900162

1840
Organometallics 1999, 18, 1840-1853
P h en yl Ba ck bon e-Der ived P ,O- a n d P ,N-Liga n d s for
P a lla d iu m /Liga n d -Ca ta lyzed Am in a tion s of Ar yl
Br om id es, Iod id es, a n d Ch lor id es. Syn th eses a n d
Str u ctu r es of (P ,O)n -P a lla d iu m (II)Ar yl(Br ) Com p lexes
Xiaohong Bei, Tetsuo Uno, J eff Norris, Howard W. Turner,
W. Henry Weinberg, and Anil S. Guram*
Symyx Technologies, 3100 Central Expressway, Santa Clara, California 95051
J effrey L. Petersen
Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506
Received J anuary 13, 1999
The phenyl backbone-derived P,O- and P,N-compounds 1-10 were investigated for their
utility as ligands in palladium/ligand-catalyzed aryl aminations. The P,O-ligands 2-(2′-
diphenylphosphinophenyl)-2-methyl-1,3-dioxolane (1) and 2-(2′-dicyclohexylphosphinophen-
yl)-2-methyl-1,3-dioxolane (6) in combination with Pd(dba)2 afford active catalysts for general
aminations of aryl bromides, iodides, and chlorides. The Pd/ligand 6 catalyst, in particular,
is efficient for general aminations of aryl chlorides. But the structurally related ligand 2-(2′-
diphenylphosphinophenyl)-1,3-dioxolane (2) and other P,O- or P,N-ligands were less effective.
The reactions of Pd(dba)2 with excess 4-tBu-C6H4Br and excess ligand (1, 6, 2) or the ligand
displacement reactions of {Pd[P(o-toluyl)3](4-tBu-C6H4)(µ-Br)}2 with ligands 1, 6, and 2 afford
the potential catalytic intermediates of Pd/L-catalyzed (L ) 1, 6, 2) aryl aminations, viz.,
LPd(4-tBu-C6H4)(Br) (11, L ) 1; 12, L ) 6) and L2Pd(4-tBu-C6H4)(Br) (13, L ) 2), respectively.
The X-ray crystallographic studies establish that ligands 1 and 6 function as P,O-chelating
ligands in complexes 11 and 12, respectively, while ligand 2 functions as a monodentate
P-ligand in complex 13. The NMR spectroscopic studies indicate that complexes 11-13 retain
their solid-state structures in solution. The higher efficiency of ligands 1 and 6 in comparison
with ligand 2 and other P,O- or P,N-ligands in Pd/L-catalyzed aryl aminations most likely
results from the formation of the P,O-chelating Pd/L complexes, which appear to be most
suitable for aryl aminations involving this class of ligands.
In tr od u ction
assisting palladium- and nickel-catalyzed aminations of
aryl bromides, iodides, and triflates with primary alky-
lamines and secondary cyclic amines, but proved to be
unsuitable in related aminations involving secondary
acyclic alkylamines and diarylamines. Similarly, bis[2-
(diphenylphosphino)phenyl]ether (DPEphos) was found
to exhibit improved efficiency in specifically assisting
palladium-catalyzed amination of aryl bromides with
anilines.2h The ferrocenyl backbone-derived mono-phos-
The palladium-catalyzed aminations1 of aryl bro-
mides,2 iodides,3 triflates,4 chlorides,5 and tosylates5b,6
with primary and secondary amines provide a general
and efficient route to a wide variety of industrially sig-
nificant arylamines7 and represent a truly remarkable
development in the important field of metal-catalyzed
C-N bond formation.8 After the original discovery of
the utility of the tris(o-toluyl)phosphine ligand in as-
sisting palladium-catalyzed aminations of aryl ha-
lides,1a,b,d,2a,c a variety of ligands exhibiting improved,
but substrate-specific, efficiency were discovered.2b,d-f,4,5
The bis-phosphines 2,2′-bis(diphenylphosphino)-1,1′-bi-
naphthyl (BINAP) and diphenylphosphinoferrocene
(DPPF) were found to exhibit improved ability in
(2) For leading references to palladium-catalyzed aminations of aryl
bromides, see: (a) Guram, A. S.; Rennels, R. A.; Buchwald, S. L. Angew.
Chem., Int. Ed. Engl. 1995, 34, 1348-1350. (b) Wolfe, J . P.; Wagaw,
S.; Buchwald, S. L. J . Am. Chem. Soc. 1996, 118, 7215-7216. (c) Louie,
J .; Hartwig, J . F. Tetrahedron Lett. 1995, 36, 3609-3612. (d) Driver,
M. S.; Hartwig, J . F. J . Am. Chem. Soc. 1996, 118, 7217-7218. (e)
Marcoux, J .-F.; Wagaw, S.; Buchwald, S. L. J . Org. Chem. 1997, 62,
1568-1569. (f) Nishiyama, M.; Yamamoto, T.; Koie, Y. Tetrahedron
Lett. 1998, 39, 617-620. (g) Wolfe, J . P.; Buchwald, S. L. Tetrahedron
Lett. 1997, 38, 6359-6362. (h) Sadighi, J . P.; Harris, M. C.; Buchwald,
S. L. Tetrahedron Lett. 1998, 39, 5327-5330. (i) Rossen, K.; Pye, P.
J .; Maliakal, A.; Volante, R. P. J . Org. Chem. 1997, 62, 6462-6463.
For palladium-catalyzed aminations of solid-supported aryl bromides,
see: (j) Willoughby, C. A.; Chapman, K. T. Tetrahedron Lett. 1996,
37, 7181-7184. (k) Ward, Y. D.; Farina, V. Tetrahedron Lett. 1996,
37, 6993-6996. For palladium-catalyzed aryl aminations in water-
containing solvent systems (biphase catalysis), see: (l) Wullner, G.;
J ansch, H.; Kannenberg, S.; Schubert, F.; Boche, G. Chem. Commun.
1998, 1509. For latest developments in Pd/L-catalyzed aryl aminations
of aryl bromides, see also ref 5.
(1) Palladium-catalyzed aminations of aryl halides with aminostan-
nanes were first investigated and reported by Kosugi et al.: (a) Kosugi,
M.; Kameyama, M, Migita, T. Chem. Lett. 1983, 927-928. (b) Kosugi,
M.; Kameyama, M.; Sano, H.; Migita, T. Nippon Kagaku Kaishi 1985,
3, 547-551. The aminostannane-based methodology was later signifi-
cantly generalized by the employment of a transamination-Pd-catalysis
protocol by Buchwald et al. (c) Guram, A. S.; Buchwald, S. L. J . Am.
Chem. Soc. 1994, 116, 7901-7902. The tin-free metal-catalyzed aryl
aminations were subsequently developed; see refs 2-5 and: (d)
Buchwald, S. L.; Guram, A. S. US Patent 5,576,460, 1996.
10.1021/om9900162 CCC: $18.00 © 1999 American Chemical Society
Publication on Web 04/21/1999

(P,O)n-Palladium(II)Aryl(Br) Complexes
Organometallics, Vol. 18, No. 10, 1999 1841
Sch em e 1
phines, 1-[2-(diphenylphosphino)ferrocenyl]ethyl dimeth-
ylamine (PPFA) and 1-[2-(diphenylphosphino)ferroce-
nyl]ethyl methyl ether (PPFOMe), containing a pendant
nitrogen and oxygen functionality, respectively, were
later identified as ligands of choice for palladium-cata-
lyzed aminations of aryl bromides with acyclic secondary
alkylamines.2e The palladium-catalyzed aryl aminations
remained generally9 limited to aryl bromides, idodides,
and triflates until it was discovered that simple mono-
phosphines, tricylcohexylphosphine and tri-tert-butyl-
phosphine, exhibit promising ability in assisting pal-
ladium-catalyzed aminations of aryl halides including
aryl chlorides,2f,5c,g although only cyclic secondary amines
and biarylamines were demonstrated to be practically
suitable substrates. Following these reports, it was more
recently demonstrated that di-tert-butylphosphine and
dicyclohexylphosphine containing bis-phosphines, 1,1′-
bis(di-tert-butylphosphino)ferrocene (DBtPF), 1-[2-(di-
phenylphosphino)ferrocenyl]ethyldi-tert-butylphosphine
(PPFBtP), and 1-[2-(dicyclohexylphosphino)ferrocenyl]eth-
yldicyclohexyl phosphine (DCPFDCP), and the dicylo-
hexylphosphine containing mono-phosphine, 2-(dicylco-
hexylphosphino)-2′-(dimethylamino)-1,1′-binaphthyl (DC-
PA-BINAP), exhibit improved ability in assisting pal-
ladium-catalyzed aminations of aryl chlorides with a
wider variety of arylamines (Scheme 1).5a,b The DBtPF
and PPFBtP ligands were also found to assist similar
aminations of aryl tosylates.5b While several ligands
exhibiting improved abilities in assisting the palladium-
and nickel-catalyzed aryl aminations are now available,
a general solution to the metal-catalyzed aryl amina-
tions of all substrates has not been completely achieved.
Particularly, prior to this work,10 the aminations of aryl
chlorides with secondary acylic alkylamines were not
generally achieved, and similar aminations of aryl bro-
mides and general aryl aminations of aryl chlorides
were limited to rather exotic, expensive, or relatively
inaccessible ferrocenyl and binaphthyl backbone-derived
ligands. It is anticipated that further commercial de-
velopment of this important synthetic methodology will
necessitate the discovery of simple, inexpensive, and
readily accessible ligands which exhibit similar, if not
better, ability in assisting metal-catalyzed aryl amina-
tions compared to the present state of the art.
Thus, as part of our ongoing efforts to identify, de-
velop, and utilize high-throughput methods for the rapid
discovery of useful materials,11 we investigated the util-
ity of a variety of simple and readily accessible ligands
in assisting metal-catalyzed aryl aminations. This in-
vestigation led to the identification of a class of 1,2-
phenyl backbone-substituted phosphines containing a
pendant heteroatom functionality as promising lead
ligand structures.12 We then initiated a more detailed
study of these and several related ligand structures,
their palladium complexes, and their utility in assisting
palladium-catalyzed aryl aminations. Herein, we de-
scribe the results of this study and demonstrate that
these simple and readily accessible ligands efficiently
assist the palladium-catalyzed aryl aminations of a wide
variety of substrates, including secondary acyclic alkyl-
amines and the commercially significant aryl chlorides.
We also demonstrate that slight variations in ligand
structures dramatically influence the structures of the
palladium-ligand complexes and the catalytic effi-
ciency.
(3) Leading references for palladium-catalyzed aminations of aryl
iodides, see refs 2b,d and: (a) Wolfe, J . P.; Buchwald, S. L. J . Org.
Chem. 1996, 61, 1133-1135. For latest developments, see ref 5.
(4) For leading references for palladium-catalyzed aminations of aryl
triflates, see: (a) Wolfe, J . P.; Buchwald, S. L. J . Org. Chem. 1997,
62, 1264-1267. (b) Louie, J .; Driver, M. S.; Hamann, B. C.; Hartwig,
J . F. J . Org. Chem. 1997, 62, 1268-1273. (c) Ahman, J .; Buchwald, S.
L. Tetrahedron Lett. 1997, 38, 6363-6366.
(5) For leading references for palladium-catalyzed aminations of aryl
chlorides, see: (a) Old, D. W.; Wolfe, J . P.; Buchwald, S. L. J . Am.
Chem. Soc. 1998, 120, 9722-9723. (b) Hamann, B. C.; Hartwig, J . F.
J . Am. Chem. Soc. 1998, 120, 7369-7370. (c) Reddy, N. P.; Tanaka,
M. Tetrahedron Lett. 1997, 38, 4807-4810. (d) Beller, M.; Reirmeier,
T. H.; Resinger, C.; Herrman, W. A. Tetrahedron Lett. 1997, 38, 2073-
2074. (e) Brenner, E.; Fort, Y. Tetrahedron Lett. 1998, 39, 5359-5362.
(f) Riermeier, T. H.; Zapf, A.; Beller, M. Top. Catal. 1997, 4, 301-309.
(g) Yamamoto, T.; Nishiyama, M.; Koie, Y. Tetrahedron Lett. 1998, 39,
2367-2370. For related nickel-catalyzed aminations of aryl chlorides,
see: (h) Wolfe, J . P.; Buchwald, S. L. J . Am. Chem. Soc. 1997, 119,
6054-6058. (i) Hong, Y. P.; Tanoury, G. J .; Wildinson, H. S.; Bakale,
R. P.; Wald, S. A.; Senanyake, C. H. Tetrahderon Lett. 1997, 38, 56663-
5666. Also see ref 2f.
Resu lts
I. Syn th esis of Liga n d s 1-10. The ligands 1-10
(Scheme 2) were prepared by utilizing standard syn-
thetic organic methods.13 The ligands 1, 2, 4-7, and 10
were prepared by halogen metal exchange reaction of
appropriate starting aryl bromo precursor with nBuLi
(6) Hartwig, J . F.; Driver, M. S.; Louie, J .; Hamann, B. US patent
5,817,877, 1998.
(7) For a general recent review of palladium- and nickel-catalyzed
aryl aminations, which provides an extensive list of references to the
mechanistic studies and applications of this chemistry, see: (a) Wolfe,
J . P.; Wagaw, S.; Marcoux, J .-F.; Buchwald, S. L. Acc. Chem. Res. 1998,
31, 805-818. (b) Hartwig, J . F. Acc. Chem. Res. 1998, 31, 852-860.
(c) Hartwig, J . F. Angew. Chem., Int. Ed. Engl. 1998, 37, 2046-2067.
More recently reported applications of Pd/L-catalyzed aryl aminations
include: (d) Bolm, C.; Hildebrand, J . P. Tetrahedron Lett. 1998, 39,
5731-5734.
(8) For a general review of metal-initiated aminations, see: Muller,
T. E.; Beller, M. Chem. Rev. 1998, 675, 5-703, and references therein.
(9) Concurrently, DPPF-based nickel catalysts were demonstrated
to be generally useful for the aminations of aryl chlorides; see ref 5h.
Similarly, palladacylces were demonstrated to be effective for the
aminations of aryl chlorides with cyclic secondary amines at higher
temperatures; however, significant amounts of side-products presum-
ably resulting from benzyne intermediates were also observed; see ref
5d.
(10) Our preliminary studies of palladium-catalyzed aminations of
aryl chlorides were recently communicated; see: Bei, X.; Guram, A.
S.; Turner, H. W.; Weinberg, W. H. Tetrahedron Lett. 1999, 40, 1237-
1240.
(11) (a) Danielson, E.; Golden, J . H.; McFarland, E. W.; Reaves, C.
M.; Weinberg, W. H.; Wu, X. D. Nature 1997, 389, 944-948. (b)
Weinberg, W. H.; McFarland, E.; Goldwasser, I.; Boussie, T.; Turner,
H.; van Beek, J . A. M.; Murphy, V.; Powers, T. WO 98/03521, 1998. (c)
Boussie, T. R.; Coutard, C.; Turner, H. W.; Murphy, V.; Powers, T. S.
Angew. Chem., Int. Ed. Engl. 1998, 37, 3272-3274. (d) LaPointe, A.
M. J . Comb. Chem. 1999, 1, 101-104.
(12) These lead ligand structures were identified in
a high-
throughput fashion by conducting reactions in parallel in a micro titer
plate format (48-96 reactions) and screening for performance using
parallel thin layer chromatography (TLC)-based detection methods
(48-56 analyses per TLC plate).

1842 Organometallics, Vol. 18, No. 10, 1999
Bei et al.
Sch em e 2
Ta ble 1. Liga n d Effects in th e P d /
t
or BuLi, followed by quenching of the generated aryl-
lithium intermediate with the desired Ph2PCl or
Cy2PCl electrophile (eq 1), whereas ligands 3 and 8 were
Liga n d -Ca ta lyzed Am in a tion s of 4-Br om obip h en yl
w ith Mor p h olin e a n d Dibu tyla m in ea
amine ) morpholine
amine ) dibutylamine
conversion
(%)
selectivityb
(%)
conversion
(%)
selectivityb
(%)
ligand
1
2
3
4
5
100
100
100
100
10
98
88-98
99
100
62
36-64
10-60
trace
>99 (93)c
16
53-63
16-84
obtained by reductive amination of the 2-(diphenylphos-
phino)benzaldehyde and 2-(dicyclohexylphosphino)-
benzaldehyde with Et2NH/NaB(AcO)3H and Me2NH/
NaB(AcO)3H, respectively (eq 2).14
98
a
Reaction time ) 75 min for morpholine substrate; reaction
time ) 90 min for dibutylamine substrate; reaction tempera-
ture ) 105 °C for all substrates. Conversion and selectivity are
based on GC analysis and are average of 2-4 reactions. A range
is given in cases where the results of two or more identical
b
experiments were substantially different and irreproducible. Se-
lectivity ) [product/(product + reduced S.M.)] × 100. c Isolated
yield.
IIa . P d /L (L ) 1-5)-Ca ta lyzed Am in a tion s of Ar yl
Ha lid es. The Pd(dba)2/L-catalyzed aminations of 4-bro-
mobiphenyl with two different amines, morpholine (a
secondary cyclic amine) and dibutylamine (a secondary
acyclic amine), were chosen as model reactions for
investigating the efficiency of the ligands 1-5 (Table
1).16 For Pd(dba)2/L-catalyzed amination of 4-bromobi-
phenyl with morpholine, ligands 1-4 were all found to
be generally efficient, affording the desired arylamine
in high GC yields.17 However, for the related Pd(dba)2/
L-catalyzed amination of 4-bromobiphenyl with dibu-
tylamine, ligands 1-4 were found to exhibit different
Ligand 9, on the other hand, was prepared by fluoride
ion displacement of 2-(2-fluorophenyl)-4,4-dimethyl-4,5-
dihydrooxazole with LiPCy2.15 Ligands 1-10 were puri-
fied either by recrystallization from deoxygenated al-
cohol solvents (EtOH or MeOH) or by rapid column
chromatography on silica gel using deoxygenated sol-
vents and were obtained as white solids or colorless oils
1
and unambiguously characterized by H, 13C, and 31P
NMR spectroscopy and elemental analysis.
(13) Ligands 1-5 have been synthesized previously. For ligand 1
and 2, see: (a) Schiemenz, G. P.; Kaack, H. Liebigs Ann. Chem. 1973,
1480-1493. (b) Rauchfuss, T. B.; Patino, F. T.; Roundhill, D. Inorg.
Chem. 1975, 14, 652-656. For ligand 3, see: (c) Tomcufcik, A. S.;
Wright, W. B., J r.; Meyer, W. E. US patent 4892885. For ligand 4,
see: (d) Terfort, A.; Brunner, H. J . Chem. Soc., Perkin Trans. 1 1996,
1467-1479. Ligand 5 is commercially available.
(14) 2-(Diphenylphosphino)benzaldehyde was purchased from Ald-
rich Chemical Co., Inc., while 2-(dicyclohexylphosphino)benzaldehyde
was obtained in a quantitative yield from the hydrolysis reaction of
ligand 7; see Experimental Section for details.
(16) Our studies utilized Pd(dba)2 as a source of Pd(0), but other
suitable sources of Pd(0) and/or suitable Pd(II) salts from which Pd(0)
species can be generated in situ could presumably be used. Different
Pd(II) salts have been previously employed in Pd/L-catalyzed aryl
aminations; see refs 1-7.
(17) The efficiency of ligands 1-4 in assisting palladium-catalyzed
amination of 4-bromobiphenyl with morpholine is not shared by other
structurally related phenyl backbone-derived PCCCX ligands (X ) O,
N, S); for example, 2-diphenylphosphinobenzaldehyde and its ben-
zylimine derivative, 2-methyl-2-(2-diphenylphosphinoethyl)-1,3-di-
oxolane, 2-diphenylphosphinobenzophenone, and 1,3-dithiane ana-
logue of 1 and 2 were found to be inefficient under similar reaction
conditions.
(15) The synthesis of the diphenylphosphino analogue of ligand 9
via
a similar fluoride ion displacement route has been described
previously; see: Peer, M.; de J ong, J . C.; Kiefer, M.; Langer, T.; Rieck,
H.; Schell, H.; Sennhenn, P.; Sprinz, J . Steinhagen, H.; Wiese, B.;
Helmchen, G. Tetrahedron 1996, 52, 7547-7583.

(P,O)n-Palladium(II)Aryl(Br) Complexes
Organometallics, Vol. 18, No. 10, 1999 1843
Ta ble 2. P d (d ba )2/Liga n d 1-Ca ta lyzed Am in a tion of Ar yl Ha lid esa
a
Unless noted otherwise, all reactions were performed at 105 °C until complete using 1.0 equiv of aryl halide, 1.1-1.2 equiv of amine,
1.1-1.2 equiv of NaOtBu, 2 mol % Pd(dba)2/6 mol % ligand 1 as catalyst, and toluene as the reaction solvent. Yields reported correspond
b
to isolated material of >95% purity as determined by GC-MS, NMR, and/or elemental analysis. c These reactions were also performed
using 0.5 mol % Pd. Dioxane was used as the reaction solvent. e Diarylated product was also observed.
d
efficiency, with only ligand 1 consistently affording the
desired arylamine in >99% GC yield. Ligand 5 was
found to be inefficient in both reactions.
primary aliphatic amine) were found to be inefficient,
resulting mostly in the formation of the undesired
hydrodehalogenated aryl product. The Pd/ligand 1
catalyst was also not suitable for aminations of aryl
chlorides under otherwise similar conditions; the start-
ing aryl chloride substrate remained mostly unreacted
in these cases. All the isolated arylamine products
obtained from Pd/ligand 1-catalyzed aryl aminations
were unambiguously characterized by GC-MS, 1H and
13C NMR spectroscopy, and elemental analysis.
The utility of the Pd(dba)2/ligand 1 catalyst for the
general aminations of aryl halides was further investi-
gated to determine its scope and limitations. In general,
as illustrated in Table 2, the Pd(dba)2/ligand 1 catalyst
was found to exhibit a wide scope. The Pd/ligand 1
catalyst efficiently catalyzed the reaction of a wide
variety of electron-deficient, electron-rich, and sterically
demanding aryl bromides with a wide variety of second-
ary cyclic (entry B) and acyclic amines (entries A, C, D)
and primary aromatic amines including anilines con-
taining sterically demanding ortho substituents (entries
F-J ).18 The Pd(dba)2/ligand 1 catalyst was found also
to be suitable for the efficient amination of an aryl iodide
(entry E), although a slightly lower yield was obtained.
However, similar aminations involving octylamine (a
IIb. P d /L (L ) 6-10)-Ca ta lyzed Am in a tion s of
Ar yl Ha lid es. The Pd(dba)2/L-catalyzed aminations of
5-chloro-m-xylene with morpholine and N-heptylmeth-
(18) Although, the Pd/ligand 1 catalyst was found to be effective
for the amination of a hindered aryl bromide with aniline (Table 1,
entry H), in general it was found to be unsuitable for aminations of
unhindered aryl bromides with aniline under the conditions investi-
gated.

1844 Organometallics, Vol. 18, No. 10, 1999
Bei et al.
Ta ble 3. Liga n d Effects in th e P d /
Liga n d -Ca ta lyzed Am in a tion s of 5-Ch lor o-m -xylen e
w ith Mor p h olin e a n d N-Hep tylm eth yla m in ea
reactions. The Pd(dba)2/ligand 6 catalyst system was
also found to be equally efficient in catalyzing the
aminations of aryl bromides and iodides with secondary
amines in high selectivity and isolated yields (entries
J ,K, Table 4).22 All the isolated arylamine products
obtained from Pd/ligand 6-catalyzed aryl aminations
were unambiguously characterized by GC-MS, 1H and
13C NMR, and elemental analysis.
amine ) morpholine
conversion selectivityb
amine ) N-heptylmethylamine
III. Isola tion a n d Str u ctu r a l Ch a r a cter iza tion of
P oten tia l Ca ta lytic In ter m ed ia tes. The hemilabile
ligands used in this work contain one P- and at least
one O- or N-binding sites and therefore can function as
P,O- or P,N-chelating ligands. The significantly im-
proved efficiency exhibited by the potentially chelating
ligands 1 and 6 compared to the parent monodentate
nonchelating analogues, PPh3 and PPhCy2, suggests
that the pendant oxygen functionality in ligands 1 and
6 plays a crucial role in the catalytic process.23 The
dramatic difference in efficiency between structurally
very similar ligands 1/6 and 2 (and other closely related
ligands including ligands 3-5, 7-10) is further sugges-
tive of a potential difference in interaction between
ligands 1/6 with the Pd-center compared to ligand-Pd
interactions of other ligands. To gain further insights
into this interesting ligand structure-catalytic perfor-
mance relation, the isolation of potential catalytic
intermediates of the Pd/ligand 1, Pd/ligand 2, and Pd/
ligand 6 catalysts was undertaken.
conversion
(%)
selectivityb
(%)
ligand
(%)
(%)
6
7
8
9
10
100
48-65
30
100
98
98
100
30
100
98
23
98
15
99
5-23
35
86-98
98
35-44
99
a
Reaction time ) 60 min for all substrates; reaction tempera-
ture ) 105 °C for all substrates. Conversion and selectivity are
based on GC analysis and are average values of two or more
experiments. A range is given in cases where the results of two or
more identical experiments were substantially different and
b
irreproducible. Selectivity ) [product/(product + reduced S.M.)]
× 100.
ylamine (a secondary acyclic amine) were chosen as
model reactions for investigation of the efficiency of
ligands 6-10 (Table 3). The presence of a basic dicy-
clohexylphosphine moiety in ligands 6-10 was antici-
pated to increase the electron density at the palladium
center, thereby facilitating the oxidative addition and
thus the subsequent aminations of the usually unreac-
tive aryl chloride substrates.19,20 The Pd(dba)2/L (L )
7-10) catalysts were found to exhibit good selectivity
but low to moderate activity in the aminations of
5-chloro-m-xylene with morpholine and N-methylhep-
tylamine, while the Pd/ligand 6 catalyst was found to
be extremely efficient for both reactions.
a . Isola tion of LP d (4-tBu -C6H4)Br (11, L ) 1; 12,
L ) 6) a n d L2P d (4-tBu -C6H4)Br (13, L ) 2) Com -
p lexes. The complexes 11-13 were formed on contact-
ing Pd2(dba)3 or Pd(dba)2, excess ligand (ligand ) 1, 6,
2), and excess 4-tBu-C6H4Br in toluene solution.24 The
same complexes 11-13 were also formed and more con-
veniently isolated from the ligand displacement reac-
25
tions of complex [Pd{P(o-toluyl)3}(4-tBu-C6H4)(µ-Br)]2
Further studies of Pd(dba)2/ligand 6-catalyzed aryl
aminations revealed the Pd/ligand 6 catalyst to be
generally efficient in catalyzing the amination of a wide
variety of aryl chlorides (Table 4). Aryl chlorides con-
taining both electron-withdrawing and electron-donat-
ing substituents reacted rapidly with a wide variety of
secondary cyclic and acyclic alkylamines to afford the
desired arylamines in very high selectivity and isolated
yields (entries A-D and I, Table 4). These reactions
were essentially complete in 1 h and formed undetect-
able to only trace (less than 1%) amounts of the
undesired hydrodehalogenated product. Aryl chlorides
containing ortho substituents also reacted efficiently
with primary aromatic and aliphatic amines to afford
the desired arylamines in high selectivity and isolated
yields (entries E-H, Table 4). These reactions also
proceeded rapidly and were complete in 3 h.21 Products
resulting from diarylation were not detected in these
with ligands 1, 6, and 2, respectively (eqs 3 and 4).
(21) The Pd(dba)2/ligand 6-catalyzed aminations of aryl chlorides
with primary aliphatic amines is not limited to ortho-substituted aryl
chlorides. Thus, the reaction of 5-chloro-meta-xylene with octylamine
under the conditions described proceeds to completion in 2 h and
affords the desired arylamine. The formation of the undesired hydro-
dehalogenated product was undetectable. However, the diarylated
product was detected (ca. 15-20% by GC-MS) particularly at higher
temperatures.
(22) However, the Pd(dba)2/ligand 6-catalyzed aminations of aryl
bromides appear to be senstive to aryl bromide substrate, and the Pd-
(dba)2/ligand 1 catalyst represents a more general catalyst for aryl
aminations involving aryl bromides.
(23) Pd(dba)2/PPh3 and Pd(dba)2/PPhCy2 are not suitable catalysts
for general aryl aminations of aryl halides. The PdCl2(PCy3)2 catalyst,
although a lead catalyst, was found to be of limited scope and efficiency,
affording low yields of the desired arylamines; see ref 5c.
(24) The analogous complexes LPd(4-Ph-C6H4)Br (L ) 1) and
L2Pd(4-Ph-C6H4)Br (L ) 2) were obtained similarly from the reaction
of 1 equiv of Pd(dba)2, 1.7 equiv of ligand 1 (or ligand 2), and 2.2 equiv
of 4-Ph-C6H4Br at 80 °C in toluene. LPd(4-Ph-C6H4)Br (L ) 1), 31P
NMR (CDCl3, 23 °C): δ 16.8. 1H NMR (CDCl3, 23 °C): δ 7.8-7.0 (m,
19H, ArH), 6.8 (br s, 4H, ArH), 4.73 (br s, 1H, -OCH2CH2O-), 4.15
(br s, 1H, OCH2CH2O), 3.82 (br s, 2H, -OCH2CH2O-), 2.10 (s, 3H,
Me). 1H NMR (CDCl3, 55 °C): δ 7.75 (m, 1H, ArH), 7.7-7.0 (m, 18 H,
ArH), 6.85 (m, 4H, ArH), 4.40 (br s, 2H, -OCH2CH2O-), 3.75 (m, 2H,
-OCH2CH2O-), 2.11 (s, 3H, Me). Anal. Calcd for C34H30BrO2PPd: C,
59.36; H, 4.40; P, 4.50; Pd, 15.47. Found: C, 58.96; H, 4.46; P, 4.62;
Pd, 15.23. L2Pd(4-Ph-C6H4)Br (L ) 2), 1H NMR (C6D6, 23 °C): δ 8.0-
6.5 (m, 39H, ArH + CH), 3.8-3.6 (br AB, 8H, OCH2CH2O). 31P NMR
C6D6, 23 °C): δ 19.8.
(19) Palladium-catalyzed cross-coupling reactions of aryl chlorides
are generally challenging. For notable contributions, see ref 5 and: (a)
Ben-David, Y.; Portnoy, M.; Milstein, D. J . Am. Chem. Soc. 1989, 111,
8742-8744. (b) Ben-David, Y.; Portnoy, M.; Milstein, D. J . Chem. Soc.,
Chem. Commun. 1989, 1816-1817. (c) Gouda, K.; Hagiwara, E.;
Hatanaka, Y.; Hiyama, T. J . Org. Chem. 1996, 61, 7232-7233. For
related nickel-catalyzed cross-coupling reactions, see: (d) Saito, S.; Oh-
tani, S.; Miyaura, N. J . Org. Chem. 1997, 62, 8024-8030. (e) Saito,
S.; Sakai, M.; Miyaura, N. Tetrahedron Lett. 1996, 37, 2993-3996. (f)
Perec, V.; Bae, J . Y.; Hill, D. H. J . Org. Chem. 1995, 60, 1060-1065.
(g) Indolese, A. F. Tetrahedron Lett. 1997, 38, 3513. (h) Grushin, V.
V.; Alper, H. Chem. Rev. 1994, 94, 1047-1062.
(25) The complex [Pd{P(o-tol)3}(4-tBu-C6H4)(µ-Br)]2 was prepared as
described in: (a) Widenhoefer, R. A.; Zhong, H. A.; Buchwald, S. L.
Organometallics 1996, 15, 2745-2754. This complex was prepared
earlier using an alternate route; see: (b) Paul, F.; Patt, J .; Hartwig, J .
F. J . Am. Chem. Soc. 1994, 116, 5969-5970. (c) Hartwig, J . F.; Paul,
F. J . Am. Chem. Soc. 1995, 117, 3030-3039.
(20) This rationale was recently demonstrated to be useful in ligand
design in Pd/L-catalyzed aminations of aryl chlorides; see ref 5.

(P,O)n-Palladium(II)Aryl(Br) Complexes
Organometallics, Vol. 18, No. 10, 1999 1845
Ta ble 4. P d (d ba )2/Liga n d 6-Ca ta lyzed Am in a tion of Ar yl Ch lor id esa
a
Unless noted otherwise, all reactions were performed at 105 °C for 1 h using 1.0 equiv of aryl halide, 1.1-1.2 equiv of amine, 1.1-1.2
equiv of NaOtBu, 2 mol % Pd(dba)2/6 mol % ligand 6 as catalyst, and toluene as the reaction solvent. Yields reported correspond to
b
isolated material of >95% purity as determined by GC-MS, NMR, and/or elemental analysis. c These reactions were also performed
using 0.5 mol % Pd. This reaction was also performed using 0.25 mol % Pd. e 2 h reaction time. f 3 h reaction time. 15 min reaction
d
g
time.
These ligand displacement reactions were performed at
ambient temperature in CH2Cl2 solvent, and the com-
plexes were isolated as solids from concentrated solu-
tions by addition of a hydrocarbon solvent, e.g., pentane
or heptane.
The complexes 11-13 in the solid state are fairly
stable and can be conveniently handled in air. The
complexes 11 and 12 in solution (solvents: toluene-d8,
C6D5Cl, CDCl3) also exhibit good thermal stability. The
complex 11 was observed to decompose at temperatures
above 80 °C in neat toluene-d8 or C6D5Cl, while complex
12 was found to be stable even at 105 °C in neat toluene-
d8. The complexes 11-13 catalyze aryl aminations and
exhibit efficiency similar to that of the corresponding
Pd(dba)2/L (L ) 1, 6, 2) catalyst combinations, respec-
tively.
The X-ray quality crystals of complexes 11-13 were
grown from a methylene chloride/heptane solvent sys-
tem using the layering technique to induce slow crystal-
lization, and the solid-state structures were determined
by single-crystal X-ray diffraction. The molecular struc-
tures of complexes 11-13 are shown in Figures 1, 2,
and 3, respectively, and the crystallographic details and
key bond lengths and bond angles are listed in Tables
5-7.
The complexes 11 and 12 adopt square planar struc-
tures in which ligands 1 and 6 are bound to the Pd-
center through both P and O atoms (Figures 1 and 2
and Table 6). The short Pd-O bond distances of 2.204-
(8) and 2.164(3) Å in complexes 11 and 12, respectively,
conclusively establish the coordination of the O atom
to the Pd-center in these complexes.2e,26 The Pd-P, Pd-
O, Pd-C, and Pd-Br bond distances in complexes 11
b. Solid -Sta te Str u ctu r es of Com p lexes 11-13.

1846 Organometallics, Vol. 18, No. 10, 1999
Bei et al.
respectively. These resonances are significantly down-
field shifted compared to the corresponding resonance
in the 31P NMR spectra of the free ligands 1, 6, and 2
in CDCl3 solvent (δ -9.6, -8.2, and -16.2 ppm, respec-
tively) and establish that the P atom is coordinated to
the Pd-center in these complexes.
The 1H NMR spectra of complexes 11 and 12 in CDCl3
exhibit characteristic resonances for the -OCH2CH2O-
group. For complex 11, the -OCH2CH2O- protons
appear as three broad resonances at δ 4.70, 4.21, and
3.85 in a 1:1:2 ratio,27 whereas for complex 12, the
analogous -OCH2CH2O- protons appear as four reso-
nances at δ 4.71, 4.12, 3.81, 3.71 in a 1:1:1:1 ratio. For
both complexes 11 and 12, the -OCH2CH2O- proton
resonances are downfield shifted compared with the
corresponding resonances of the free ligands (3.72 and
3.20 for ligand 1 and 4.02 and 3.73 for ligand 6). This
indicates that one O atom of the -OCH2CH2O- group
in both complexes 11 and 12 is coordinated to the Pd
center.28,29
Unlike the 1H NMR spectrum of complexes 11 and
1
12, the H NMR spectrum of complex 13 exhibits two
sharper resonances at δ 4.11 and 3.95 in a 4:4 ratio for
two -OCH2CH2O- groups. These resonances are nearly
identical to those observed for the free ligand 2 (δ 4.21
and 3.98 ppm), establishing a lack of coordination of any
O atom to the Pd-center and the presence of two
P-coordinated ligands 2 in complex 13.30 The presence
of only a single sharp resonance in the 31P NMR
spectrum of complex 13 further indicates that the two
phosphine ligands adopt a trans configuration which
makes them equivalent.
Collectively, the solution NMR data for complexes
11-13 are consistent with the observed solid-state
structures and indicate that complexes 11-13 maintain
the observed solid-state structures in solution.
and 12 are generally similar to each other and are also
similar to the corresponding bond distances observed
in the previously reported ferrocenyl-based (P,O)-Pd
complex, (PPFOMe)Pd(4-tBu-C6H4)Br.2e The P-Pd-O
bite angle in complexes 11 and 12 is also similar (85.7-
(2)° and 84.95(9)°, respectively), but is smaller than the
P-Pd-O angle observed in the (PPFOMe)Pd(4-tBu-
C6H4)Br complex (90.5(2)°).2e
The complex 13 also adopts a square planar structure,
but in this case the two molecules of ligand 2 occupy
trans positions each coordinating to the Pd-center only
through its P atom with no close Pd-O contacts (Figure
3 and Table 7). The Pd-P, Pd-C, and Pd-Br bond
lengths are slightly longer than the corresponding bond
lengths observed in complexes 11 and 12, presumably
due to the presence of two sterically demanding ligands.
c. Solu tion Str u ctu r es of Com p lexes 11-13. The
solution structures of complexes 11-13 were established
by the solution NMR spectroscopic studies. The 31P
NMR spectra of complexes 11-13 in CDCl3 solvent
exhibit a single resonance at δ 16.3, 28.5, and 18.0 ppm,
Discu ssion
The results illustrated above clearly establish that the
simple and readily accessible31 phenyl backbone-derived
P,O-ligands 1 and 6 effectively assist general Pd/L-
(27) A similar 1H NMR resonance pattern is also observed for
the analogous complex LPd(4-Ph-C6H4)Br (L ) 1); see ref 24 for
details.
(28) At higher temperatures, the resonances for the -OCH2CH2O-
group of both complexes 11 and 12 broaden and coalesce to afford only
two resonances in 2:2 ratio (chemical shifts can be found in the
Experimental Section), which presumably results from rapid exchange
of the O-Pd coordination between the two O atoms. Such broadening
and coalescence of the resonances of the -OCH2CH2O- group appear
to be facilitated in the presence of amines (N-methylbenzylamine,
morpholine) and in C6D5Cl (for complex 11).
(29) Although the data support coordination of the O atom of the
-OCH2CH2O- to the Pd-center in complex 11 and 12, it does not
preclude the dissociation of the O atom from the Pd-center under
catalysis conditions. The rapid exchange of O-Pd coordination between
the two O atoms at higher temperatures and in the presence of certain
additives suggests that the O atoms remain in close proximity to the
Pd-center at all times. Attempts to synthesize, isolate, and characterize
Pd(0)Ln, Pd(II)(Ln)ArX (X ) OtBu, NR2) and related complexes were
unsuccessful, and thus it is not clear if such O-Pd coordination is also
present in these subsequent catalytic intermediates.
(26) These bond distances compare favorably to the Pd-O covalent
bond distances observed for square planar complexes of palladium;
see: (a) Bryndza, H. E.; Tam, W. Chem. Rev. 1988, 88, 1163-1188.
(b) Kiers, N. H.; Feringa, B. L.; Kooijman, H.; Spek, A. L.; van Leeuwen,
P. W. N. M. J . Chem. Soc., Chem. Commun. 1992, 1169-1170. (c)
Kapteijn, G. M.; Grove, D. M.; Kooijman, H.; Smeets, W. J .; Spek, A.
L.; van Koten, G. Inorg. Chem. 1996, 35, 526-533.
(30) A similar 1H NMR resonance pattern is also observed for the
analogous complex L2Pd(4-Ph-C6H4)Br (L ) 2); see ref 24 for details.
(31) As described in the results section, ligands 1 and 6 are read-
ily available in two high-yield synthetic steps from inexpen-
sive commercially available starting materials. Ligands 1 and 6 are
isolated as stable colorless solids and can be conveniently handled in
air.

(P,O)n-Palladium(II)Aryl(Br) Complexes
Organometallics, Vol. 18, No. 10, 1999 1847
ary cyclic and acyclic alkylamines to afford the desired
arylamines in high isolated yields. The efficiency of the
Pd/ligand 1 catalyst for aminations of aryl bromides
with secondary acyclic alkylamines is particularly no-
table because such aryl aminations are generally dif-
ficult to achieve. Overall, the Pd/ligand 1 catalyst
exhibits catalytic performance similar to that of the
structurally related, but ferrocenyl backbone-derived,
Pd/PPFOMe and Pd/PPFA catalysts,2e which previously
were the only catalysts suitable for aminations of aryl
bromides with secondary acyclic alkylamines. Like the
Pd/PPFOMe and Pd/PPFA catalysts, the Pd/ligand 1
catalyst does not appear to be suitable for the general
aminations of aryl bromides and iodides with primary
alkylamines, of aryl chlorides, and involving parent
unsubstituted aniline under otherwise standard condi-
tions.
The observed similarity in catalytic performance
between the Pd/ligand 1 catalyst and the Pd/PPFOMe
and Pd/PPFA catalysts may not be surprising given the
similarity of structures of the ligands involved, i.e., the
presence of a rigid PCCCX (X ) O, N) unit. However,
the observed difference in efficiency between the Pd/
ligand L (L ) 1, PPFOMe and PPFA) catalysts and the
Pd/ligand L (L ) 2, 3, 4, and other related ligands)
catalysts is immensely surprising given the closer
resemblance of ligands 3/4 to ligands PPFOMe/PPFA,
respectively. The difference in efficiency between the Pd/
ligand 1 catalyst and the Pd/ligand 2 catalyst is par-
ticularly remarkable given the nearly identical struc-
tures of ligands 1 and 2. These differences in reactivity
most likely result due to the generation and involvement
of structurally different catalytic intermediates in each
of the Pd/L catalyst systems. This is consistent with the
isolation and characterization of structurally different
complexes 11 and 13. In complex 11, one molecule of
ligand 1 coordinates to the Pd-center via both P and O
atoms and exhibits a structure similar to that of the
Pd/PPFOMe complex; while in complex 13, two mol-
ecules of ligand 2 coordinate to the Pd-center in a trans
fashion each via only the P atom. Such trans P atom
coordinated “Pd(P)2” organometallic structures may also
be generated in other Pd/ligand L (L ) 3-5) catalysts
and may be responsible for the observed inefficiency of
such catalysts in the aryl aminations involving certain
substrates and conditions.
Figu r e 1. Molecular structure and atom-numbering scheme
of complex 11 (molecule 1).
Figu r e 2. Molecular structure and atom-numbering scheme
of complex 12.
The Pd/ligand 6 catalyst, on the other hand, efficiently
catalyzes the aminations of a variety of aryl chlorides
with a variety of primary aromatic amines and second-
ary cyclic and acyclic alkylamines to afford the desired
arylamines in high isolated yields. In general, the Pd/
ligand 6-catalyzed aryl aminations are characterized by
high rates and selectivity, and the undesired reduced
products are either undetectable or formed in only trace
amounts. The Pd/ligand 6 catalyst is also efficient for
the amination of ortho-substituted aryl chlorides with
primary alkylamines, however lack of ortho substitution
on the aryl halide substrate results in the formation of
the diarylated primary alkylamine byproduct. The
formation of diarylated byproduct is minimized at lower
reaction temperatures and higher concentrations of the
Figu r e 3. Molecular structure and atom-numbering scheme
of complex 13.
catalyzed aminations of aryl bromides, iodides, and
chlorides.32
(32) While ligands 1 and 6 exhibit the best efficiency, ligands 2-4,
7-10 are also potentially suitable candidates and may exhibit equal
or better aryl amination efficiency with other substrates and/or under
other reaction conditions.
The Pd/ligand 1 catalyst efficiently catalyzes the
aminations of a variety of aryl bromides and iodides
with a variety of primary aromatic amines and second-

1848 Organometallics, Vol. 18, No. 10, 1999
Ta ble 5. Cr ysta l Da ta a n d Str u ctu r e Refin em en t P a r a m eter s for Com p lexes 11-13a
Bei et al.
11
12‚CH2Cl2
13‚C7H16
empirical formula
MW
temp
wavelength
cryst syst
space group
unit cell dimens
C32H34BrO2PPd
667.87
295(2) K
0.717 073 Å
triclinic
P1h
C32H46BrO2PPd‚CH2Cl2
C59H67BrO4P2Pd
764.89
1088.38
173(2) K
0.710 73 Å
triclinic
P1h
295(2) K
0.710 73 Å
triclinic
P1h
a ) 11.055(2) Å R ) 89.45(1)° a ) 11.254(1) Å R ) 105.46(1)° a ) 12.909(1) Å R ) 75.498(6)°
b ) 20.160(5) Å â ) 81.95(2)°
c ) 20.521(3) Å γ ) 80.80(2)°
4469.8(1.4) Å3
b ) 11.565(2) Å â ) 94.38(1)°
c ) 14.104(2) Å γ ) 95.93(1)°
1749.5(4) Å3
b ) 13.850(1) Å â ) 74.335(5)°
c ) 17.241(1) Å γ ) 69.703(6)°
2741.5(4) Å3
volume
Z
6
2
2
density (calcd)
abs coeff
1.489 g/cm3
1.452 g/cm3
1.319 g/cm3
20.44 cm-1
18.98 cm-1
11.7 cm-1
F(000)
2028
784
1128
cryst size
θ range for data collection
index ranges
0.3 × 0.07 × 0.4 mm
0.18 × 0.20 × 0.36 mm
0.24 × 0.34 × 0.36 mm
2.00-20.00°
2.03-25.00°
2.64-22.50°
0 e h e 10, -19 e k e 19,
-19 e l e 19
8837
8263 (Rint ) 0.0436)
full-matrix least-squares on F2
7291/0/1012
-1 e h e 13, -13 e k e 13,
-16 e l e 16
7068
6055 (Rint ) 0.0262)
full-matrix least-squares on F2
5482/42/397
0 e h e 13, -13 e k e 14,
-17 e l e 18
7395
7026 (Rint ) 0.043)
full-matrix least-squares on F2
6373/53/609
no. of reflns collected
no. of ind reflns
refinement method
no. of data/restraints/params
goodness-of-fit on F2
final R indices (all data)
R indices (all data)
largest diff peak and hole
extinction coeff
1.039
1.019
1.048
R1 ) 0.0572, wR2 ) 0.1172
R1 ) 0.1178, wR2 ) 0.1443
0.968 and -0.517 e Å-3
R1 ) 0.0428, wR2 ) 0.0732
R1 ) 0.0839, wR2 ) 0.0853
0.490 and -0.394 e Å-3
0.0006(2)
R1 ) 0.0604, wR2 ) 0.1521
R1 ) 0.1022, wR2 ) 0.1783
1.299 and -0.428 e Å-3
R1 ) ||Fo| - |Fc||/|Fo|, wR2 ) [(wi(Fo - Fc2)2)/(wi(Fo2)2)]1/2, GOF ) [(wi(Fo - Fc2)2)/(n - p)]1/2
.
a
2
2
Ta ble 6. Selected Bon d Len gth s a n d Bon d An gles
of Com p lexes 11 a n d 12
to those of Pd/ligand 1 catalyst. This is consistent with
the isolation and characterization of complex 12. Like
complex 11, complex 12 contains one molecule of ligand
6 coordinated to the Pd-center via both the P and O
atoms.
bond lengths
bond angles
11
12
11
12
Pb-Br 2.475(2) 2.4678(12) Br-Pd-O1
93.8(2)
85.7(2)
89.0(4)
90.16(9)
84.95(9)
94.34(13)
90.64(13)
178.1(2)
Pd-O1 2.204(8) 2.164(3)
O1-Pd-P
The efficiency of the Pd/ligand 1 and Pd/ligand 6
catalysts for aryl aminations can be ascribed to the
structures of ligands 1 and 6, which presumably favor
the generation and stability of the chelating “(P,O)-Pd”
intermediates, consistent with the isolation of interme-
diates 11 and 12. The unique efficiency of Pd/ligand L
(L ) 1, 6, PPFOMe,2e and PPFA2e) suggests that the
chelating “(P,X)-Pd” (X ) O, N) intermediates may play
an important role in the catalytic process.34 The poten-
tial role of structurally related P,O- and P,N-ligands in
beneficially influencing the Pd/L-catalyzed aryl amina-
tions of aryl bromides has been discussed previously by
the Buchwald group.2e The higher efficiency of the Pd/
ligand 6 catalyst, particularly for the aminations of aryl
chlorides, can be attributed to the dicyclohexylphos-
phino group, which makes the Pd-center sufficiently
electron rich to promote oxidative addition of the usually
unreactive aryl chloride substrates.
Pd-P
2.236(4) 2.273(2)
Pd-C23 1.972(13) 1.979(4)
P-Pd-C23
C23-Pd-Br 91.6(4)
C23-Pd-O1 174.3(5)
P-Pd-Br
177.67(11) 174.09(4)
Ta ble 7. Selected Bon d Len gth s a n d Bon d An gles
of Com p lex 13
bond lengths
bond angles
Pd-Br
2.5378(7)
2.3478(14)
2.3514(14)
2.001(4)
P-Pd-C43
86.5(2)
89.8(2)
91.11(3)
92.53(4)
178.15(12)
176.29(5)
Pd-P1
Pd-P2
Pd-C43
C43-Pd-P2
P2-Pd-Br
Br-Pd-P1
C43-Pd-Br
P1-Pd-P2
primary amine. Furthermore, unlike the Pd/ligand 1
catalyst, the Pd/ligand 6 catalyst is also suitable for the
aryl aminations involving unhindered primary aromatic
amines.
The effectiveness of the Pd/ligand 6 catalyst in the
aminations of aryl chlorides is generally superior to that
of the previously described Pd/PCy3, palladacycle, Pd/
PtBu3,33 and Ni/DPPF catalysts and similar to that of
the recently described naphthyl-derived Pd/P,N (P,N )
DCPA-BINAP) and the ferrocenyl-derived Pd/P,P (P,P
) DBtPF, PPFBtP, DCPFDCP) catalysts. However, the
Pd/ligand 6 catalyst and the recent Pd/P,N (P,N )
DCPA-BINAP) catalyst currently represent the only two
suitable catalysts for efficient aminations of aryl chlo-
rides with secondary acyclic alkylamines.
(34) The Pd/L-catalyzed (e.g., L ) P(o-toluyl)3, DPPF, BINAP) aryl
aminations proceed via oxidative addition of an aryl halide, forma-
tion of an “Pd(Ar)(amide)” intermediate, and reductive elimination of
the arylamine. This mechanism has been postulated and studied
extensively, independently by the groups of Buchwald and Hartwig;
see refs 2a-d, 24, and: (a) Driver, M. S.; Hartwig, J . F. J . Am. Chem.
Soc. 1995, 117, 4708-4709. (b) Driver, M. S.; Hartwig, J . F. J .
Am. Chem. Soc. 1997, 119, 8232-8245. (c) Mann, G.; Hartwig, J . F. J .
Am. Chem. Soc. 1996, 118, 13109-13110. (d) Driver, M. S.; Hartwig,
J . F. J . Am. Chem. Soc. 1996, 118, 4206-4207. (e) Driver, M. S.;
Hartwig, J . F. Organometallics 1997, 16, 5706. (f) Widenhoefer, R. A.;
Buchwald, S. L. Organometallics 1996, 15, 2755-2763. (g) Widen-
hoefer, R. A.; Buchwald, S. L. Organometallics 1996, 15, 3534-3542.
For general chelate effect of structure and activity and mechanistic
studies of oxidative addition of aryl chlorides to Pd(0)Ln complexes,
see: (h) Portnoy, M.; Milstein, D. Organometallics 1993, 12, 1655-
1664. (i) Portnoy, M.; Milstein, D. Organometallics 1993, 12, 1665-
1673.
The aryl aminations catalyzed by Pd/ligand 6 catalyst
most likely involve organometallic intermediates similar
(33) Pd/PtBu3 is the most efficient catalyst to date for the aryl
aminations of aryl bormides with biarylamines; see refs 2f and 5g.

(P,O)n-Palladium(II)Aryl(Br) Complexes
Organometallics, Vol. 18, No. 10, 1999 1849
none (5.08 g, 25.5 mmol), ethylene glycol (6.64 g, 106 mmol),
and p-toluenesulfonic acid monohydrate (0.1 g, 0.5 mmol) in
benzene (60 mL) was heated at reflux for 24 h using a Dean
Stark setup to remove water. The reaction mixture was taken
up in methylene chloride (100 mL) and washed with water (3
× 25 mL) and brine (25 mL). The organic phase was dried over
magnesium sulfate and concentrated under vacuum to afford
2-(2′-bromophenyl)-2-methyl-1,3-dioxalane (yield: 5.99 g, 97%)
as a pale yellowish oil, which was found to be of >95% purity
Con clu sion s
The phenyl backbone-derived ligands 1 and 6 in
combination with Pd(dba)2 afford active catalysts for the
efficient amination of aryl bromides, iodides, and chlo-
rides. The efficiency of ligands 1 and 6 in Pd/L-catalyzed
aryl aminations results from the presence of the R2P
(R ) Ph, Cy) and ketal groups on a rigid phenyl
backbone which presumably allow for the generation
and stability of P,O-chelating palladium-ligand com-
plexes. Such P,O-chelating palladium-ligand complexes
appear to be most suitable for aryl aminations involving
certain substrates. However, the mere presence of P and
O atoms in the ligand framework does not necessarily
provide efficient ligands for Pd/L-catalyzed aryl amina-
tions. Minor differences in ligand structures can lead
to major differences in catalytic efficiency due to the
generation of quite different palladium-ligand com-
plexes.
Overall, the efficiency of the Pd/ligand 1 and Pd/ligand
6 catalysts for aryl aminations involving primary aro-
matic amines and secondary cyclic and acyclic amines
is generally superior to that of Pd/P(o-toluyl)3, Pd/PCy3,
Pd/P(tBu)3, and palladacycle catalysts. For aminations
of aryl bromides with secondary acyclic amines, the Pd/
ligand 1 catalyst efficiency is also superior to that of
Pd/DPPF and Pd/BINAP and is equal to that of Pd/
PPFOMe and Pd/PPFA catalysts. For aminations of aryl
chlorides with secondary acyclic amines, the Pd/ligand
6 catalyst efficiency is superior to that of the ferrocenyl-
derived Pd/L catalysts (L ) DBtPF, PPFBtP, DCPFDCP)
and is similar to that of the binaphthyl-derived Pd/L
catalyst (L ) DCPA-BINAP). Moreover, the ready
accessibility and low cost of ligands 1 and 6 compared
to the binaphthyl- and ferrocenyl-derived ligands make
ligands 1 and 6 more attractive candidates for general
Pd/L-catalyzed aryl aminations.35
1
by H and GC-MS analysis.
P ar t II. The 2-(2′-bromophenyl)-2-methyl-1,3-dioxalane (5.99
g, 24.6 mmol) was dissolved in anhydrous diethyl ether (60
mL), and the solution was cooled to -78 °C. n-Butyllithium
(15.6 mL, 1.6 M solution in hexane, 25 mmol) was added
dropwise with stirring. The reaction mixture was stirred for
2 h at -78 °C. Chlorodiphenylphosphine (6.60 g, 0.030 mol)
was added dropwise via a syringe at -78 °C with stirring. The
reaction mixture was allowed to warm to room temperature
and stirred for an additional 18 h. The reaction mixture was
taken up in methylene chloride (150 mL) and washed under
inert atmosphere with 0.5 M degassed sodium hydroxide
solution and water (50 mL). The organic phase was concen-
trated under vacuum to afford a yellowish solid. The yellowish
solid was recrystallized from hot ethanol to afford ligand 1
(7.10 g, 83% yield) as a crystalline white solid. Alternatively,
ligand 1 may be purified by rapid column chromatography on
silica gel using 4:1 hexanes/ethyl acetate as eluent. 31P{1H}
NMR (CDCl3): δ -9.6. 1H NMR (CDCl3): δ 7.70 (m, 1H, ArH),
7.5-7.2 (m, 12H, ArH), 7.09 (m, 1H, ArH), 3.72 (m, 2H,
-OCH2CH2O-), 3.20 (m, 2H, -OCH2CH2O-), 2.02 (s, 3H,
-CH3). 13C{1H} NMR (CDCl3): δ 147.9 (d, J PC ) 23), 138.6 (d,
J PC ) 12), 135.8, 134.6 (d, J PC ) 25), 133.8, 133.5, 128.6, 128.1
(m, 2C), 126.2 (d, J PC ) 6), 109.8 (-OCO-), 63.9 (OCH2), 28.0
(CH3). Anal. Calcd for C22H21O2P: C, 75.85; H, 6.08; P, 8.89.
Found: C, 75.83; H, 6.38; P, 8.73.
2-(2′-Diph en ylph osph in oph en yl)-1,3-dioxolan e (Ligan d
2).13a,b Ligand 2 (white crystalline solid) was prepared from
2-bromobenzaldehyde by the procedure described for the
preparation of ligand 1. 31P{1H} NMR (CDCl3): δ -16.2. 1H
NMR (CDCl3): δ 7.73 (d/d, J ) 7.5/3.9, 1H, ArH), 7.43 (t, J )
7.5, 1H, ArH), 7.4-7.2 (m, 11H, ArH), 7.00 (d/d, J ) 7.2/4.2,
1H, ArH), 6.47 (d, J PH ) 4.8, CH), 4.12 (m, 2H, -OCH2CH2O-
), 3.98 (m, 2H, -OCH2CH2O-). 13C{1H} NMR (CDCl3): δ 142.0
(d, J PC ) 21), 137.0 (d, J PC ) 10), 135.4 (d, J PC ) 19), 134.0,
133.8, 133.6, 129.2 (d, J PC ) 13), 128.5 (d, J PC ) 6), 128.4 (d,
J PC ) 7), 126.4 (d, J PC ) 6), 101.7 (d, J PC ) 24, -OCO-), 65.4
(-OCH2-). Anal. Calcd for C21H19O2P: C, 75.44; H, 5.73; P,
9.26. Found: C, 75.64; H, 5.88; P, 9.15.
Exp er im en ta l Section
Gen er a l Com m en ts. All reactions were performed under
an argon atmosphere in oven-dried glass Schlenk tubes using
standard Schlenk techniques. All aryl halides, all amines,
sodium tert-butoxide, bis(dibenzylideneacetone)palladium, ben-
zene, ethanol, diethyl ether, methylene chloride, toluene, and
1,4-dioxane were purchased from commercial sources and used
as such. {Pd[P(o-toluyl)3](4-tBu-C6H4)(µ-Br)}2 was prepared
according to literature procedures.25 All solvents were of the
anhydrous, sure-seal grade. Column chromatography was
performed using commercially available Silica Gel 60 (particle
size: 0.063-0.100 mm), hexanes, and ethyl acetate. GC-MS
analyses were conducted on a Hewlett-Packard 6890 instru-
ment. 1H, 13C, and 31P NMR spectra were obtained using a
Bruker 300 MHz FT-NMR spectrometer. Chemical shifts in
1H and 13C NMR spectra were calibrated with reference to the
chemical shift of residual protiated solvent. Chemcial shifts
in 31P NMR spectra were calibrated with reference to 85%
H3PO4; a negative value of chemical shift denotes resonance
upfield from H3PO4. Coupling constants are reported in hertz.
Elemental analyses were performed by E & R Microanalytical
Laboratory, Inc., NJ .
o-Diph en ylph osph in o-N,N-dieth ylben zylam in e (Ligan d
3).13c To a degassed mixture of 2-diphenylphosphinobenzal-
dehyde (310 mg, 1.07 mmol) and sodium triacetoxyborohydride
(272 mg, 1.28 mmol) was added methylene chloride (10 mL).
Diethylamine (1.0 mL, excess) was added via syringe to the
reaction slurry at room temperature and the reaction mixture
stirred for 30 min at room temperature and then 30 min at 40
°C. The reaction color changed from yellow to colorless. The
reaction mixture was cooled to room temperature and concen-
trated under vacuum. The residue was filtered through a short
column of silica gel using 4:1 hexanes/ethyl acetate as the
eluent. Removal of solvents afforded ligand 3 (360 mg, 96%
yield) as a colorless to pale yellow oil. 31P{1H} NMR (CDCl3):
δ -14.6. 1H NMR (CDCl3): δ 7.5 (m, 1H, ArH), 7.3-7.1 (m,
11H, ArH), 7.05 (t/d, J ) 7.5/1.2, 1H, ArH), 6.79 (d/d/d, J )
7.5/4.2/1.5, 1H, ArH), 3.67 (d, J ) 2.1, 2H, -NCH2-), 2.32 (q,
J ) 7.2, 4H, -NCH2CH3), 0.75 (t, J ) 7.2, 6H, 2 CH3’s).
3-(2′-Dip h en ylp h osp h in op h en yl)-2-oxa bu ta n e (Liga n d
4).13d Ligand 4 (off-white crystalline solid) was prepared from
3-(2′-bromophenyl)-2-oxabutane by the procedure described in
part II for the preparation of ligand 1. 31P{1H} NMR (CDCl3):
2-(2′-Dip h en ylp h osp h in op h en yl)-2-m et h yl-1,3-d ioxo-
la n e (Liga n d 1).13a,b P a r t I. A solution of 2-bromoacetophe-
(35) We have found these catalysts to be also useful for other metal-
catalyzed reactions. For applications of such catalyst in Suzuki biaryl
couplings involving aryl chlorides, see: Bei, X.; Crevier, T.; Guram,
A. S.; J andeleit, B.; Powers, T. S.; Turner, H. W.; Uno, T.; Weinberg,
W. H. Tetrahedron Lett., in press.
1
δ -16.1. H NMR (CDCl3): δ 7.59 (d/d, J ) 7.8/4.2, 1H, ArH),
7.42 (t, J ) 7.7, 1H, ArH), 7.41-7.25 (m, 10H, ArH), 7.20 (t/d,

1850 Organometallics, Vol. 18, No. 10, 1999
Bei et al.
J ) 7.5/1.2, 1H, ArH), 6.93 (d/d/d, J ) 7.5/6/1, 1H, ArH), 5.18
(pentet, 2J HH ) 3J PH ) 6.3, 1H, -CHCH3), 3.11 (s, 3H, -OCH3),
1.30 (d, J ) 6.3, 3H, -CHCH3). 13C{1H} NMR (CDCl3): δ 148.4
(d, J PC ) 26), 136.8 (d, J PC ) 10), 136.3 (d, J PC ) 10), 134.8 (d,
J PC ) 14), 134.2 (d, J PC ) 20), 133.8 (d, J PC ) 20), 133.3, 129.5,
128.8, 128.7, 128.5 (d, J PC ) 6), 128.4 (d, J PC ) 5), 127.4, 125.5
(d, J PC ) 5), 76.1 (d, J PC ) 26, -CHCH3), 56.3 (-OCH3), 23.4
(CHCH3). Anal. Calcd for C21H21OP: C, 78.73; H, 6.61; P, 9.67.
Found: C, 78.70; H, 6.83; P, 9.57.
o-Dip h en ylp h osp h in oa n isole (Liga n d 5). Ligand 5 (off-
white crystalline solid) was prepared from the sequential
reaction of o-bromoanisole, tBuLi, and Ph2PCl by the procedure
described for the preparation of ligand 7. Ligand 5 is also
commercially available. 31P{1H} NMR (CDCl3): δ -15.5. 1H
NMR (CDCl3): δ 7.35-7.15 (m, 11H, ArH), 6.90-6.78 (m, 2H,
ArH), 6.68-6.60 (m, 1H, ArH), 3.70 (s, 3H, -OCH3).
2-(2′-Dicycloh exylp h osp h in op h en yl)-2-m et h yl-1,3-d i-
oxola n e (Liga n d 6). 2-(2′-Bromophenyl)-2-methyl-1,3-diox-
alane (2.02 g, 8.31 mmol) was dissolved in anhydrous diethyl
ether (30 mL), and the solution was cooled to -78 °C.
n-Butyllithium (5.7 mL, 1.6 M solution in hexane, 9.13 mmol)
was added dropwise with stirring. The reaction was stirred
for 2 h. Chlorodicyclohexylphosphine (2.32 g, 9.96 mmol) was
added dropwise via a syringe at -78 °C with stirring. The
reaction mixture was allowed to warm to room temperature
and stirred for an additional 18 h. To the reaction mixture
was added argon-purged water (25 mL) slowly. The organic
phase was separated under argon, and the aqueous phase was
washed with diethyl ether (20 mL). The combined organic
phase was concentrated under vacuum to afford a colorless
oil, which was crystallized from methanol to afford ligand 6
as a white crystalline solid (yield: 2.13 g, 71% unoptimized
yield). 31P{1H} NMR (CDCl3): δ -8.2. 1H NMR (CDCl3): δ 7.67
(br 1H, ArH), 7.59 (br, 1H, ArH), 7.29 (br, 2H, ArH), 4.02 (m,
2H, -OCH2CH2O-), 3.73 (m, 2H, -OCH2CH2O-), 1.97-1.15
(br m, 25H, CyH and CH3). 13C NMR (CDCl3): δ 149.3 (d, J PC
organic phase was concentrated under vacuum, affording a
yellow oil. The crude product was purified by column chroma-
tography on silica gel using hexanes/ethyl acetate (8:1) as the
eluent to afford o-dicyclohexylphosphinobenzaldehyde as a
yellow oil (yield: 740 mg, 85%).
P a r t II. To an air-free slurry of sodium triacetoxyborohy-
dride (523 mg, 2.47 mmol) in methylene chloride (10 mL) and
o-dicyclohexylphosphinobenzaldehyde (370 mg, 1.23 mmol)
was added a solution of NMe2H (5 mL, 2.0 M in THF) at room
temperature, and the mixture was stirred for 30 min. Deoxy-
genated H2O (10 mL) was added slowly to the reaction mixture
with stirring. The organic phase was separated and concen-
trated under vacuum, affording ligand 8 as a colorless oil in
1
quantitative yield. 31P{1H} NMR (CDCl3): δ -16.7. H NMR
(CDCl3): δ 7.52 (d/d, J ) 7.5/3.6, 1H, ArH), 7.41 (d, J ) 7.2,
1H, ArH), 7.29 (t/d, J ) 7.2/0.9, 1H, ArH), 7.20 (t/d, J ) 7.5/
1.2, 1H, ArH), 3.82 (d, J PH ) 2.7, 2H, -NCH2), 2.25 (s, 6H,
NMe2), 2.0-0.9 (m, 22H, CyH). 13C{1H} NMR (CDCl3): δ 146.0
(d, J PC ) 23), 134.3 (d, J PC ) 20), 132.2 (d, J PC ) 3), 129.4 (d,
J PC ) 5), 128.5, 125.8, 61.3 (d, J PC ) 25), 45.1, 34.0 (d, J PC
)
13), 30.3 (d, J PC ) 17), 29.1 (d, J PC ) 12), 27.0 (m, 2C), 26.3.
Anal. Calcd for C21H34NP: C, 76.09; H, 10.34; P, 9.34. Found:
C, 76.39; H, 10.65; P, 9.72.
2-(2-Dicycloh exylp h osp h in op h en yl)-4,4-d im eth yl-4,5-
d ih yd r ooxa zole (Liga n d 9). A solution of dicyclohexylphos-
phine (2.74 g, 13.8 mmol) in tetrahydrofuran (20 mL) was
cooled to -78 °C. A solution of n-butyllithium (9.08 mL. 1.6
M in hexanes) was added dropwise with stirring. The reaction
mixture was stirred for 30 min at -78 °C and was allowed to
warm to -20 °C over 2.5 h. A solution of 2-(2-fluorophenyl)-
4,4-dimethyloxazole (1.86 g, 9.70 mmol) in tetrahydrofuran (10
mL) was added to the mixture, and the mixture was stirred
and allowed to warm to room temperature. The mixture was
concentrated under vacuum. The product was purified by rapid
column chromatography on silica gel using 4:1 hexanes/ethyl
acetate as eluent, yielding ligand 9 in a quantitative yield. 31P-
1
) 23), 134.8 (d, J PC ) 28), 134.0, 128.0, 127.1, 125.4 (d, J PC
)
{1H} NMR (CDCl3): δ -5.8. H NMR (CDCl3): δ 7.55 (m, 2H,
6), 109.6 (-OCO-), 64.0 (-OCH2-), 36.3 (d, J PC ) 15), 30.8
(d, J PC ) 18), 30.0 (d, J PC ) 11), 29.4 (d, J PC ) 14), 27.4 (d, J PC
) 9), 27.2 (d, J PC ) 12), 26.4. Anal. Calcd for C22H33O2P: C,
73.30; H, 9.23; P, 8.59. Found: C, 73.50; H, 9.46; P, 8.36.
1-(2′-Dicycloh exylp h osp h in op h en yl)-1,1-d im et h oxy-
m eth a n e (Liga n d 7). o-Dimethoxymethylbromobenzene (4.13
g, 17.9 mmol) was dissolved in anhydrous diethyl ether (60
mL), and the solution was cooled to -78 °C. tert-Butyllithium
(21.2 mL, 1.7 M solution in hexane, 36 mmol) was added drop-
wise with stirring. The reaction was stirred for 1 h. Chlorodi-
cyclohexylphosphine (5.0 g, 21.5 mmol) was added dropwise
via a syringe at -78 °C with stirring. The reaction mixture
was allowed to warm to room temperature over an additional
18 h. To the mixture was added deoxygenated water (40 mL)
slowly. The organic phase was separated under argon, and the
aqueous phase was washed with diethyl ether (20 mL). The
combined organic phase was dried under vacuum at 40 °C.
The crude product was washed with methanol (3 × 10 mL)
and dried under vacuum, affording ligand 7 as a white solid
ArH), 7.38 (m, 2H, ArH), 4.14 (s, 2H, OCH2), 2.2-0.9 (m, 28H,
CyH and CMe2). 13C{1H} NMR (CDCl3): δ 164.1, 136.4 (d, J PC
) 28), 132.5, 130.3 (d, J PC ) 35), 129.4 (d, J PC ) 7), 129.0,
128.2, 79.1, 67.7, 34.3 (d, J PC ) 13), 30.2 (d, J PC ) 17), 29.6 (d,
J PC ) 11), 28.2, 27.1 (m, 2C), 26.3. Anal. Calcd for C23H34
-
NOP: C, 74.36; H, 9.22; P, 8.34. Found: C, 74.36; H, 9.14; P,
8.56.
2-(Dicycloh exylp h osp h in o)a n isole (Liga n d 10). Ligand
10 was prepared from the sequential reaction of o-bromoani-
t
sole (1.00 gm, 5.35 mmol), BuLi (6.3 mL of 1.7 M solution in
hexane, 10.7 mmol), and dicylcohexylphosphinochloride (1.5
g, 6.2 mmol) (yield: 1.36 g, 84%) by the procedure described
for the preparation of ligand 7. 31P{1H} NMR (CDCl3): δ -9.6.
13C{1H} NMR (CDCl3): δ 162.7 (d, J PC ) 11), 134.8 (d, J PC
)
10), 129.8, 122.7 (d, J PC ) 21), 120.0 (d, J PC ) 4), 110.3, 55.1,
32.6 (d, J PC ) 12), 30.4 (d, J PC ) 17), 29.1 (d, J PC ) 8), 27.0
(m, 2C), 26.3. Anal. Calcd for C19H29OP: C, 74.97; H, 9.60; P,
10.18. Found: C, 74.98; H, 9.94; P, 10.02.
Com p lex 11. Methylene chloride (4 mL) was added to a
mixture of {Pd[P(o-toluyl)3](4-tBu-C6H4)(µ-Br)}2 (250 mg, 0.20
mmol) and ligand 1 (140 mg, 0.40 mml) at room temperature
under argon. The mixture was stirred for 4 h and concentrated
to ca. 0.5 mL. Heptane (20 mL) was added to the solution, and
the mixture was stirred for 30 min and filtered. The solid was
washed with heptane (4 × 5 mL) and dried under vacuum,
yielding compound 11 as a pale yellow solid (yield: 235 mg,
88%). Crystals of compound 11 suitable for X-ray crystal-
lographic diffraction were obtained from the solution of
CH2Cl2/heptane (volume ratio ) 1:32) at room temperature.
31P{1H} NMR (CDCl3): δ 16.3. 1H NMR (CDCl3): δ 7.8-7.0
(m, 12H, ArH), 6.65 (m, 6H, ArH), 4.70 (br, 1H, -OCH2), 4.21
(br, 1H, -OCH2), 3.85 (br s, 2H, -OCH2CH2O-), 2.15 (s, 3H,
-CH3), 1.14 (s, 9H, -C(CH3)3). 1H NMR (CDCl3, 55 °C): δ 7.81
(d/d, J ) 8.7/5.1, 2H, ArH), 7.50 (t, J ) 6.9, 2H, ArH), 7.46-
1
product (yield: 5.66 g, 90.7%). 31P{1H} (CDCl3): δ -18.5. H
NMR (CDCl3): δ 7.62 (br, 1H, ArH), 7.40 (br, 1H, ArH), 7.25
(m, 2H, ArH), 6.17 (d, J PH ) 6.5, 1H CH(OCH3)2), 3.35 (s, 6H,
-OCH3), 2.0-0.9 (m, 22H, CyH). 13C{1H} NMR (CDCl3): δ
144.8 (d, J PC ) 22), 134.3 (d, J PC ) 25), 132.3, 128.5, 127.5,
126.2 (d, J PC ) 5), 101.8 (d, J PC ) 29), 53.8, 34.2 (d, J PC ) 12),
30.3 (d, J PC ) 17), 29.3 (d, J PC ) 9), 27.0 (m, 2C), 26.2. Anal.
Calcd for C21H33O2P: C, 72.38; H, 9.55; P, 8.89. Found: C,
72.46; H, 9.90; P, 9.03.
o-Dicycloh exylp h osp h in o-N,N-d im et h ylb en zyla m in e
(Liga n d 8). P a r t I. A reaction mixture of ligand 7 (1.0 g, 2.9
mmol), deoxygenated water (5 mL), and p-toluenesulfonic acid
monohydrate (55 mg, 0.29 mmol) in THF (10 mL) was stirred
at 50-55 °C for 20 h. The reaction was cooled to ambient
temperature and extracted with diethyl ether (2 × 5 mL). The

(P,O)n-Palladium(II)Aryl(Br) Complexes
Organometallics, Vol. 18, No. 10, 1999 1851
7.10 (br m, 10H, ArH), 6.76 (d/d, J ) 8.4/3.6, 2H, ArH), 6.67
(d, J ) 8.4, 2H, ArH), 4.48 (br, 2H, -OCH2CH2O-), 3.86 (m,
2H, -OCH2CH2O-), 2.20 (s, 3H, CH3), 1.19 (s, 9H, C(CH3)).
1H NMR (C6D5Cl, 30 °C): δ 4.5 (br, 1H, -OCH2-), 3.6 (br,
1H, -OCH2-, partially overlapped), 3.31 (br, 2H, -OCH2-
CH2-, partially overlapped). 1H NMR (C6D5Cl, 70 °C): δ 4.01
(br s, 2H, -OCH2CH2-), 3.32 (br m, 2H, -OCH2CH2-). 13C-
{1H} NMR (CDCl3): δ 147.1(d, J PC ) 13), 145.4, 136.6, 135.6,
134.7 (d, J PC ) 4.7), 133.6 (br, 2C), 131.4, 130.5 (br), 128.6
(br, 2C), 126.8, 126.3 (d, J PC ) 8), 124.4, 109.3 (-OCO-), 67.3
(br, -OCH2-), 64.8 (br, -OCH2-), 33.8, 31.5, 30.4. Anal. Calcd
for C32H34BrO2PPd: C, 57.54; H, 5.13; P, 4.64. Found: C, 58.25;
H, 5.13; P, 4.45.
(11 mg, 19 µmol), and ligand 1 (15 mg, 40 µmol) in toluene (4
mL) was heated at 105 °C for 90 min. The reaction was cooled
to room temperature, taken up in diethyl ether (125 mL),
washed with water (2 × 30 mL) and brine (30 mL), dried over
MgSO4, filtered, and concentrated under vacuum. The crude
product was purified by column chromatography on silica gel
using hexane (or hexanes/ethyl acetate) as the eluent to afford
compound 14 (315 mg, 83% yield), after drying under vacuum,
1
as a pale yellow solid. H NMR (CDCl3): δ 7.34-7.24 (m, 7H,
ArH), 6.75 (d, 2H, J ) 8.8 Hz, ArH), 4.51 (s, 2H, N-CH2-Ar),
3.01 (s, 3H, N-CH3), 1.31 (s, 9H, C(CH3)3). 13C{1H} NMR
(CDCl3): δ 147.6, 139.4, 128.5, 128.2, 126.8, 126.8, 125.9, 112.2,
57.0, 38.5, 33.7, 31.5. Anal. Calcd for C18H23N: C, 85.32; H,
9.15; N, 5.53. Found: C, 85.67; H, 9.77; N, 5.34.
Com p lex 12. Methylene chloride (1.5 mL) was added to a
mixture of {Pd[P(o-toluyl)3](4-tBu-C6H4)(µ-Br)}2 (150 mg, 0.12
mmol) and ligand 6 (120 mg, 0.33 mmol) at room temperature
under argon. The mixture was stirred for 3 h and filtered. The
filtrate was concentrated to ca. 1 mL under vacuum and
layered with heptane (16 mL), and the mixture was kept at
room temperature for 12 h. Crystals of 12 suitable for X-ray
analysis were obtained. 31P{1H} NMR (CDCl3): δ 28.5. 1H
NMR (CDCl3): δ 7.70 (d/d/d, J ) 7.8/4.2/1.5, 1H, ArH), 7.59
(t, J ) 7.8, 1H, ArH), 7.47 (t, J ) 7.7, 1H, ArH), 7.37 (t, J )
7.7, 1H, ArH), 7.18 (br d, 2H, ArH), 6.98 (d, J ) 7.8, 2H, ArH),
4.71 (q, J ) 7.1, 1H, -OCH2-), 4.12 (m, 1H, -OCH2-), 3.81
(m, 1H, -OCH2-), 3.71 (m, 1H, -OCH2-), 2.30 (s, 3H, CH3),
1.23 (9H, C(CH3)3). The 22 hydrogens of the two Cy groups
Com p ou n d 15 (en tr y B, Ta ble 2). Compound 15 (437 mg,
98% yield) was obtained as a pale yellow solid from the
reaction of 4-bromobenzophenone (440 mg, 1.69 mmol), pip-
eridine (0.20 mL, 2.0 mmol), NaOtBu (192 mg, 2.00 mmol),
Pd(dba)2 (19 mg, 33 µmol), and ligand 1 (32 mg, 90 µmol) in
toluene (4 mL) at 105 °C for 60 min. The isolated sample
contained trace amount of hexanes. 1H NMR (CDCl3): δ 7.90-
7.70 (m, 4H, ArH), 7.51-7.27 (m, 3H, ArH), 6.86 (m, 2H, ArH),
3.36 (br, 4H, -CH2-N-CH2-), 1.65 (br s, 6H, N-C-CH2-
CH2-CH2-). 13C{1H} NMR (CDCl3): δ 195.0, 154.1, 139.0,
132.6, 131.2, 129.4, 128.2, 128.0, 113.1, 48.6, 25.3, 24.3. Anal.
Calcd for C18H19NO: C, 81.47; H, 7.22; N, 5.28. Found: C,
81.74; H, 7.58; N, 4.99.
Com p ou n d 16 (en tr y C, Ta ble 2). Compound 16 (518 mg,
93% yield) was obtained as a colorless oil from the reaction of
4-bromo-tert-butylbenzene (319 mg, 1.50 mmol), dioctylamine
(0.54 mL, 1.80 mmol), NaOtBu (173 mg, 1.80 mmol), Pd(dba)2
(8.0 mg, 14 µmol), and ligand 1 (15 mg, 43 µmol) in toluene (4
mL) at 105 °C for 7 h. 1H NMR (CDCl3): δ 7.30 (d, 2H, J )
9.0 Hz, ArH), 6.66 (d, 2H, J ) 9.0 Hz, ArH), 3.28 (br t, 4H, J
) 8.0 Hz, CH2-N-CH2), 1.63 (br, 4H), 1.43-1.36 (br, 29H),
0.95 (br, 6H, 2 CH3’s). 13C{1H} NMR (CDCl3): δ 146.5, 138.0,
126.4, 111.7, 51.6, 34.1, 32.3, 32.0, 29.9, 29.8, 27.8, 27.7, 23.1,
14.6. Anal. Calcd for C26H47N: C, 83.57; H, 12.68; N, 3.75.
Found: C, 83.44; H, 12.39; N, 3.71.
Com p ou n d 17 (en tr y D, Ta ble 2). Compound 17 (299 mg,
91% yield) was obtained as a colorless oil from the reaction of
5-bromo-m-xylene (272 mg, 1.47 mmol), N-methylbenzylamine
(214 mg, 1.77 mmol), NaOtBu (170 mg, 1.77 mmol), Pd(dba)2
(17 mg, 30 µmol), and ligand 1 (28 mg, 80 µmol) in toluene (4
mL) at 105 °C for 2 h. Alternatively, this compound (278 mg,
83% yield) was obtained as a colorless oil from the reaction of
5-iodo-m-xylene (343 mg, 1.50 mmol), N-methylbenzylamine
(214 mg, 1.77 mmol), NaOtBu (170 mg, 1.77 mmol), Pd(dba)2
(17 mg, 30 µmol), and ligand 1 (28 mg, 80 µmol) in 1,4-dioxane
(4 mL) at 105 °C for 3.5 h (entry E, Table 1). 1H NMR
(CDCl3): δ 7.37-7.29 (m, 5H, ArH), 6.47 (br, 3H, ArH), 4.56
(s, 2H, N-CH2-Ar), 3.02 (s, 3H, N-CH3), 2.32 (s, 6H, Ar-
(CH3)2). 13C{1H} NMR (CDCl3): δ 150.0, 139.2, 138.7, 128.5,
126.8, 126.7, 118.7, 110.3, 56.6, 38.3, 21.7. Anal. Calcd for
1
show broad multiple resonances in the range 1.9-0 ppm. H
NMR (toluene-d8, 23 °C): δ 4.83 (q, J ) 7.1, 1H, -OCH2-),
3.54 (m, 1H, -OCH2-), 3.42 (m, 1H, -OCH2-), 3.15 (m, 1H,
-OCH2-). 1H NMR (toluene-d8, 105 °C): δ 4.7-3.8 (br, 2H,
-OCH2CH2O-), 3.39 (br, 2H, -OCH2CH2O-). 13C{1H} NMR
(CDCl3): δ 148.7 (d, J PC ) 10), 145.8, 135.4, 134.0, 133.1, 130.8,
127.8 (d, J PC ) 5), 126.3 (d, J PC ) 7), 124.7 (d, J ) 27), 124.3
(br), 109.5 (OCO), 67.2 (-OCH2-), 64.5 (-OCH2-), 37.3 (d,
J PC ) 23), 35.5 (d, J PC ) 24), 33.9, 31.6, 31.5, 30.1 (d, J PC ) 4),
29.2, 27.5-26.7 (overlapping signals), 26.0, 25.5.
Com p lex 13. Methylene chloride (4 mL) was added to a
mixture of {Pd[P(o-toluyl)3](4-tBu-C6H4)(µ-Br)}2 (187 mg, 0.150
mmol) and ligand 2 (201 mg, 0.600 mmol) at room temperature
under argon. The mixture was stirred for 4 h and filtered, and
the filtrate was concentrated to ca. 0.5 mL under vacuum.
Pentane (20 mL) was added to the concentrated solution, and
the mixture was stirred for 30 min and then filtered. The
solid was washed with pentane (4 × 5 mL) and dried under
vacuum, yielding compound 13 as a pale yellow solid (yield:
285 mg, 87%). Crystals of compound 13 suitable for X-ray
crystallographic diffraction were obtained from the solution
of CH2Cl2/heptane (volume ratio ) 1:32) at room temperature.
1
31P{1H} NMR (CDCl3): δ18.0. H NMR (CDCl3): δ 7.82 (d, J
) 6.9, 2H, ArH), 7.44 (t, J ) 7.5, 2H, ArH), 7.40-7.10 (m, 24H,
ArH), 6.91 (m, 2H, ArH), 6.73 (d, J ) 8.1, 2H, ArH), 6.52 (d,
J ) 7.8, 2H, CH), 4.08 (m, 4H, OCH2CH2O), 3.92 (m, 4H,
OCH2CH2O), 1.16 (s, 9H, CMe3). 13C{1H} NMR (CDCl3): δ
147.1, 145.5, 141.3, 136.2, 135.6 (2C), 133.3, 131.5, 130.2,
129.4, 128.5, 127.5 (2C), 125.1, 102.2, 65.4, 33.8, 31.7. Anal.
Calcd for C52H51BrO4P2Pd: C, 63.20; H, 5.20; P, 6.27. Found:
C, 63.57; H, 5.67; P, 6.03.
P r oced u r e for P d (d ba )2/Liga n d 1-5-Ca ta lyzed Rea c-
tion s of 4-Br om obip h en yl w ith Mor p h olin e a n d Dibu -
tyla m in e. A mixture of 4-bromobiphenyl (233 mg, 1.00 mmol),
morpholine (0.10 mL, 1.1 mmol) or dibutylamine (0.19 mL,
1.1 mmol), NaOtBu (116 mg, 1.20 mmol), Pd(dba)2 (12 mg, 20
µmol), and ligands 1-5 (60 µmol) in toluene (4 mL) was heated
at 105 °C for 75 min (morpholine substrate) or for 90 min (di-
n-butylamine substrate). At the end of the reaction period the
reactions were analyzed by GC-MS. Results are shown in
Table 1.
C
16H19N: C, 85.28; H, 8.50; N, 6.22. Found: C, 85.32; H, 8.42;
N, 5.98.
Com p ou n d 18 (en tr y F , Ta ble 2). Compound 18 (272 mg,
88% yield) was obtained as a yellow oil from the reaction of
4-cyanobromobenzene (238 mg, 1.31 mmol), 2,4,6-trimethyl-
aniline (212 mg, 1.56 mmol), NaOtBu (151 mg, 1.57 mmol),
Pd(dba)2 (15 mg, 26 µmol), and ligand 1 (25 mg, 72 µmol) in
toluene (4 mL) at 105 °C for 2 h. A trace amount of diarylated
product is generated in this reaction. The amount of diarylated
product formed is greater if less than 1.2 equiv of 2,4,6-
trimethylaniline is used. 1H NMR (CDCl3): δ 7.37 (d, 2H, J )
8.8, ArH), 6.95 (s, 2H, ArH), 6.43 (d, 2H, J ) 8.8, ArH), 5.54
(br s, 1H, NH), 2.31 (s, 3H, CH3), 2.16 (6H, 2 CH3’s). Anal.
Calcd for C16H16N2: C, 81.32; H, 6.82; N, 11.85. Found: C,
80.92; H, 7.19; N, 11.63.
Com p ou n d 14 (en tr y A, Ta ble 2). A mixture of 4-bromo-
tert-butylbenzene (319 mg, 1.50 mmol), N-methylbenzylamine
(218 mg, 1.80 mmol), NaOtBu (173 mg, 1.80 mmol), Pd(dba)2
Com p ou n d 19 (en tr y G, Ta ble 2). Compound 19 (320 mg,
90% yield) was obtained as a colorless oil from the reaction of

1852 Organometallics, Vol. 18, No. 10, 1999
Bei et al.
4-ethoxybromobenzene (281 mg, 1.40 mmol), 2,4,6-trimethyl-
aniline (227 mg, 1.68 mmol), NaOtBu (161 mg, 1.68 mmol),
Pd(dba)2 (16 mg, 28 µmol), and ligand 1 (27 mg, 78 µmol) in
toluene (4 mL) at 105 °C for 21 h. 1H NMR (CDCl3): δ 6.91 (s,
2H, ArH), 6.72 (d, 2H, J ) 8.6, ArH), 6.44 (d, 2H, J ) 8.6,
ArH), 4.9 (br, 1H, NH), 3.94 (q, 2H, J ) 6.9, OCH2), 2.29 (s,
3H, ArCH3), 2.15 (s, 6H, 2 ArCH3’s), 1.36 (t, 3H, J ) 6.9, O-C-
CH3). 13C{1H} NMR (CDCl3): δ 151.8, 140.5, 136.5, 135.1,
134.6, 129.2, 115.5, 114.8, 63.9, 20.8, 18.2, 15.0. Anal. Calcd
for C17H21NO: C, 79.96; H, 8.29; N, 5.49. Found: C, 80.27; H,
8.48; N, 5.24.
113.6, 66.8, 49.4, 21.5. Anal. Calcd for C12H17NO: C, 75.35;
H, 8.96; N, 7.32. Found: C, 75.48; H, 9.23; N, 7.33.
Com p ou n d 24 (en tr y B, Ta ble 4). Compound 24 (289 mg,
96% yield) was obtained as a yellow oil from the reaction of
4-chlorobenzophenone (217 mg, 1.00 mmol), N-benzylmethyl-
amine (0.14 mL, 1.1 mmol), NaOtBu (125 mg, 1.30 mmol), Pd-
(dba)2 (12 mg, 21 µmol), and ligand 6 (22 mg, 61 µmol) in
1
toluene (4 mL) at 105 °C for 1 h. H NMR (CDCl3): δ 7.83 (d,
J ) 9.0, 2H, ArH), 7.75 (d, J ) 6.8, 2H, ArH), 7.58-7.22 (m,
8H, ArH), 6.77 (d, J ) 8.9, 2H, ArH), 4.69 (s, 2H, -N-CH2-
Ph), 3.19 (s, 3H, -NCH3). 13C{1H} NMR (CDCl3): δ 195.0,
152.7, 139.2, 137.5, 132.8, 131.1, 129.4, 128.8, 127.9, 127.2,
126.4, 125.3, 110.8, 56.0, 38.8. Anal. Calcd for C21H19NO: C,
83.69; H, 6.35; N, 4.65. Found: C, 83.38; H, 6.45; N, 4.46.
Com p ou n d 25 (en tr y C, Ta ble 4). Compound 25 (238 mg,
90% yield) was obtained as a colorless cotton-like solid from
the reaction of 4-chlorobenzonitrile (138 mg, 1.00 mmol),
N-phenylpiperazine (0.17 mL, 1.11 mmol), NaOtBu (125 mg,
1.30 mmol), Pd(dba)2 (12 mg, 21 µmol), and ligand 6 (22 mg,
61 µmol) in toluene (4 mL) at 105 °C for 1 h. Isolated compound
contained trace amounts of solvents. 1H NMR (CDCl3): δ 7.50
(d, J ) 8.8, 2H, ArH), 7.28 (m, 3H, ArH), 6.95 (d, J ) 8.3, 2H,
ArH), 6.89 (d, J ) 8.0, 2H, ArH), 3.48 (br, 4H, -NCH2’s), 3.31
(br, 4H, -NCH2’s). 13C{1H} NMR (CDCl3): δ 153.2, 150.7,
133.5, 129.3, 120.4, 119.9, 116.4, 114.3, 100.6, 49.0, 47.2. Anal.
Calcd for C17H17N3: C, 77.54; H, 6.51; N, 15.96. Found: C,
77.34; H, 6.43; N, 16.03.
Com p ou n d 26 (en tr y D, Ta ble 4). Compound 26 (311 mg,
97% yield) was obtained as a colorless oil from the reaction of
4-chlorobenzotrifluoride (0.13 mL, 0.97 mmol), dihexylamine
(0.25 mL, 1.1 mmol), NaOtBu (125 mg, 1.30 mmol), Pd(dba)2
(12 mg, 21 µmol), and ligand 6 (22 mg, 61 µmol) in toluene (4
mL) at 105 °C for 1 h. 1H NMR (CDCl3): δ 7.39 (d, J ) 8.8,
2H, ArH), 6.59 (d, J ) 8.8, 2H, ArH), 3.27 (t, J ) 7.6, 4H,
-NCH2’s), 1.55 (br, 4H, -CH2CH2’s), 1.31 (br, 12H), 0.90 (t, J
) 6.4, 6H, 2 CH3’s). 13C{1H} NMR (CDCl3): δ 150.1, 126.5,
110.5, 51.0, 31.7, 27.0, 26.8, 22.7, 14.0 (due to coupling to
fluorine atoms, the two carbon atoms R and â to fluorine atoms
could not be conclusively identified from the baseline). Anal.
Calcd for C19H30F3N: C, 69.27; H, 9.18; N, 4.25. Found: C,
69.22; H, 9.17; N, 4.42.
Com p ou n d 20 (en tr y H, Ta ble 2). Compound 20 (339 mg,
92% yield) was obtained as a colorless solid from the reaction
of 9-bromophenanthrene (352 mg, 1.37 mmol), aniline (153 mg,
1.64 mmol), NaOtBu (158 mg, 1.64 mmol), Pd(dba)2 (16 mg,
28 µmol), and ligand 1 (26 mg, 75 µmol) in toluene (4 mL) at
105 °C for 3 h. The isolated sample contained a trace amount
of solvents. 1H NMR (CDCl3): δ 8.74 (d, 1H, J ) 8.0, ArH),
8.64 (m, 1H, ArH), 8.13 (d, 1H, J ) 8.0, ArH), 7.73-7.54 (m,
6H, ArH), 7.34-7.24 (m, 2H, ArH), 7.06 (d, 2H, J ) 8.4, ArH),
6.98 (t, 1H, J ) 7.4, ArH), 5.95 (br, 1H, NH). 13C{1H} NMR
(CDCl3): δ 144.6, 136.9, 132.5, 131.4, 129.4, 128.1, 127.8, 127.5,
126.9, 126.8, 126.6, 125.0, 123.2, 122.4, 122.3, 120.7, 117.9,
114.7. Anal. Calcd for C20H15N: C, 89.19; H, 5.61; N, 5.20.
Found: C, 89.12; H, 5.82; N, 5.07.
Com p ou n d 21 (en tr y I-K, Ta ble 2). Compound 21 (381
mg, 96% yield) was obtained as a colorless solid from the reac-
tion of 2-(2′-bromophenyl)-2-methyl-1,3-dioxolane (318 mg,
1.31 mmol), 2-chloro-6-methylaniline (195 mg, 1.38 mmol),
NaOtBu (152 mg, 1.58 mmol), Pd(dba)2 (15 mg, 28 µmol), and
ligand 1 (18 mg, 52 µmol) in toluene (4 mL) at 105 °C for 2 h.
1H NMR (CDCl3): δ 7.51 (m, 2H, ArH and NH), 7.36 (d, 1H,
J ) 7.9, ArH), 7.19 (d, 1H, J ) 7.3, ArH), 7.13-7.06 (m, 2H,
ArH), 6.83 (t, 1H, J ) 7.3, ArH), 6.27 (d, 1H, J ) 7.9, ArH),
4.17 (m, 2H, O-CH-CH-O), 3.97 (m, 2H, O-CH-CH-O),
2.23 (s, 3H, CH3), 1.89 (s, 3H, CH3). 13C{1H} NMR (CDCl3): δ
142.4, 137.4, 136.8, 131.2, 129.3, 128.8, 127.5, 126.8, 126.4,
125.3, 118.5, 113.5, 109.6, 64.1, 24.1, 18.8. Anal. Calcd for
C
17H18ClNO2: C, 67.21; H, 5.97; N, 4.61. Found: C, 66.92; H,
5.83; N, 4.53.
Com p ou n d 22 (en tr y J , Ta ble 2). Compound 22 (439 mg,
97% yield) was obtained as a colorless oil from the reaction of
2-bromoanisole (300 mg, 1.60 mmol), 2,6-diisopropylaniline
(298 mg, 1.68 mmol), NaOtBu (161 mg, 1.68 mmol), Pd(dba)2
(18 mg, 31 µmol), and ligand 1 (30 mg, 86 µmol) in toluene (4
mL) at 105 °C for 1 h. 1H NMR (CDCl3): δ 7.41-7.21 (m, 3 H,
ArH), 6.94 (d, 1H, J ) 7.4, ArH), 6.83-6.73 (m, 2H, ArH), 6.23
(d, 1H, J ) 7.4, ArH), 5.72 (br, 1H, NH), 4.01 (s, 3H, OCH3),
3.28 (heptet, 2H, J ) 6.9, 2 CHMe2’s), 1.25 (d, 12H, J ) 6.9, 2
(-CH3)2’s). 13C{1H} NMR (CDCl3): δ 147.6, 146.2, 137.9, 135.4,
127.0, 123.7, 121.1, 116.7, 110.9, 109.7, 55.7, 28.1, 23.9. Anal.
Calcd for C19H25NO: C, 80.52; H, 8.89; N, 4.94. Found: C,
79.93; H, 8.89; N, 4.85.
Com p ou n d 27 (en tr y E, Ta ble 4). Compound 27 (277 mg,
89% yield) was obtained as a white crystalline solid from the
reaction of 2-(2′-chlorophenyl)-2-methyl-1,3-dioxolane (198 mg,
1.00 mmol), 2-tert-butylaniline (0.17 mL, 1.1 mmol), NaOtBu
(125 mg, 1.30 mmol), Pd(dba)2 (12 mg, 21 µmol), and ligand 6
1
(22 mg, 61 µmol) in toluene (4 mL) at 105 °C for 2 h. H NMR
(CDCl3): δ 7.47 (br t, J ) 6.6, 2H, ArH), 7.29 (d, J ) 6, 1H,
ArH, partially overlap), 7.28 (br, 1H, NH), 7.18-7.06 (m, 3H,
ArH), 6.90 (d, J ) 8.1, 1H, ArH), 6.79 (t, J ) 8.0, 1H, ArH),
4.12 (br, 2H, -OCH2CH2O-), 3.95 (br, 2H, -OCH2CH2O-),
1.82 (s, 3H, CH3), 1.47 (s, 9H, C(CH3)3). 13C{1H} NMR
(CDCl3): δ 143.5, 142.9, 141.1, 128.9, 127.7, 127.1, 126.7, 126.4,
125.5, 123.2, 118.2, 115.8, 109.5, 64.1, 34.1, 30.2, 24.9. Anal.
Calcd for C20H25NO2: C, 77.14; H, 8.09; N, 4.50. Found: C,
77.09; H, 8.29; N, 4.46.
P r oced u r e for P d (d ba )2/Liga n d 6-10-Ca ta lyzed Rea c-
tion s of 5-Ch lor o-m -xylen e w ith Mor p h olin e a n d N-
Hep tylm eth yla m in e. A mixture of 5-chloro-m-xylene (0.14
mL, 1.0 mmol), morpholine(0.10 mL, 1.1 mmol) or N-methyl-
heptylamine (0.19 mL, 1.1 mmol), NaOtBu (130 mg, 1.20
mmol), Pd(dba)2 (12 mg, 20 µmol), and ligands 6-10 (60 µmol)
in toluene (4 mL) was heated at 105 °C for 60 min. At the end
of the reaction period the reactions were analyzed by GC-
MS. Results are shown in Table 3.
Com p ou n d 28 (en tr y F , Ta ble 4). Compound 28 (222 mg,
96% yield) was obtained as an off-white solid from the reaction
of 2-chloro-p-xylene (0.13 mL, 0.97 mmol), 2,4,6-trimethyl-
aniline (0.14 mL, 0.99 mmol), NaOtBu (125 mg, 1.30 mmol),
Pd(dba)2 (12 mg, 21 µmol), and ligand 6 (22 mg, 61 µmol) in
1
toluene (4 mL) at 105 °C for 1 h. H NMR (CDCl3): δ 7.02 (d,
J ) 7.4, 1H, ArH), 6.97 (s, 2H, ArH), 6.52 (d, J ) 7.4, 1H,
ArH), 5.98 (s, 1H, ArH), 4.84 (br, 1H, -NH), 2.34 (s, 3H,
-CH3), 2.29 (s, 3H, -CH3), 2.17 (br, 9H, 3 CH3’s). 13C{1H}
NMR (CDCl3): δ 144.2, 136.6, 136.0, 135.5, 134.9, 130.0, 129.2,
119.1, 118.4, 112.1, 21.3, 20.9, 18.2, 17.2. Anal. Calcd for
C17H21N: C, 85.30; H, 8.84; N, 5.85. Found: C, 85.29; H, 9.07;
N, 5.75.
Com p ou n d 23 (en tr y A, Ta ble 4). Compound 23 (181 mg,
92% yield) was obtained as a yellow oil from the reaction of
5-chloro-m-xylene (0.14 mL, 1.0 mmol), morpholine (0.10 mL,
1.0 mmol), NaOtBu (125 mg, 1.30 mmol), Pd(dba)2 (12 mg, 21
µmol), and ligand 6 (22 mg, 61 µmol) in toluene (4 mL) at 105
1
°C for 1 h. H NMR (CDCl3): δ 6.60 (s, 3 H, ArH), 3.88 (t, J )
4.8, 4H, -O(CH2)2-), 3.17 (t, J ) 4.8, 4H, -N(CH2)2-), 2.34
Com p ou n d 29 (en tr y G, Ta ble 4). Compound 29 (209 mg,
92% yield) was obtained as a yellow oil from the reaction of
(s, 6H, CH3). 13C{1H} NMR (CDCl3): δ 151.3, 138.5, 121.8,

(P,O)n-Palladium(II)Aryl(Br) Complexes
Organometallics, Vol. 18, No. 10, 1999 1853
2-chloro-p-xylene (0.13 mL, 0.97 mmol), octylamine (0.18 mL,
1.1 mmol), NaOtBu (125 mg, 1.30 mmol), Pd(dba)2 (12 mg, 21
µmol), and ligand 6 (22 mg, 61 µmol) in toluene (4 mL) at 105
°C for 3 h. 1H NMR (CDCl3): δ 6.97 (d, J ) 7.3, 1H, ArH),
6.50 (d, J ) 7.3, 1H, ArH), 6.48 (br, 1H, ArH), 3.44 (br, 1H,
-NH), 3.18 (t, J ) 7.2, 2H, -NCH2-), 2.35 (s, 3H, Ar-CH3),
2.13 (s, 3H, Ar-CH3), 1.69 (m, 2H, -NCH2CH2-), 1.6-1.2 (br,
10H, overlapped signals), 0.94 (br, 3H, CH2CH3). 13C{1H} NMR
(CDCl3): δ 146.0, 136.6, 129.8, 118.6, 117.2, 110.5, 43.9, 31.8,
29.6, 29.4, 29.3, 27.2, 22.6, 21.5, 16.9, 14.1. Anal. Calcd for
ArH), 7.00 (d, J ) 8.9, 2H, ArH), 6.94 (t, J ) 6.6, 1H, ArH),
6.81 (d, J ) 8.4, 1H, ArH), 6.76 (d, J ) 2.4, 1H, ArH), 6.61
(d/d, J ) 8.1/2.4, 1H, ArH), 5.98 (s, 2H, -OCH2O-), 5.57 (br
s, 1H, NH). 13C NMR (CDCl3): δ 148.1, 144.5, 142.7, 137.2,
129.2, 119.9, 116.1, 112.8, 108.4, 102.4, 100.9.
X-r a y Cr ysta llogr a p h y. Crystals were sealed in glass
capillaries and then optically aligned on the goniostat of a
Siemens P4 X-ray diffractometer. The reflections that were
used for the unit cell determination were located and in-
dexed by the automatic peak search routine provided with
XSCANS.36 The intensities of three standard reflections, which
were measured after every 100 reflections, showed no indica-
tion of crystal decomposition or sample movement for all of
these samples. The raw data were collected for Lorentz-
polarization effects. Initial coordinates for the non-hydrogen
atoms were determined by a combination of direct methods
(for 11, 13) or heavy atom method (for 12) and difference
Fourier calculations performed with the algorithms provided
in SHELXTL-IRIS operating on a Silicon Graphics Indigo
workstation. The hydrogen atom positions were idealized with
isotropic temperature factors at 1.2 times that of the adjacent
carbon. The positions of methyl hydrogens were optimized by
a rigid rotating group refinement with idealized tetrahedral
angles. For 11, there are three independent molecules (mol-
ecules 1-3) in the crystallographic asymmetric unit. For 12,
the crystallographic asymmetric unit also contained a molecule
of methylene chloride, which was located in a general position
within the unit cell. The tert-butyl substituent of 12 was
refined using a two-site staggered disorder (70:30) of the three
methyl carbons. The C-C bond lengths within the tert-butyl
group were restrained at 1.54 ( 0.02 Å. For 13, the crystal-
lographic asymmetric unit contained a heptane molecule
located in a general position. The individual positions of the
carbon atoms within the heptane molecule were refined by
restraining the C-C bond lengths to 1.54 ( 0.02 Å and the
nonbonding distances between alternate carbons to 2.52 ( 0.02
Å. Crystal data and refinement parameters are summarized
in Table 5. Further details of the crystallographic information
are provided in the Supporting Information.
C
16H27N: C, 82.34; H, 11.66; N, 6.00. Found: C, 82.23; H,
11.84; N, 5.91.
Com p ou n d 30 (en tr y H, Ta ble 4). Compound 30 (183 mg,
83% yield) was obtained as a yellow oil from the reaction of
2-chloroanisole (0.12 mL, 0.94 mmol), octylamine (0.19 mL,
1.1 mmol), NaOtBu (125 mg, 1.30 mmol), Pd(dba)2 (12 mg, 21
µmol), and ligand 6 (22 mg, 61 µmol) in toluene (4 mL) at 105
°C for 3 h. 1H NMR (CDCl3): δ 6.92 (t, J ) 7.6, 1H, ArH), 6.81
(d, J ) 7.6, 1H, ArH), 6.71 (d, J ) 7.6, 1H, ArH), 6.67 (t, J )
7.6, 1H, ArH), 4.22 (br, 1H, -NH), 3.86 (s, 3H, -OCH3), 3.16
(t, J ) 7.2, 2H, -NCH2-), 1.69 (pentet, 2H, -NCH2CH2CH2-
), 1.35 (br, 10H, 5 -CH2-’s), 0.95 (br, 3H, CH3). 13C{1H} NMR
(CDCl3): δ 146.7, 138.5, 121.3, 115.9, 109.7, 109.3, 55.3, 43.7,
31.8, 29.5, 29.4, 29.2, 27.2, 22.6, 14.0. Anal. Calcd for C15H25
-
NO: C, 76.55; H, 10.71; N, 5.95. Found: C, 76.74; H, 10.98;
N, 5.94.
Com p ou n d 31 (en tr y I, Ta ble 4). A mixture of 5-chloro-
m-xylene (0.14 mL, 1.04 mmol), N-heptylmethylamine (0.19
mL, 1.13 mmol), NaOtBu (125 mg, 1.30 mmol), Pd(dba)2 (12
mg, 21 µmol), and ligand 6 (22 mg, 61 µmol) in toluene (4 mL)
was heated to 105 °C for 1 h and analyzed by GC-MS. The
reaction was cooled to room temperature, taken up in diethyl
ether (125 mL), washed with water (30 mL) and brine (30 mL),
dried over MgSO4, filtered, and concentrated in vacuo. The
crude product was purified by column chromatography on
silica gel using hexanes as the eluent to afford compound 31,
after drying under vacuum, as a colorless oil (yield: 230 mg,
95%). Analogous reactions of 5-bromo-m-xylene (1 h, entry J ,
Table 4) and 5-iodo-m-xylene (15 min, entry K, Table 4) also
afford the desired 5-(N-heptylmethylamino)-m-xylene in 93%
and 91% isolated yields, respectively. 1H NMR (CDCl3): δ 6.33
(br, 3H, ArH), 3.25 (t, J ) 7.6, 2H, -NCH2-), 2.89 (s, 3H, -N-
CH3), 2.27 (s, 6H, Ar(CH3)2), 1.54 (br, 2H, -NCH2CH2-), 1.30
(br, 8H, -(CH2)4CH3), 0.89 (br t, J ) 6.6, 3H, -CH3). 13C{1H}
NMR (CDCl3): δ 149.6, 138.6, 117.9, 110.1, 52.8, 38.3, 31.9,
29.2, 27.1, 26.7, 22.6, 21.8, 14.1. Anal. Calcd for C16H27N: C,
82.34; H, 11.66; N, 6.00. Found: C, 82.02; H, 11.92; N, 6.21.
Com p ou n d 32 (en tr y L, Ta ble 4). Compound 32 (210 mg,
96% yield) was obtained as a yellow oil from the reaction of
5-chloro-1,3-benzodioxole (0.12 mL, 1.03 mmol), aniline (0.12
mL, 1.23 mmol), NaOtBu (130 mg, 1.35 mmol), Pd(dba)2 (12
mg, 21 µmol), and ligand 6 (15 mg, 42 µmol) in toluene (4 mL)
at 105 °C for 3 h. 1H NMR (CDCl3): δ 7.28 (t, J ) 7.9, 2H,
Ack n ow led gm en t. We thank Drs. Damodara M.
Poojary and Peter Desrosiers for insightful discussions.
Su p p or tin g In for m a tion Ava ila ble: Tables of final
positional parameters and isotropic and anisotropic displace-
ment parameters for all atoms and bond lengths and angles
for complexes 11-13. This material is available free of charge
via the Internet at http://pubs.acs.org.
OM9900162
(36) XSCANS (version 2.0) is
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