Oxidative Addition of Aryl Sulfonates to Palladium (0) Complexes of Mono- and Bidentate Phosphines. Mild Addition of Aryl Tosylates and the Effects of Anions on Rate and Mechanism

Article abstract of DOI:10.1021/om034187p

An analysis of the oxidative additions of aryl triflates to palladium(O) complexes of hindered mono and bis(phosphines) and aryl tosylates to palladium(O) complexes of bis(phosphines) are discussed. In the presence added halides reaction of Pd[P(o-tolyl)<

Full text of DOI:10.1021/om034187p

194
Organometallics 2004, 23, 194-202
Oxid a tive Ad d ition of Ar yl Su lfon a tes to P a lla d iu m (0)
Com p lexes of Mon o- a n d Bid en ta te P h osp h in es. Mild
Ad d ition of Ar yl Tosyla tes a n d th e Effects of An ion s on
Ra te a n d Mech a n ism
Amy H. Roy and J ohn F. Hartwig*
Department of Chemistry, Yale University, P.O. Box 208107,
New Haven, Connecticut 06520-8107
Received September 23, 2003
Oxidative additions of aryl halides to palladium complexes have been studied extensively
in recent years, but studies on the oxidative addition of aryl sulfonates to palladium
complexes are less common. Here, oxidative additions of aryl triflates to palladium(0)
complexes of hindered mono- and bis(phosphines) and the rare oxidative addition of aryl
tosylates to palladium(0) complexes of hindered bis(phosphines) are reported. Pd[P(o-tolyl)3]2
reacted with PhOTf in the presence of added halide salts to produce the corresponding
{Pd[P(o-tolyl)3](Ar)(µ-X)}2 complexes (X ) halide). The rate of oxidative addition was
accelerated by the addition of coordinating anions but was not affected by the addition of
weakly coordinating anions. This result suggests that the oxidative addition of aryl triflates
occurs to an anionic palladium complex ligated by halide. The addition of phenyl triflate to
Pd(PPF-t-Bu)[P(o-tolyl)3] in the presence of added bromide produced [(PPF-t-Bu)Pd(Ph)-
(Br)]. The rate of this oxidative addition was accelerated by added bromide but was more
greatly accelerated by the addition of PF6-, a typically noncoordinating anion. This result
indicates that a medium effect, not coordination of bromide prior to oxidative addition,
accounts for the acceleration of the rate of addition of aryl triflates to Pd(PPF-t-Bu)[P(o-
tolyl)3]. The oxidative addition of phenyl tosylate to Pd(PPF-t-Bu)[P(o-tolyl)3] and to Pd-
(CyPF-t-Bu)[P(o-tolyl)3] also occurred at room temperature to produce the corresponding
phenylpalladium tosylate complexes. In the presence of added bromide, arylpalladium
bromide complexes were formed. Like the addition of phenyl triflate to Pd(PPF-t-Bu)[P(o-
tolyl)3], the rate of oxidative addition was accelerated by addition of either strongly or weakly
coordinating anions. The additions of aryl tosylates were also faster in more polar solvents.
Thus, the effect of halide on the rate of addition of aryl tosylates to Pd(PPF-t-Bu)[P(o-tolyl)3]
is also more likely to result from a medium effect, rather than from coordination of anion to
palladium prior to oxidative addition.
In tr od u ction
products from the oxidative addition of aryl triflates
tend to be unstable, and few have been isolated.12-14
This product instability has restricted studies on the
oxidative addition of aryl triflates to palladium(0).
J utand and Mosleh reported the oxidative addition of
The oxidative addition of aryl halides and sulfonates
to palladium(0) is a fundamental organometallic trans-
formation.1 Many studies have been conducted on the
oxidative addition of aryl halides to palladium(0)
complexes,2-11 but fewer studies have been conducted
on the oxidative addition of aryl sulfonates.9,11,12 The
aryl triflates to Pd(PPh3)4 in the absence of added halide
+ 12
ions to form σ-ArPd(PPh3)2
.
Addition of chloride
either before or after the oxidative addition resulted in
the formation of σ-ArPdCl(PPh3)2. J utand and Brown
reported the mechanism of oxidative addition of aryl
triflates to the zerovalent (DPPF)Pd(η2-methylacrylate)
in DMF.9 Alcazar-Roman and Hartwig studied the
mechanism of the oxidative addition of aryl triflates to
Pd(BINAP)2 in the presence of amine. They found the
oxidative addition to be rate-determining, and trapping
* To whom correspondence should be addressed. E-mail:
J ohn.Hartwig@yale.edu.
(1) Stille, J . K.; Lau, K. S. Y. Acc. Chem. Res. 1977, 10, 434.
(2) Amatore, C.; Pfluger, F. Organometallics 1990, 9, 2276.
(3) Amatore, C.; Azzabi, M.; J utand, A. J . Am. Chem. Soc. 1991,
113, 1670.
(4) Amatore, C.; J utand, A.; M’Barki, M. A. Organometallics 1992,
11, 3009.
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9531.
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(8) Amatore, C.; Broeker, G.; J utand, A.; Khalil, F. J . Am. Chem.
Soc. 1997, 119, 5176.
(9) J utand, A.; Hii, K. K. M.; Thornton-Pett, M.; Brown, J . M.
Organometallics 1999, 18, 5367.
(11) Alcazar-Roman, L. M.; Hartwig, J . F. Organometallics 2002,
21, 491.
(12) J utand, A.; Mosleh, A. Organometallics 1995, 14, 1810.
(13) Lugdwig, M.; Stromberg, S.; Svensson, M.; Akermark, B.
Organometallics 1999, 18, 970.
(10) Alcazar-Roman, L. M.; Hartwig, J . F.; Rheingold, A. L.; Liable-
Sands, L. M.; Guzei, I. A. J . Am. Chem. Soc. 2000, 112, 4618.
(14) Hii, K. K.; Caridge, T. D. W.; Brown, J . M. Angew. Chem., Int.
Ed. 1997, 36, 984.
10.1021/om034187p CCC: $27.50 © 2004 American Chemical Society
Publication on Web 12/11/2003

Addition of Aryl Sulfonates to Palladium(0) Complexes
Organometallics, Vol. 23, No. 2, 2004 195
Sch em e 1
of the arylpalladium triflate complex with amine rapidly
formed [Pd(BINAP)(Ph)(NH2octyl)](OTf).11
Added anions have been shown to influence the
mechanisms of oxidative addition of aryl halides and
triflates to palladium(0).5,15-18 This effect has been
mainly attributed to coordination of the halide to
palladium prior to oxidative addition. Several reports
by Amatore, J utand, and co-workers suggest that oxida-
tive addition of aryl triflates and iodides to Pd(PPh3)4
is accelerated by the addition of chloride ions due to the
formation of Pd(PPh3)2Cl- prior to oxidative addi-
tion.5,12,19 Scott and Stille studied the oxidative addition
of vinyl triflates to Pd(PPh3)4 in the presence of LiCl
and reported a mechanism that involves initial coordi-
nation of chloride to palladium and subsequent oxida-
tive addition to the resulting anionic palladium com-
plex.18 The role of added halide ions in the Stille reaction
with aryl triflates was examined by Espinet and co-
workers.20 Their studies revealed that added chloride
ions accelerated the rate of the overall reaction when
AsPh3 was used as ligand and oxidative addition was
the rate-determining step. In this case, oxidative addi-
tion appeared to be accelerated by coordination of halide
to the palladium(0) species. In contrast, added chloride
retarded the rate of the overall reaction when catalyzed
by PPh3 complexes of palladium and transmetalation
was the rate-determining step. Transmetalation of
ArPdClL2 is slower than that of [ArPd(PPh3)2]+, which
was proposed to form by oxidative addition in the
absence of chloride.
Although catalytic reactions of aryl chlorides with
complexes of hindered alkylphosphines have recently
been observed,33 most complexes with this type of ligand
do not add aryl tosylates that lack activating groups.34
Here the oxidative addition of aryl triflates and aryl
tosylates to palladium(0) at room temperature, followed
by trapping with halide to form arylpalladium(II) halide
complexes, is reported.35 The oxidative addition of aryl
tosylates to palladium(0) in the absence of added halide
formed arylpalladium tosylate complexes. The mecha-
nisms of these processes were studied in the presence
of added halide ions because of the ambiguous role of
halides in these reactions and the instability of the
product of addition of aryl triflate in the absence of
trapping agents.
Resu lts
The oxidative addition of aryl tosylates is particularly
rare because of the low reactivity of these substrates.
The reactivity of aryl halide and sulfonate electrophiles
toward palladium(0) typically follows the trend ArI >
ArBr ≈ ArOTf . ArOTs > ArCl.21,22 To our knowledge,
there are no previous examples of oxidative addition of
aryl tosylates to produce isolated arylmetal tosylate
complexes. Cross couplings of aryl tosylates with
nickel,22-24 iron,25,26 and copper27 catalysts have re-
quired high temperatures, activated aryl tosylates, or
high catalyst loadings. Previous palladium-catalyzed
couplings of aryl tosylates are rare and have required
activated substrates or elevated temperatures.24,28-32
Oxid a tive Ad d ition of Ar OTf to P a lla d iu m (0)
Com p lexes. The oxidative addition of aryl triflates to
Pd[P(o-tolyl)3]2 (1) was examined and is summarized in
Scheme 1. Reaction between Pd[P(o-tolyl)3]2 and aryl
triflates in toluene without additives produced free P(o-
tolyl)3 and palladium black. In contrast, reaction be-
tween phenyl triflate and palladium(0) in the presence
of N(octyl)4Br at room temperature produced {Pd[P(o-
tolyl)3](Ph)(µ-Br)}2 (2) in 99% yield, as determined by
NMR spectroscopy with an internal standard (Scheme
1). Reaction of the more hindered o-tolyl triflate at room
temperature also produced {Pd[P(o-tolyl)3](o-tolyl)(µ-
Br)}2 (3) in 99% yield by NMR spectroscopy. At 70 °C
the oxidative addition of o-tolyl triflate was faster than
at room temperature, but the yield of aryl bromide
complex 3 was only 83%. Reaction of o-tolyl triflate and
Pd[P(o-tolyl)3]2 in the presence of N(octyl)4Cl at room
temperature produced {Pd[P(o-tolyl)3](o-tolyl)(µ-Cl)}2 (4)
in 98% yield.
(15) Amatore, C.; J utand, A. J . Organomet. Chem. 1999, 573, 254.
(16) Amatore, C.; J utand, A. Acc. Chem. Res. 2000, 33, 314.
(17) J utand, A. Eur. J . Inorg. Chem. 2003, 2017.
(18) Scott, W. J .; Stille, J . K. J . Am. Chem. Soc. 1986, 108, 3033.
(19) Amatore, C.; Azzabi, M.; J utand, A. J . Am. Chem. Soc. 1991,
113, 8375.
(20) Casado, A. L.; Espinet, P.; Gallego, A. M. J . Am. Chem. Soc.
2000, 122, 11771.
(21) Collman, J . P.; Hegedus, L. S.; Norton, J . R.; Finke, R. G.
Principles and Applications of Organotransition Metal Chemistry, 2nd
ed.; University Science Books: Mill Valley, CA, 1987.
(22) Zim, D.; Lando, V. R.; Dupont, J .; Monteiro, A. L. Org. Lett.
2001, 3, 3049.
(23) Kobayashi, Y.; Mizojiri, R. Tetrahedron Lett. 1996, 37, 8531.
(24) Bolm, C.; Hildebrand, J . P.; Rudolph, J . Synthesis 2000, 7, 911.
(25) Furstner, A.; Leitner, A.; Mendez, M.; Krause, H. J . Am. Chem.
Soc. 2002, 124, 13856.
(26) Furstner, A.; Leitner, A. Angew. Chem., Int. Ed. 2002, 41, 609.
(27) Erdik, E.; Eroglu, F. Synth. React. Inorg. Met.-Org. Chem. 2000,
30, 955.
(28) Hamann, B. C.; Hartwig, J . F. J . Am. Chem. Soc. 1998, 120,
7369.
(29) Kawatsura, M.; Hartwig, J . F. J . Am. Chem. Soc. 1999, 121,
1473.
The reactivities of palladium(0) complexes of bulky,
electron-rich phosphines toward the oxidative addition
of aryl tosylates were also examined, but these reactions
occurred in lower yields than the reactions with Pd[P(o-
tolyl)3]2. For example, treatment of palladium(0) com-
36
plexes of ligands such as PCy2(t-Bu) and PCy(t-Bu)2
with phenyl or o-tolyl triflate in the absence of added
halide did not yield products from oxidative addition.
However, oxidative addition of aryl triflate to these
complexes did occur in the presence of added halide. The
steric properties of the ligand and of the aryl triflate
(30) Kubota, Y.; Nakada, S.; Sugi, Y. Synlett 1998, 183-185.
(31) Huang, X.; Anderson, K. W.; Zim, D.; J iang, L.; Klapars, A.;
Buchwald, S. L. J . Am. Chem. Soc. 2003, 125, 6653.
(32) Nguyen, H. N.; Huang, X.; Buchwald, S. L. J . Am. Chem. Soc.
2003, 125, 11818.
(33) Littke, A. F.; Fu, G. C. Angew. Chem., Int. Ed. 2002, 41, 4176.
(34) For exceptions, see refs 31 and 32.
(35) Roy, A. H.; Hartwig, J . F. J . Am. Chem. Soc. 2003, 125, 8704.
(36) Galardon, E.; Ramdeehul, S.; Brown, J . M.; Cowley, A.; Hii, K.
K.; J utand, A. Angew. Chem., Int. Ed. 2002, 41, 1760.

196 Organometallics, Vol. 23, No. 2, 2004
Roy and Hartwig
Sch em e 2
Sch em e 4
Sch em e 3
dictated the rate of reaction and the yield of oxidative
36
addition product. Reaction between Pd[PCy2(t-Bu)]2
and PhOTf in the presence of NBu4Br at 70 °C produced
Pd[PCy2(t-Bu)]2(Ph)(Br) in 98% yield, but reaction of the
larger o-tolyl triflate occurred in lower yield due to the
slower reaction rate and the presence of byproducts.
tosylate 10 was formed from 6 in 92% yield in less than
5 min. The same reaction in the presence of bromide
formed the bromide complex 8 in 94% yield in less than
5 min. However, reactions of the analogues of 5 contain-
ing J osiphos ligands that lack a tert-butyl group formed
the addition product in lower yields and with slower
rates. The reactions of phenyl tosylate with 5 and 6
constitute the first oxidative additions of aryl tosylates
to form isolated aryl complexes.
Complexes 7-10 were independently synthesized, as
summarized in Scheme 4. Bromide complexes 7 and 8
were formed by the reaction between {Pd[P(o-tolyl)3]-
(Ph)(Br)}2 and the appropriate RPF-t-Bu ligand (R )
Ph, Cy) in THF at room temperature. The reactions
were complete within 20 min; the rates were limited by
the solubility of the palladium(II) dimer. Reaction of 7
and 8 with AgOTs in C6H6 produced arylpalladium
tosylate complexes 9 and 10 within minutes at room
temperature.
36
Reaction between the bulkier Pd[PCy(t-Bu)2]2 and
PhOTf was very slow at 70 °C in the presence of added
bromide and occurred in low yield. Significant amounts
of side products formed.
Palladium(0) complexes of sterically hindered versions
of the J osiphos ligands underwent addition of phenyl
triflate in the presence of added halide ions under mild
conditions, as illustrated in Scheme 2.37 Reaction be-
tween Pd[P(o-tolyl)3]2 and PPF-t-Bu or CyPF-t-Bu at
room temperature formed Pd(PPF-t-Bu)[P(o-tolyl)3] (5)
or Pd(CyPF-t-Bu)[P(o-tolyl)3] (6; Scheme 2). Subsequent
treatment of 5 or 6 with PhOTf in the presence of
N(octyl)4Br produced the corresponding phenylpalla-
dium bromide complexes 7 and 8 in 93% and 83% yields
in less than 5 min at room temperature.
Oxid a t ive Ad d it ion of Ar OTs t o P a lla d iu m (0)
Com p lexes. Reaction between Pd[P(o-tolyl)3]2 and
PhOTs in the presence or absence of halide did not
occur. However, palladium(0) complexes generated from
sterically hindered versions of the J osiphos ligands
underwent oxidative addition of phenyl tosylate under
mild conditions.37 Treatment of the PPF-t-Bu complex
5 with PhOTs produced the phenylpalladium tosylate
complex 9 in 85% yield (Scheme 3) after 16 h at room
temperature. Reaction in the presence of NBu4Br formed
the phenylpalladium bromide complex 7 in 95% yield
after only 9 h. Reactions of phenyl tosylate with CyPF-
t-Bu complex 6 were even faster. Phenylpalladium
Crystals of both 7 and 8 were obtained from a
concentrated toluene solution layered with pentane at
-35 °C. The structure of 7 is shown in Figure 1. Selected
bond distances and angles for 7 are provided in Table
1; other structural data are given in Table 4. The
geometry around palladium can be described as dis-
torted square planar. The Pd-P(2) bond is significantly
longer than the Pd-P(1) bond. This difference in Pd-P
distances can be attributed to the greater steric proper-
ties of the t-Bu groups on P(2) and to the stronger trans
influence38 of the phenyl group located trans to P(2),
relative to the halide located trans to P(1). Two isomeric
versions of complexes 7-10 could form, but only the
(37) Togni, A.; Breutel, C.; Schnyder, A.; Spindler, F.; Landert, H.;
Tijani, A. J . Am. Chem. Soc. 1994, 116, 4062.
(38) Appleton, T. G.; Clark, H. C.; Manzer, L. E. Coord. Chem. Rev.
1973, 10, 335.

Addition of Aryl Sulfonates to Palladium(0) Complexes
Organometallics, Vol. 23, No. 2, 2004 197
Ta ble 2. Selected In tr a m olecu la r Bon d Dista n ces
a n d An gles In volvin g th e Non -Hyd r ogen Atom s of
(CyP F -t-Bu )P d (P h )(Br ) (8)
Bond Distances (Å)
Pd(1)-P(1)
Pd(1)-Br(1)
2.2847(5)
2.5031(4)
Pd(1)-P(2)
Pd(1)-C(33)
2.4157(5)
2.0291(19)
Bond Angles (deg)
97.833(16) P(1)-Pd(1)-C(33) 88.27(5)
P(1)-Pd(1)-P(2) 98.045(19)
Br(1)-Pd(1)-P(2)
Br(1)-Pd(1)-C(33) 82.61(5)
F igu r e 1. ORTEP diagram of [Pd(PPF-t-Bu)(Ph)(Br)] (7)
with 30% ellipsoids.
Ta ble 1. Selected In tr a m olecu la r Bon d Dista n ces
a n d An gles In volvin g th e Non -Hyd r ogen Atom s of
(P P F -t-Bu )P d (P h )(Br ) (7)
Bond Distances (Å)
Pd(1)-P(1)
Pd(1)-Br(1)
2.240(1)
2.5301(6)
Pd(1)-P(2)
Pd(1)-C(1)
2.436(2)
2.045(6)
Bond Angles (deg)
Br(1)-Pd(1)-P(2)
Br(1)-Pd(1)-C(1)
98.97(4)
86.1(2)
P(1)-Pd(1)-C(1)
P(1)-Pd(1)-P(2)
83.8(2)
96.73(5)
F igu r e 3. Plots of kobs vs [ArOTf] and 1/kobs vs [P(o-tolyl)3]
for the oxidative addition of ArOTf to Pd[P(o-tolyl)3]2 in
benzene-d6 in the presence of NR4Br.
data are given in Table 4. Again, the geometry around
Pd can be described as distorted square planar. The Pd-
P(1) bond in 8 is slightly longer than the same bond in
complex 7, presumably because the steric demand of the
PCy2 group in 8 is larger than that of the PPh2 group
in 7.
Mech a n ism of th e Oxid a tive Ad d ition of Ar yl
Tr ifla tes to P a lla d iu m (0). Added anions have been
shown to influence the mechanisms of oxidative addition
of aryl halides and sulfonates to palladium(0). This
effect has been typically attributed to coordination of
the anion to palladium(0) prior to oxidative addi-
tion.3,5,12,18 Thus, we measured the kinetic order of
1
the various reaction components in eq 1 by H NMR
F igu r e 2. ORTEP diagram of [Pd(CyPF-t-Bu)(Ph)(Br)] (8)
with 30% ellipsoids.
product containing the palladium-bound phenyl group
cis to the smaller phosphine was observed by NMR
spectroscopy or X-ray diffraction.
The structure of 8 determined by X-ray diffraction is
shown in Figure 2. A high degree of positional disorder
in both the palladium complex and the cocrystallized
solvent was observed. Two alternative positions for the
unsubstituted Cp ring, C(6-10), and the phenyl ring,
C(33-38), were modeled and refined with anisotropic
displacement parameters. Selected bond distances and
angles for 8 are provided in Table 2; other structural
spectroscopy at 50 °C in C6D6 solvent in the presence
of added halide. The concentration of p-tolyl triflate was
varied from 0.022 to 0.18 M, the concentration of
N(octyl)4Br was varied from 0 to 0.12 M, and the
concentration of P(o-tolyl)3 was varied from 0.032 to
0.095 M. Excellent fits to a first-order decay of Pd[P(o-
tolyl)3]2 were obtained. Figure 3 shows the dependence
of kobs on the concentration of ArOTf and P(o-tolyl)3. The

198 Organometallics, Vol. 23, No. 2, 2004
Roy and Hartwig
Ta ble 4. Str u ctu r a l Da ta for Com p ou n d s 7 a n d 8a
7
8
empirical formula
C
42H53OP2Br-
FePd
C
47H77BrFe-
OP2Pd
formula wt
877.98
962.19
cryst dimens (mm3)
0.10 × 0.15 ×
0.35 × 0.20 ×
0.29
0.20
cryst syst
lattice params
a (Å)
b (Å)
c (Å)
monoclinic
orthorhombic
9.4928(2)Å
15.1888(5) Å
13.5344(4) Å
91.7135
1950.57(8)
P21 (No. 4)
2
1.495
900.00
19.74
22.412(5)
24.106(5)
16.388(3)
â (deg)
V (Å3)
8854(3)
C2221
8
1.444
4032
17.43
space group
Z
F igu r e 4. Plots of kobs vs [N(octyl)4Br] (circles) and kobs vs
[N(octyl)4Cl] (diamonds) for the oxidative addition of ArOTf
to Pd[P(o-tolyl)3]2 in benzene-d6 solvent in the presence of
added halide.
D
calc (g/cm3)
F000
µ(Mo KR) (cm-1
diffractometer
radiation
)
Nonius KappaCCD
Mo KR (λ ) 0.710 69 Å),
graphite monochromated
Ta ble 3. Dep en d en ce of t1/2 on [a n ion ] for th e
Oxid a tive Ad d ition of P h OTf to 5
temp
2θmax (deg)
no. of rflns measd
total
unique
structure soln
refinement
anomalous dispersion
no. of observns (I > 3.00σ(I)) 4363
no. of variables
rfln/param ratio
residuals: R; Rw
goodness of fit indicator
max peak in final
diff map (e/Å3)
-90.0 °C
183(2) K
56.56
[5] (M)
[N(octyl)4Br] (M)
[NBu4PF6] (M)
t1/2 (min)
61.2
0.023
0.023
0.023
0.024
0.093
0.026
0
0
23
11
10
13 797
10 177
0.075
5823 (Rint ) 0.061) 10 177
direct methods
full-matrix least squares
all non-hydrogen atoms
linear plot of kobs vs [ArOTf] in the presence of added
bromide indicated a first-order dependence of the rate
on [ArOTf]. The linear plot of 1/kobs vs [P(o-tolyl)3] for
reactions in the presence of added N(octyl)4Br indicated
that the reaction was inverse first order in P(o-tolyl)3.
Linear plots of kobs vs [N(octyl)4X] with a positive slope
and clear, nonzero y intercept were obtained from
reactions conducted in benzene-d6 with added bromide
and chloride, as shown in Figure 4. Reaction in the
absence of added bromide was slow; the value of t1/2 was
greater than 24 h. Thus, the observed nonzero y
intercept was not due to decomposition of the starting
material. Reactions in the presence of chloride ions were
2 times faster than those conducted in the presence of
added bromide ions. Reactions in the presence of the
combination of N(octyl)4Br and NBu4PF6 proceeded at
the same rate as those conducted with the same
concentration of added bromide and no added NBu4PF6.
These data indicate that the effect of added halogen on
the rate of oxidative addition of aryl triflates to Pd[P(o-
tolyl)3]2 does not simply result from a change in polarity
of the medium.
10 177
4811
21.16
0.0696, 0.1361
0.931
0.599
432
10.10
0.042; 0.041
1.37
0.70
min peak in final
-1.34
-0.732
diff map (e/Å3)
a
Full experimental details on the structure solution of com-
pounds 7 and 8 have been published previously.35
Mech a n ism of th e Oxid a tive Ad d ition of Ar yl
Tosyla tes to P d (P P F -t-Bu )[P (o-tolyl)3]. To determine
the kinetic order of the various components of the
oxidative addition of aryl tosylates to PPF-t-Bu com-
plexes of palladium(0) shown in eq 2, we measured the
rate behavior of the reaction by 31P NMR spectroscopy
at 55 °C in THF solvent in the presence and absence of
added bromide. The concentration of PhOTs was varied
The oxidative addition of phenyl triflate to Pd(PPF-
t-Bu)[P(o-tolyl)3] was performed in benzene-d6 solvent
in the presence of bromide ions and in the presence and
absence of NBu4PF6 ions to probe for a medium effect.
The rate of reaction between phenyl triflate and Pd-
(PPF-t-Bu)[P(o-tolyl)3] at -30 °C in the presence of 4
equiv of added bromide was faster than the rate of
reaction in the presence of only 1 equiv of added
bromide, as seen in Table 3. However, the reaction in
from 0.062 to 0.45 M, the concentration of N(octyl)4Br
was varied from 0 to 0.34 M, and the concentration of
P(o-tolyl)3 was varied from 0.088 to 0.26 M. Compound
5 was formed in situ from Pd[P(o-tolyl)3]2 and PPF-t-
Bu. Excellent fits to a first-order decay of 5 were
obtained. The plot of kobs vs [PhOTs] in Figure 5 in the
presence and absence of added bromide showed a first-
order dependence on this reagent. Linear plots of 1/kobs
vs [P(o-tolyl)3] from reactions in the presence and
absence of added N(octyl)4Br indicated that the reaction
is inverse first order in P(o-tolyl)3.
the presence of 4 equiv of added ions, consisting of a
-
mixture of 1 equiv of bromide and 3 equiv of PF6
,
occurred at the same rate as the reaction with 4 equiv
of bromide. These data indicate that the rate of reaction
is influenced by the polarity of the medium, not by
coordination of anion to palladium prior to oxidative
addition. The low solubility of 5 in DMF and NMP at
-30 °C limited our ability to obtain quantitative data
on the rate of oxidative addition of phenyl triflate to 5
in polar solvents.
Linear plots of kobs vs [NR4X] with a positive slope
and clear, nonzero y intercept were obtained from

Addition of Aryl Sulfonates to Palladium(0) Complexes
Organometallics, Vol. 23, No. 2, 2004 199
Sch em e 5
the addition of p-tolyl triflate to Pd[P(o-tolyl)3]2 are
shown in Scheme 5. Path A begins with direct oxidative
addition of aryl triflate to complex 1, followed by
dissociation of P(o-tolyl)3. In this mechanism, the added
halide would replace the coordinated triflate after
oxidative addition, and dimerization of this three-
coordinate monomer would form the final product. This
pathway predicts first-order behavior in aryl triflate and
zero-order behavior in both halide and P(o-tolyl)3. This
pathway is inconsistent with the observed positive order
in halide and the inverse order in P(o-tolyl)3.
F igu r e 5. Plots of kobs vs [PhOTs] and 1/kobs vs [P(o-tol)3]
for the oxidative addition of phenyl tosylate to complex 5.
Path B is initiated by dissociation of P(o-tolyl)3 from
1. Irreversible oxidative addition of aryl triflate and
subsequent rapid exchange of halide for triflate and
dimerization forms the final product. This pathway
predicts first-order behavior in aryl triflate, inverse-
order behavior in P(o-tolyl)3, and zero-order behavior in
added halide. These predictions are inconsistent with
the observed effects of anions. A positive order in added
halide was observed, and less coordinating anions such
-
as PF6 did not influence the rate of reaction.
Our data is more consistent with path C, which
involves initial associative or dissociative exchange of
halide for P(o-tolyl)3 and subsequent irreversible oxida-
tive addition of aryl triflate to the halide-ligated pal-
ladium species. This pathway predicts a reaction that
is first order in aryl triflate, inverse order in added P(o-
tolyl)3, and first order in added halide. Our kinetic data
are consistent with these predictions. In particular, this
pathway is consistent with the positive reaction order
in added halide and the absence of an effect of added
weakly coordinating anions, such as that in NBu4PF6.
The plot of kobs vs [X] (X ) Br, Cl) did contain a small
nonzero y intercept. This y intercept most likely corre-
sponds to the kobs value for reaction by path B.
Mech a n ism of th e Oxid a tive Ad d ition of Ar yl
Tosyla tes to P d (P P F -t-Bu )[P (o-tolyl)3]. Potential
mechanisms for the oxidative addition of PhOTs to
Pd(PPF-t-Bu)[P(o-tolyl)3] are shown in Scheme 6. Path
A begins with direct oxidative addition of aryl tosylate
to the 16-electron complex 5, followed by dissociation
of P(o-tolyl)3. In this mechanism the halogen would
replace the coordinated tosylate after oxidative addition.
This pathway predicts a first-order dependence on the
concentration of aryl tosylate and zero-order dependence
on the concentration of both bromide and P(o-tolyl)3.
This pathway is inconsistent with the observed inverse
order dependence on P(o-tolyl)3 and the positive order
in bromide.
F igu r e 6. Plots of kobs vs [additive] for the oxidative
addition of phenyl tosylate to 5. Additives: NBu4PF6
(triangles) and NBu4Br (diamonds).
reactions conducted with added bromide and PF6-, as
shown in Figure 6. The value of kobs for the reaction in
the absence of bromide ((4.1 ( 0.6) × 10-4 s-1) matched
the y intercept of the plot of kobs vs [N(octyl)4Br]
((3.9 ( 0.6) × 10-4 s-1) and of the plot of kobs vs [NBu4-
PF6] ((3.3 ( 0.7) × 10-4). The slope of the plot of kobs vs
[NBu4PF6] was roughly 4 times greater than that of the
plot of kobs vs [N(octyl)4Br]. Thus, reactions in the
presence of [NBu4PF6] were faster than those conducted
with added bromide.
Low solubility of the palladium(0) complex 5 in polar
solvents such as DMF and NMP limited our ability to
obtain quantitative data on solvent effects, but reactions
in these polar solvents were significantly faster than
reactions in less polar solvents. With 5 equiv of P(o-
tolyl)3 at 55 °C, reactions in DMF and NMP appeared
complete in 0.5 h instead of 3.5 h in C6H6 and THF.
Oxidative addition of PhOTs to 6 was complete within
5 min at 25 °C in THF, C6H6, or DMF.
Discu ssion
Mech a n ism of th e Oxid a tive Ad d ition of Ar yl
Tr ifla tes to P d [P (o-tolyl)3]2. Potential mechanisms for

200 Organometallics, Vol. 23, No. 2, 2004
Roy and Hartwig
Sch em e 6
oxidative addition of aryl sulfonates to complexes of
PPF-t-Bu was distinct from the role of anions in the
oxidative addition to complexes of P(o-tolyl)3. The effect
of anions on the oxidative addition of phenyl triflate to
the two palladium(0) complexes could result from a
medium effect or from direct coordination of anion prior
to oxidative addition. Our data indicate that the ac-
celeration of the oxidative addition to Pd[P(o-tolyl)3]2 by
added halide results from coordination of halide, while
the acceleration of the oxidative addition to Pd(PPF-t-
Bu)[P(o-tolyl)3] by added halide results from a medium
effect.
The different effect of halide on the reactions of the
two types of palladium(0) complexes in this study likely
results from a different effect of coordination on the
ability of the two palladium(0) species to undergo
oxidative addition. Coordination of an anion to a pal-
ladium(0) complex containing a hindered monophos-
phine, such as P(o-tolyl)3, would form a two-coordinate
anionic palladium complex after dissociation of phos-
phine, as shown in Path C of Scheme 5. In contrast,
coordination of halide to Pd(PPF-t-Bu)[P(o-tolyl)3] would
likely form the three-coordinate anionic [Pd(PPF-t-
Bu)X]- after dissociation of P(o-tolyl)3. Oxidative addi-
tion to two-coordinate palladium complexes is fast, but
oxidative addition to three-coordinate palladium com-
plexes is slow.2,40-42 Thus, the oxidative addition of aryl
triflates to Pd[P(o-tolyl)3]2 in the presence of added
halide can proceed through a mechanism involving
exchange of halide for one P(o-tolyl)3 to generate a two-
coordinate palladium(0) anion. Addition to this anionic
complex could be faster than addition to the neutral
complex because it may be more electron-rich. However,
oxidative addition of aryl triflates and tosylates to the
neutral two-coordinate Pd(PPF-t-Bu) is likely to occur
faster without coordination of bromide to generate a
three-coordinate complex, because addition to Y-shaped,
three-coordinate complexes is slow.2,41 The medium
effect observed in this case would then result from
increased polarization of the aryl sulfonate linkage
during the reaction or a reflection of the ionic character
of the palladium sulfonate product in the transition
state.
Path B is initiated by dissociation of P(o-tolyl)3 from
5, irreversible oxidative addition of aryl tosylate to the
unsaturated intermediate, and subsequent more rapid
exchange of bromide for tosylate to form 7 if bromide is
present. This pathway predicts a first-order dependence
on the concentration of aryl tosylate, inverse-order
dependence on the concentration of P(o-tolyl)3, and zero-
order dependence on the concentration of added bro-
mide. The kinetic orders in PhOTs and added P(o-tol)3
are consistent with reaction by path B in the absence
-
of added bromide or PF6
.
Path C involves initial associative or dissociative
exchange of bromide for P(o-tolyl)3 and subsequent
irreversible oxidative addition of aryl tosylate to the
anionic palladium(0). This pathway predicts a reaction
that is first order in aryl tosylate and inverse order in
P(o-tolyl)3. This pathway predicts that the reaction rate
will also be first order in bromide and that added NBu4-
PF6 would not strongly influence the rate of oxidative
-
addition because the PF6 would bind more weakly to
palladium. The strong effect of added NBu4PF6 argues
against reaction by path C.
Faster rates in the presence of more weakly coordi-
nating anions implies that the more polar medium
created by the added bromide and not direct coordina-
tion of this ion to palladium accounts for the faster rates.
The difference in observed rate constants for reactions
conducted with the different added anions presumably
results from differences in the degree or type of ion
Con clu sion s
The studies on the oxidative addition of aryl triflates
and tosylates reported here have several important
consequences. The oxidative addition of aryl triflates in
the presence of halide, combined with the reported
reductive elimination of aryl halide from arylpalladium
halide complexes,43 could lead to the development of a
stoichiometric or catalytic exchange of halide for triflates
or tosylates. In addition, the mild activation of aryl
tosylates may allow for cross-coupling reactions of aryl
tosylates under mild conditions. The rapid oxidative
addition step shows that the scope of the couplings of
aryl tosylates may be limited by transmetalation and
reductive elimination22 instead of oxidative addition. As
a result, aryl tosylates could replace the more expensive
pairing of ammonium PF6 and Br- salts in the non-
-
polar arene solvents. Consistent with the proposed
acceleration of the reactions from increasing the polarity
of the medium, reactions in more polar solvents in the
absence of added halogen occurred faster than those in
the arene solvents. This large acceleration of oxidative
addition of an aryl electrophile to palladium(0) in more
polar solvents39 is unusual.2,10,11,40
Com p a r ison of th e Effect of An ion s on th e
Rea ction s of Ar yl Su lfon a tes w ith P a lla d iu m (0)
Com p lexes Con ta in in g Hin d er ed Mon od en ta te
a n d Bid en ta te Liga n d s. The role of anions in the
(39) Sorensen, H. S.; Larsen, J .; Rasmussen, B. S.; Laursen, B.;
Hansen, S. G.; Skrydstrup, T.; Amatore, C.; J utand, A. Organometallics
2002, 21, 5243.
(40) Amatore, C.; J utand, A.; Khalil, F.; M’Barki, M. A.; Mottier, L.
Organometallics 1993, 12, 3168.
(41) Fauvarque, J .-F.; Pfluger, F.; Troupel, M. J . Organomet. Chem.
1981, 208, 419.
(42) Amatore, C.; J utand, A. Coord. Chem. Rev. 1998, 178-180, 511.
(43) Roy, A. H.; Hartwig, J . F. J . Am. Chem. Soc. 2001, 1232.

Addition of Aryl Sulfonates to Palladium(0) Complexes
Organometallics, Vol. 23, No. 2, 2004 201
5.7, 3.1 Hz), 38.17 (s at 25 °C, d with J ) 1.8 Hz at -80 °C)
38.86, 67.92 (d, J ) 7.0 Hz), 70.20 (d, J ) 7.8 Hz), 70.42, 75.28
(d, J ) 4.7 Hz), 78.00 (dd, J ) 41.1, 8.7 Hz), 95.61 (dd, J )
18.2, 6.3 Hz), 121.07, 124.51 (d, J ) 7.5 Hz), 127.38 (d, J )
12.1 Hz), 127.65 (d, J ) 7.0 Hz), 128.57 (d, J ) 11.6 Hz), 128.74
(d, J ) 1.3 Hz), 131.33 (d, J ) 2.0 Hz), 131.80 (d, J ) 51.9
Hz), 132.49 (d, J ) 64.1 Hz), 132.61 (d, J ) 7.8 Hz), 133.33 (d,
J ) 6.0 Hz), 136.23 (d, J ) 14.0 Hz), 139.56, 160.44 (d, J )
113.1 Hz). 31P{1H} NMR (CD2Cl2): δ 21.2 (d, J ) 38 Hz), 67.6
(d, J ) 38 Hz). Anal. Calcd for C38H45P2BrFePd: C, 56.63; H,
5.64. Found: C, 56.59; H, 5.49.
and less convenient aryl triflates in many coupling
applications.
Exp er im en ta l Section
Gen er a l Meth od s. 1H, 13C, and 31P{1H} NMR spectra were
recorded on a Bruker DPX 400 or 500 MHz spectrometer, a
General Electric QE 300 MHz spectrometer, or a General
Electric Omega 500 spectrometer with tetramethylsilane or
residual protiated solvent as a reference. Elemental analyses
were performed by Robertson Microlabs, Inc., Madison, NJ .
All 31P and 13C NMR spectra were proton decoupled. GC and
GC/MS analyses were conducted with an HP-1 methyl silicone
column. Ether, toluene, tetrahydrofuran, benzene, and pentane
were distilled from sodium/benzophenone. PPF-t-Bu (PPF-t-
Bu ) 1-diphenylphosphino-2-di-tert-butylphosphinoethylfer-
rocene) was purchased from Strem Chemicals and used
without further purification. CyPF-t-Bu (CyPF-t-Bu ) 1-dicy-
clohexylphosphino-2-di-tert-butylphosphinoethylferrocene) was
obtained from Solvias AG and Strem Chemicals and used
without further purification. {Pd[P(o-tolyl)3](Ar)(µ-X)}2,44,45
In d ep en d en t Syn th esis of P d (CyP F -t-Bu )(P h )(Br ) (8).
A solution of 157 mg (0.28 mmol) of CyPF-t-Bu in THF was
added dropwise to a suspension of 150 mg (0.13 mmol) of
{Pd[P(o-tolyl)3](Ph)(µ-Br)}2 in THF. The reaction mixture was
stirred at room temperature for 20 min, during which time
all the solids dissolved. After 20 min the reaction was complete,
as determined by 31P{1H} NMR spectroscopy. The orange
solution was filtered through Celite and concentrated. Addition
of pentane led to precipitation of the product as an orange
solid. The solid was filtered, washed with cold pentane, and
dried under vacuum. The solid was then recrystallized from a
toluene solution layered with pentane and cooled to -35 °C
Pd(dba)2,46 and Pd[P(o-tolyl)3]2 were prepared by literature
45
procedures. Structural data for complexes 7 and 8 have been
1
published previously.35
to give 126 mg (58% yield) of the product. H NMR (C6D6): δ
0.80-2.80 (m, 22 Cy H), 1.32 (d, J ) 12.8 Hz, 9H), 1.61 (t,
Syn th esis of P d (P P F -t-Bu )[P (o-tolyl)3] (5). A solution of
9.1 mg (0.017 mmol) of PPF-t-Bu in C6D6 was added dropwise
to a suspension of 12.0 mg (0.0168 mmol) of Pd[P(o-tolyl)3]2 in
C6D6. The suspension was stirred at room temperature for 10
min, during which time the solids dissolved. The solution was
transferred to an NMR sample tube and was characterized
by 1H and 31P{1H} NMR spectroscopy. 1H NMR (C6D6): δ 0.98
(d, J ) 12.0 Hz, 9H), 1.24 (d, J ) 11.2 Hz, 9H), 1.86 (t, J ) 6.4
Hz, 3H), 2.35 (s, 9H, coordinated P(o-tolyl)3), 3.32 (m, 1H), 3.72
(br s, 1H), 3.86 (s, 5H), 3.91 (t, J ) 2.8 Hz, 1H), 4.18 (br s,
1H), 6.87-7.18 (m, 16H), 7.32 (t, J ) 10.0 Hz, 2H), 7.90 (br s,
2H), 7.99 (br t, J ) 8.0 Hz, 2H). 31P{1H} NMR (C6D6): δ 1.28
(dd, J ) 88 Hz, 88 Hz), 19.78 (br dd, J ) 88 Hz, 82 Hz), 71.69
(dd, J ) 88 Hz, 82 Hz).
1
J ) 7.2 Hz, 3H), 1.67 (d, J ) 11.6 Hz, 9H), 2.19 (s, 1H,
/
3
molecule of toluene), 3.10 (m, 1H), 3.98 (s, 5H), 4.01 (m, 1H),
4.04 (br s, 1H), 4.64 (br s, 1H), 7.01-7.06 (m, 2H), 7.10-7.15
(m, C6D6 and 1/3 molecule of toluene), 7.35 (br, 1H), 7.84 (br,
2H). 31P{1H} NMR (CD2Cl2): δ 19.0 (d, J ) 29 Hz), 74.8 (d,
J ) 34 Hz). Anal. Calcd for C38H57P2BrFePd‚1/3C7H8: C, 57.1;
H, 7.05. Found: C, 57.32; H, 7.19.
In d ep en d en t Syn th esis of P d (P P F -t-Bu )(P h )(OTs) (9).
A solution of 200 mg (0.240 mmol) of Pd(PPF-t-Bu)(Ph)(Br)
(7) in C6H6 was added to a suspension of 68 mg (0.24 mmol) of
AgOTs in C6H6. The reaction was complete after stirring for
20 min, as determined by 31P{1H} NMR spectroscopy. The
suspension was filtered through Celite, and the orange solution
was concentrated under vacuum. Addition of pentane and
stirring of the resulting mixture led to precipitation of the
product as an orange solid. The product was filtered, washed
with pentane, and dried under vacuum to give 162 mg (75%
yield) of product. 1H NMR (CD2Cl2): δ 1.36 (d, J ) 13.2 Hz,
9H), 1.63 (d, J ) 12.0 Hz, 9H), 2.01 (t, J ) 7.2 Hz, 3H), 2.21
(s, 3H), 3.28 (m, 1H), 3.69 (s, 5H), 4.10 (br s, 1H), 4.34 (br s,
1H), 4.61 (br s, 1H), 6.45 (br, 2H), 6.45 (t, J ) 7.2 Hz, 1H),
6.58 (br, 2H), 6.80 (d, J ) 8.4 Hz, 2H), 6.90 (d, J ) 7.6 Hz,
2H), 7.09-7.19 (m, 4H), 7.26-7.31 (m, 1H), 7.59-7.64 (m, 3H),
8.17-8.22 (m, 2H). 13C NMR (CD2Cl2, 40 °C): δ 17.71 (d, J )
5.0 Hz), 21.30, 31.64 (d, J ) 5.9 Hz), 31.70 (d, J ) 6.8 Hz),
32.43 (m), 37.47, 38.52, 68.62 (d, J ) 7.0 Hz), 70.88 (d, J )
8.3 Hz), 70.95, 75.73 (d, J ) 5.2 Hz), 78.26 (dd, J ) 47.63,
10.80 Hz), 95.96 (dd, J ) 16.8, 6.5 Hz), 123.22, 126.40, 126.77,
128.04 (d, J ) 11.3 Hz), 128.31, 128.77 (d, J ) 11.4 Hz), 129.92
(J ) 2.8 Hz), 131.77 (br), 132.12 (d, J ) 58.1 Hz), 132.24 (d,
J ) 58.1 Hz), 133.73 (d, J ) 9.6 Hz), 136.02 (d, J ) 12.6 Hz),
136.67 (br), 139.05, 140.95, 157.83 (d, J ) 103.3 Hz). 31P{1H}
NMR (CD2Cl2): δ 25.4 (d, J ) 37 Hz), 67.5 (d, J ) 37 Hz).
Anal. Calcd for C45H52P2O3SFePd: C, 60.24; H, 5.85. Found:
C, 59.94; H, 5.78.
Syn th esis of P d (CyP F -t-Bu )[P (o-tolyl)3] (6). A solution
of 9.4 mg (0.017 mmol) of CyPF-t-Bu in C6D6 was added
dropwise to a suspension of 12.1 mg (0.0169 mmol) of Pd[P(o-
tolyl)3]2 in C6D6. The suspension was stirred at room temper-
ature for 10 min, during which time the solids dissolved. The
solution was transferred to an NMR sample tube and was
1
characterized by H and 31P{1H} NMR spectroscopy. 1H NMR
(C6D6): δ 0.90-2.0 (m, 22 Cy H), 1.05 (br d, J ) 8.8 Hz, 9H),
1.26 (d, J ) 11.6 Hz, 9H), 1.88 (t, J ) 6.8 Hz, 3H), 2.2-2.6
(br, 9H), 3.15 (m, 1H), 4.05 (t, J ) 2.0 Hz, 1H), 4.13 (s, 5H),
4.25 (br s, 1H), 4.36 (br s, 1H), 6.99-7.10 (m, 12H). 31P{1H}
NMR (C6D6): δ 11.72 (br), 21.42 (br), 69.59 (t, J ) 88 Hz).
In d ep en d en t Syn th esis of P d (P P F -t-Bu )(P h )(Br ) (7).
A solution of 218 mg (0.400 mmol) of PPF-t-Bu in THF was
added dropwise to a suspension of 200 mg (0.180 mmol) of
{Pd[P(o-tolyl)3](Ph)(µ-Br)}2 in THF. The reaction mixture was
stirred at room temperature for 20 min, during which time
all the solids dissolved. After 20 min the reaction was complete,
as determined by 31P{1H} NMR spectroscopy. The orange
solution was filtered through Celite and concentrated. Addition
of pentane led to precipitation of 226 mg (78% yield) of the
product as an orange solid. The product was filtered, washed
1
with pentane, and dried under vacuum. H NMR (CD2Cl2): δ
In d ep en d en t Syn th esis of P d (CyP F -t-Bu )(P h )(OTs)
(10). A solution of 113 mg (0.140 mmol) of Pd(CyPF-t-Bu)(Ph)-
(Br) (8) in C6H6 was added to a suspension of 48 mg (0.17
mmol) of AgOTs in C6H6. The reaction was complete after
stirring for 20 min, as determined by 31P{1H} NMR spectros-
copy. The suspension was filtered through Celite, and the
orange solution was concentrated under vacuum. Addition of
pentane and stirring of the resulting mixture led to precipita-
tion of the product as an orange solid. The product was filtered,
washed with pentane, and dried under vacuum to give 90 mg
1.39 (d, J ) 12.8 Hz, 9H), 1.72 (d, J ) 12.0 Hz, 9H), 2.07 (t,
J ) 8.0 Hz, 3H), 3.43 (m, 1H), 3.67 (s, 5H), 4.22 (m, 1H), 4.33
(m, 1H), 4.59 (m, 1H), 6.36-7.28 (m, 10H), 7.60-7.66 (m, 3H),
8.18-8.24 (m, 2H). 13C NMR (CD2Cl2, -15 °C): δ 18.18 (d,
J ) 3.0 Hz), 31.05 (d, J ) 4.3 Hz), 32.00 (br), 32.66 (dd, J )
(44) Widenhoefer, R. A.; Zhong, H. A.; Buchwald, S. L. Organome-
tallics 1996, 15, 2745.
(45) Paul, F.; Patt, J .; Hartwig, J . F. Organometallics 1995, 14, 3030.
(46) Komiya, S. In Synthesis of Organometallic Compounds:
Practical Guide; Wiley: New York, 1997; p 290.
A
1
(71% yield) of product. H NMR (CD2Cl2): δ 0.76-2.95 (m, 22

202 Organometallics, Vol. 23, No. 2, 2004
Roy and Hartwig
Cy H), 1.11 (d, J ) 13.5 Hz, 9H), 1.62 (d, J ) 12.0 Hz, 9H),
1.92 (t, J ) 8.0 Hz, 3H), 2.26 (s, 3H), 3.02 (m, 1H), 4.26 (s,
5H), 4.52 (t, J ) 2.0 Hz, 1H), 4.56 (br s, 1H), 4.95 (br s, 1H),
6.79-6.84 (m, 4H), 6.89 (d, J ) 7.0 Hz, 2H), 7.05-7.12 (m,
3H). 31P{1H} NMR (C7H8, -40 °C): δ 25.2 (d, J ) 31.9 Hz),
71.6 (d, J ) 30.5 Hz). Anal. Calcd for C45H64P2O3SFePd: C,
59.44; H, 7.11. Found: C, 59.71; H, 7.34.
Gen er a l P r oced u r e for th e Oxid a tive Ad d ition of
Ar OTf to 1. Into a small vial was placed 15 mg (0.021 mmol)
of Pd[P(o-tolyl)3]2, 56 mg (0.24 mmol) of PhOTs, 115 mg (0.21
mmol) of N(octyl)4Br, and PMes3 as internal standard. The
reactants were dissolved in 1 mL of C6H6, and the resulting
solution was stirred at room temperature. A 31P{1H} NMR
spectrum was obtained periodically until all starting material
had been consumed. The yield of compound 3 was calculated
to be 99% yield.
17.3 mg (0.0697 mmol) of PhOTs, and the resulting solution
was stirred at room temperature. After 30 min, a second
31P{1H} NMR spectrum was obtained, and this spectrum
showed that all starting material had been consumed and that
compound 10 was produced in 92% yield.
Mea su r em en t of Ra te Con sta n t for Oxid a tive Ad d i-
tion of Ar yl Tr ifla te to P a lla d iu m (0): Rep r esen ta tive
P r oced u r e. Into a small vial was placed 2.5 mg (0.0035 mmol)
of Pd[P(o-tolyl)3]2, 10 µL (0.056 mmol) of p-tolylOTf, 31.0 mg
(0.0567 mmol) of N(octyl)4Br, 0.20 mL (0.020 mmol) of a 0.1
M solution of P(o-tolyl)3 in C6D6, and PMes3 as internal
standard. Exactly 0.40 mL of C6H6 was added to the vial, and
the solution was transferred to an NMR tube with a septum-
lined screw cap. The sample was heated to 50 °C, and 31P{1H}
NMR spectra were obtained every 3 min for at least 5 half-
lives by an automated data acquisition program.
Gen er a l P r oced u r e for th e Oxid a tive Ad d ition of
P h OTf to 5 a n d 6. Into a small vial was placed 10 mg (0.014
mmol) of Pd[P(o-tolyl)3]2, 7.7 mg (0.014 mmol) of PPF-t-Bu,
and 11.6 mg of PMes3 as internal standard. The solid materials
were dissolved in 1 mL of C6H6 and stirred at room temper-
ature for 10 min. The solution was transferred to an NMR
tube. A 31P{1H} NMR spectrum was obtained. The solution
was poured into a vial containing 12 µL (0.074 mmol) of PhOTf
and 79 mg (0.14 mmol) of N(octyl)4Br, and the resulting
solution was stirred at room temperature. After 10 min, a
second 31P{1H} NMR spectrum was obtained, and this spec-
trum showed that all starting material had been consumed
and that compound 7 was produced in 93% yield.
Mea su r em en t of Ra te Con sta n t for Oxid a tive Ad d i-
tion of Ar yl Tosyla te to P a lla d iu m (0): Rep r esen ta tive
P r oced u r e. Into a small vial was placed 12.0 mg (0.0170
mmol) of Pd[P(o-tolyl)3]2, 9.2 mg (0.017 mmol) of PPF-t-Bu,
34.0 mg (0.140 mmol) of PhOTs, 92.0 mg (0.170 mmol) of
N(octyl)4Br, 26.0 mg (0.0850 mmol) of P(o-tolyl)3, and PMes3
(as internal standard). The solids were dissolved in 0.60 mL
of THF, and the solution was transferred to an NMR tube with
a septum-lined screw cap. The sample was heated to 55 °C,
and 31P{1H} NMR spectra were obtained every 3 min for at
least 5 half-lives by an automated data acquisition program.
Gen er a l P r oced u r e for th e Oxid a tive Ad d ition of
P h OTs to 5 a n d 6. Into a small vial was placed 10.0 mg
(0.0140 mmol) of Pd[P(o-tol)3]2, 7.8 mg (0.0140 mol) of CyPF-
t-Bu, and 5.4 mg of PMes3 as internal standard. The solid
materials were dissolved in 0.60 mL of C6H6, and the solution
was transferred to an NMR tube. A 31P{1H} NMR spectrum
was obtained. The solution was poured into a vial containing
Ack n ow led gm en t . We thank the NIH-NIGMS
(Grant No. GM-55382) for support of this work. We also
thank Merck Research Laboratories for unrestricted
support and J ohnson-Matthey for palladium salts. Dr.
Luis Alcazar-Roman obtained the single crystal of 7.
OM034187P