Palladium(II) 3-iminophosphine (3IP) complexes: Active precatalysts for the intermolecular hydroamination of 1,2-dienes (allenes) and 1,3-dienes with aliphatic amines under mild conditions

Article abstract of DOI:10.1016/j.jorganchem.2010.08.033

The synthesis of alicyclic 3-iminophosphine ligands is extended to include a new framework incorporating a cyclohexenyl backbone with an N-aryl imino functionality (3IP^Ar). Accordingly, a series of palladium(II) complexes employing this new lig

Full text of DOI:10.1016/j.jorganchem.2010.08.033

Journal of Organometallic Chemistry 696 (2011) 179e187
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Journal of Organometallic Chemistry
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Palladium(II) 3-iminophosphine (3IP) complexes: Active precatalysts for the
intermolecular hydroamination of 1,2-dienes (allenes) and 1,3-dienes with
aliphatic amines under mild conditions
*
Glenn Kuchenbeiser, Andrew R. Shaffer, Nicholas C. Zingales, John F. Beck, Joseph A.R. Schmidt
Department of Chemistry, The University of Toledo, 2801 W. Bancroft St. MS 602, Toledo, OH 43606 3390, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
The synthesis of alicyclic 3-iminophosphine ligands is extended to include a new framework incorpo-
rating a cyclohexenyl backbone with an N-aryl imino functionality (3IPAr). Accordingly, a series of
palladium(II) complexes employing this new ligand have been synthesized and utilized in the inter-
molecular hydroamination of 3-methyl-1,2-butadiene (1,1-dimethylallene) and 2,3-dimethyl-1,3-buta-
diene with secondary amines. The complex [(3IPAr)Pd(allyl)]OTf displays excellent catalytic activity in
these reactions, selectively producing allylic amine products in high conversion under mild conditions,
with an improved rate relative to that observed for our previously reported catalysts. Further, the
reactivity trends for the (3IP)Pd triflate systems prove to be complimentary to other known late tran-
sition metal based catalytic systems.
Received 19 July 2010
Received in revised form
23 August 2010
Accepted 24 August 2010
Available online 1 October 2010
Keywords:
Hydroamination
Allenes
Butadienes
Palladium
Ó 2010 Elsevier B.V. All rights reserved.
Iminophosphines
Catalysis
1. Introduction
temperatures (between 70 and 130 ꢀC) were required, and the cost
of gold precursors is non-trivial. Clearly, the discovery of more mild
The formation of CeN bonds is essential to the synthesis of a wide
variety of pharmaceutically and industrially important nitrogen
containing organic molecules [1,2]. Although there are a number of
reliable methods for making these bonds, by far the most atom-effi-
cient routes involve the direct addition of NeH across unsaturated
CeC bonds, a process known as hydroamination [3e10]. A variety of
late transitionmetalcatalyzed intramolecularvariants of thisreaction
have been reported, allowing the formation of nitrogen containing
heterocycles [11e32]. For obvious entropic reasons, intermolecular
hydroamination has proven to be more challenging, especially with
unactivated alkenes, and so the discovery of new catalysts effecting
this reaction remains a very active topic of research.
Recently Bertrand and co-workers reported the catalytic inter-
molecular Markovnikov hydroamination of allenes with primary
and secondary amines, as well as ammonia, utilizing a cationic
goldecarbene complex [33,34]. Additionally, the Widenhoefer
group has shown similar reactivity using a gold-phosphine/AgOTf
system [35] and other gold-based systems [36e39]. While these
systems display excellent activity, in both cases elevated reaction
catalytic methodologies would be advantageous.
Previously, we reported a series of 3-iminophosphine (3IP)
palladium(II) complexes that display hemilabile behavior (Fig. 1)
[40,41]. One of these complexes, the triflate salt of [(3IP)Pd(allyl)]þ,
was shown to have moderate catalytic activity for the intermolec-
ular hydroamination reactions of 1,3-cyclohexadiene and phenyl-
acetylene with primary and secondary amines to yield enamines
and imines without the need for an acid co-catalyst [41]. Expanding
on these previous results, we now report the synthesis of a new
3IP framework containing a cyclohexenyl alicyclic backbone with
N-aryl substituted imine and have found that the corresponding
(3IPAr)Pd triflates are active precatalysts in the intermolecular
hydroamination of acyclic 1,2- and 1,3-dienes giving high conver-
sion to allylic amine products under mild conditions.
2. Results and discussion
2.1. Synthesis and characterization
The modular and general methodology used for the synthesis of
the 3-iminophosphine (3IP) ligand framework allows a great deal
of flexibility with regards to both steric and electronic parameters
* Corresponding author. Tel.: þ1 419 530 1512; fax: þ1 419 530 4033.
E-mail address: Joseph.Schmidt@utoledo.edu (J.A.R. Schmidt).
0022-328X/$ e see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2010.08.033

180
G. Kuchenbeiser et al. / Journal of Organometallic Chemistry 696 (2011) 179e187
Ph Ph
P
Ph Ph
Ph
Ph
Ph Ph
P
Ph
Ph
P
PdCl2
PdCl2
Pd
Cl
OTf
P
P
N
PdCl2
N
Pd(OTf)2
Pd
N
Ar
Ar
(3IP )PdCl2
PPh2
NAr
N
tBu
tBu
tBu
N
tBu
(3IP)Pd(allyl)Cl [(3IP)Pd(allyl)][OTf]
Ph Ph
Ph Ph
P
0.5 eq.
[Pd(allyl)Cl]2
OTf
P
(3IP)PdCl2
(3IP)Pd(OTf)2
Ar
Pd
3IP
AgOTf
- AgCl
Pd
Cl
N
Fig. 1. Previously reported 3IPepalladium complexes tested in this study (OTf ¼ CF3SO3).
Ar
[(3IP )Pd(allyl)]OTf
N
Ar = 2,6-Me2C6H3
Ar
Ar
(3IP )Pd(allyl)Cl
Ar
available for complexation to a transition metal center. With this in
mind, we sought to synthesize a new 3IP ligand and its corre-
sponding Pd complexes in order to explore the effect of altered
substituents on catalytic efficiency in hydroamination reactions.
Specifically, substitution of the imine nitrogen with an aryl rather
than an alkyl group was anticipated to yield weaker coordination to
a metal center, while 2,6-disubstitution of the aryl ring should
encourage imine lability due to increased projection of steric bulk
towards the metal center. We expected the combination of these
features to allow for better access to a vacant coordination site for
catalysis.
Scheme 2. Synthesis of N-aryl-3-iminophosphine palladium complexes.
of (3IPAr)PdCl2 are very similar to that reported for (3IP)PdCl2 [41]
with all of the notable bond lengths being nearly equal between the
two complexes (Table 1). The main differences in the observed
metrical parameters involve the bond angles associated with the
ligand backbone, which are likely an effect of the different ring sizes
within the alkenyl ligand framework.
We next sought to synthesize the 3IPAr analog of our reported
hydroamination catalyst: [(3IP)Pd(allyl)]OTf [41]. Combining room
temperature methylene chloride solutions of 3IPAr and [Pd(allyl)
Cl]2, stirring overnight, and subsequent workup gave a yellow
microcrystalline solid in 95% yield. The 31P NMR spectrum of
a room temperature CDCl3 solution of this material shows a singlet
at 19.1 ppm, shifted downfield from the free ligand by nearly
32 ppm and similar to that of the corresponding 3IP analog. Notable
features of the 1H NMR spectrum include a doublet at 8.81 ppm
(4JPH ¼ 3.6 Hz) for the imine proton resonance and the equivalency
The 3-iminophosphine ligand system (3IPAr) used in this study
was synthesized in excellent yield using a sequence analogous to
that reported in our earlier work (Scheme 1) [41]. Treatment of
commercially available cyclohexanone with the Vilsmeier-Haack
reagent and subsequent workup gave an alicyclic
-chloroaldehyde in 90% yield as a red liquid (intermediate a;
Scheme 1). Schiff base condensation using 2,6-dimethylaniline at
0 ꢀC provided the corresponding
-chloroimine (intermediate b) as
a,b-unsaturated,
b
b
a red oil in 96% yield. The ligand synthesis was completed by
reaction with lithium diphenylphosphide in toluene at ꢁ78 ꢀC to
afford an off-white solid in 88% yield. 31P NMR spectroscopy
revealed a distinctive signal at ꢁ12.6 ppm, while the 1H NMR
spectrum displayed a characteristic doublet for the imine proton at
9.05 ppm (4JPH ¼ 9.0 Hz).
of aryl-methyl resonances at 1.88 ppm, indicating a k
1 coordination
mode. Additional data from 13C NMR spectroscopy and high reso-
lution mass spectrometry confirmed the identity of the product as
(3IPAr)Pd(allyl)Cl.
Halogen abstraction from (3IPAr)Pd(allyl)Cl with silver triflate
in methylene chloride and subsequent workup gave a new yellow
solid in 88% yield. The room temperature 31P NMR spectrum in
CDCl3 revealed a single resonance at 25.2 ppm, further downfield
shifted from both the precursor and free ligand. As in the case
of (3IPAr)PdCl2, the 1H NMR signal for the imine proton was
found significantly upfield (7.70 ppm) from that of free ligand
(3IPAr: 9.05 ppm) or the precursor complex ((3IP)Pd(allyl)Cl:
8.81 ppm), consistent with a k2 coordination mode. This analysis
was confirmed by the presence of two singlets at 2.06 and
1.95 ppm, corresponding to inequivalent aryl-methyl groups due to
hindered rotation of the N-aryl ring in the [(3IPAr)Pd(allyl)]OTf
complex. X-ray quality crystals were grown by slow diffusion of
pentane into a THF solution of this complex. The crystal structure of
[(3IPAr)Pd(allyl)]OTf confirmed the k2 coordination mode in this
complex (Fig. 3). In a similar fashion to that observed for [(3IP)Pd
(allyl)]PF6 [40] the allyl group was disordered as a 4:1 ratio of the
cis and trans isomers, while the two distal carbon atoms of the
cyclohexenyl ring were disordered in a nearly 1:1 ratio of two
different boat-like conformations. Surprisingly, an examination of
the bond lengths in this complex revealed stronger bonding of the
imine nitrogen to the palladium center, as noted by the significantly
shorter Pd1eN1 bond length in [(3IPAr)Pd(allyl)]OTf than was
observed in the previous [(3IP)Pd(allyl)]OTf complex (Table 1). All
of the other notable bond lengths were found to be quite similar for
the two complexes. Significant differences in the bond angles were
also observed, with the ligand bite angle for the (3IPAr) complex
found to be almost ideal at 90.44(6) degrees. The various differ-
ences in bond angles are most likely the result of the cyclohexenyl
backbone in this new complex, relative to the cyclopentenyl back-
bone of the previously reported 3IP complex. In fact, the shorter
In order to examine the coordination chemistry of 3IPAr, and for
comparison with our previously reported 3IP complexes, we began
with the classical precursor PdCl2 (Scheme 2). Addition of a solution
of 3IPAr in methylene chloride to a slurry of PdCl2 in acetonitrile,
stirring overnight and subsequent workup resulted in a yellow
powder in 60% yield. The new compound was identified spectro-
scopically as the desired species (3IPAr)PdCl2. Room temperature
31P NMR spectroscopy of this compound in CDCl3 shows a singlet at
30.3 ppm, shifted significantly downfield from that for the free
ligand (ꢁ12.6 ppm), while the 1H and 13C NMR spectra are analo-
gous to our previously reported (3IP)PdCl2. The imine proton
resonance shifts significantly upfield to 7.46 ppm in (3IPAr)PdCl2,
consistent with coordination of the nitrogen atom to the palladium
center. Single crystals suitable for an X-ray diffraction study were
obtained by slow evaporation of a chloroform solution, confirming
the proposed k2 coordination mode (Fig. 2). In the solid state, the
complex has a distorted square planar geometry with a ligand bite
angle of 88.6ꢀ and a significant folding of the ligand to give a boat-
like conformation. This overall shape and the structural parameters
Ph2P
NAr
O
Cl
O
Cl NAr
iv
i
iii
ii
Ar
a
b
3IP
Scheme 1. Synthesis of alicyclic (cyclohexenyl) 3IPAr ligand (Ar
¼
2,6-Me2C6H3).
Legend: (i) POCl3, DMF, 0 ꢀC, 30 min; (ii) ice, NaHCO3; (iii) H2N(2,6-Me2C6H3), Et2O,
0
ꢀC, 14 h; (iv) Ph2PLi, toluene, ꢁ78 ꢀC, 14 h.

G. Kuchenbeiser et al. / Journal of Organometallic Chemistry 696 (2011) 179e187
181
Fig. 3. ORTEP diagram (50% thermal ellipsoids) of [(3IPAr)Pd(allyl)]OTf. Hydrogen
atoms, three disordered carbon atoms and THF solvent molecule omitted for clarity.
Fig. 2. ORTEP diagram (50% thermal ellipsoids) of (3IPAr)PdCl2. Hydrogen atoms and
two chloroform solvent molecules omitted for clarity.
as well as a second set of resonances corresponding to the linear
olefin product 2a, in a ratio of ca. 2:1 with a total conversion of 91%
within 30 min. Within 4 h, the reaction proceeded with complete
regioselectivity, quantitatively forming the allylic amine product
2a, afforded via isomerization of the kinetic branched product
(Table 2, entry 12). Reduction of the catalyst loading to 1 mol% also
gave quantitative conversion to 2a, but at a five fold increase in
reaction time. To the best of our knowledge, this is the first example
of room temperature hydroamination of allenes with dialkylamines
using a late transition metal catalyst.
Pd1eN1 bond length may also reflect changes caused by the
different backbone unit, as it may now have less ring strain than
was originally observed in the initial report. Clearly, the study of
further ligand derivatives is necessary to fully delineate the effects
of imine substituent and backbone composition.
2.2. Catalysis
While moderate success was achieved in the hydroamination of
both phenylacetylene and 1,3-cyclohexadiene using [(3IP)Pd
(allyl)]OTf, these results were limited by competing cyclo-
trimerization and aromatization reactions, as evidenced by the
formation of aryl side products and the need for a large excess of
diene/alkyne present [41]. Therefore, it was preferable to explore
substrates not plagued by these competitive pathways. 1,2-Dienes
(allenes) constitute an important class of unsaturated substrates
that have recently been shown to undergo hydroamination via
cationic transition metal catalysts [33,42] so we postulated that
our cationic 3IP-palladium systems may display similar catalytic
activity for allene hydroamination. Preliminary screening was
performed using 5 mol% of [(3IPAr)Pd(allyl)]OTf at room temper-
ature with 3-methyl-1,2-butadiene and morpholine as reactants.
Upon monitoring the reaction progress by 1H NMR spectroscopy in
deuterated benzene, we observed the formation of a new set of
resonances consistent with a branched hydroamination product 1a,
Although all of our 3IP and 3IPAr Pd triflates were found to be
competent hydroamination catalysts at 5 mol% loading, the best
reaction rate was obtained using [(3IPAr)Pd(allyl)]OTf (Table 2,
entries 10e13). As expected, the various corresponding (3IP)Pd
chloride complexes showed no activity, even at extended reaction
times, higher temperatures, or with the addition of silver triflate
(Table 2, entries 4e9). The detrimental effect of chloride ions is
Table 2
Hydroamination of 3-methyl-1,2-butadiene with morpholinea.
H
H
5 mol%
N
H
C
Pd
+
CH2
C
N
O
C6D6
N
O
O
25 oC
1a
2a
Table 1
Selected bond distances (Å) and angles (deg) in crystal structuresa.
Entry
Precatalyst
Time (h)
Conversion (%)b
(3IP)PdCl2 (3IPAr)PdCl2 [(3IP)Pd(allyl)]OTf [(3IPAr)Pd(allyl)]OTf
1
2
3
4
5
6
7
8
PdCl2
[Pd(allyl)Cl]2
48
48
48
48
48
48
48
48
48
4
20
4
20
24
4
none
none
none
none
none
none
none
none
Pd1eP1
Pd1eN1
Pd1eClP
Pd1eClN
Pd1eCP
Pd1eCN
P1eC3
N1eC1
C1eC2
C2eC3
2.226(1) 2.220(1)
2.065(4) 2.054(4)
2.396(1) 2.362(1)
2.298(1) 2.289(1)
2.267(5)
2.141(3)
e
2.2597(6)
2.080(2)
e
[Pd(allyl)Cl]2 þ 2 AgOTf
(3IP)PdCl2
(3IPAr)PdCl2
e
e
e
e
2.238(5)
2.102(4)
1.81(1)
1.284(1)
1.465(4)
1.342(3)
92.9(5)
105.6(9)
123.5(8)
127.8(9)
129.8(2)
2.210(2)
2.110(2)
1.826(2)
1.283(3)
1.476(3)
1.347(3)
90.44(6)
111.45(7)
129.7(2)
128.5(2)
126.9(2)
(3IP)PdCl2 þ 2 AgOTf
(3IPAr)PdCl2 þ 2 AgOTf
(3IP)Pd(allyl)Cl
e
e
1.804(4) 1.817(5)
1.285(6) 1.278(6)
1.463(6) 1.478(6)
1.351(6) 1.343(6)
9
(3IPAr)Pd(allyl)Cl
[(3IP)Pd(allyl)]OTf
[(3IP)Pd(allyl)]OTf
[(3IPAr)Pd(allyl)]OTf
(3IP)Pd(OTf)2
none
10
11
12
13
14
15
45 (1a) þ 44 (2a)
>98 (2a)
>98 (2a)
>98 (2a)
70 (2a)
97 (2a)
P1ePd1eN1 85.3(7)
88.6(1)
Pd1eP1eC3 100.2(2) 108.2(1)
Pd1eN1eC1 123.1(2) 126.5(3)
N1eC1eC2 123.6(2) 128.7(4)
C1eC2eC3 124.1(9) 124.1(4)
[(3IPAr)Pd(allyl)]OTf þ NEt3
[(3IPAr)Pd(allyl)]OTf þ HBF4
a
Conditions: 0.32 mmol allene, 0.32 mmol morpholine, 0.5 mL C6D6, 25 ꢀC, sealed
a
Superscripted letters indicate the atom positioned trans to the denoted atom.
NMR tube.
b
Conversion determined by 1H NMR spectroscopy.
Data for 3IP complexes reproduced from Ref. [41].

182
G. Kuchenbeiser et al. / Journal of Organometallic Chemistry 696 (2011) 179e187
Table 4
consistent with other reports in the literature [43]. The addition of
1 eq. of a strong acid (HBF4$OEt2) proved to have no effect on
reaction rate or conversion, while the addition of an amine base
(triethylamine) slowed the catalysis such that product formation
was reduced to 70% after 24 h (Table 2, entries 14e15). This result is
consistent with competitive inhibition at the metal center and
perhaps explains the significant decrease in rate over time
observed for all of our catalyses, as tertiary amine bases constitute
the hydroamination reaction products. Additionally, control
experiments using silver triflate, palladium allyl chloride dimer,
palladium(II) chloride, or their mixtures resulted in no conversion
to hydroamination products (Table 2, entries 1e3), indicating the
necessity of the preformed 3IPePd triflate complexes in order to
achieve catalysis. Solvent screening revealed that non-polar,
aromatic solvents such as benzene and toluene afforded the highest
conversions, while reactions performed in either acetonitrile or
chloroform displayed reduced catalytic efficiency (Table 3, entries
1e4). Furthermore, the presence of significant amounts of a donor
solvent (THF) did not significantly decrease the catalytic efficiency
(Table 3, entry 5).
Catalytic hydroamination of 3-methyl-1,2-butadiene with secondary amines using
[(3IPAr)Pd(allyl)]OTf a
.
H
C
cat.
+ HNR2
C CH2
C6D6
RT
NR2
1
NR2
2
Entry
1
Amine
Time (hrs)
Product
Conversion (%)b
4
2a
>98
HN
O
2
3
<1
2b
2c
>98
>98
HN
HN
N
S
3
4
5
6
6
2d
2e
e
>98
>98
e
Using our optimized conditions, we examined the scope of
secondary amines amenable to the hydroamination of 3-methyl-
HN
HN
1,2-butadiene using
5
mol% [(3IPAr)Pd(allyl)]OTf as catalyst
(Table 4). Both cyclic and acyclic dialkylamines were the best
substrates for this reaction, with each giving quantitative conver-
sion to the linear products at room temperature in less than 6 h
(Table 4, entries 1e12). Exceptions to this occurred only for the
bulky substrates 2,2,6,6-tetramethylpiperidine and diisopropyl-
amine. In general, cyclic N-aryl-alkylamines proved to be more
challenging substrates (Table 4, entries 13e15). For example, the
reaction with indoline gave a quantitative conversion at room
temperature but required 24 h. Moreover, reactions involving the
bulkier 2-methylindoline or 1,2,3,4-tetrahydroquinoline gave only
poor to moderate results and required elevated temperatures and
long reaction times. Lastly, all attempts at hydroamination using N-
methyl aniline resulted in the rapid formation of Pd black without
any detectable hydroamination products. So, overall the reactivity
trend for the [(3IPAr)Pd(allyl)]OTf catalytic system appears to favor
more basic amines, in stark contrast with other known catalysts
that have more success with the less basic amines [33,35,43].
Additionally, hydroamination product isolation was straightfor-
ward with excellent recovery (>80%) of the amines produced.
Conjugated dienes constitute another class of unsaturated
substrates of interest for intermolecular hydroamination. These
reactions typically result in the formation of mixtures of telome-
rization products, with 1:1 adducts formed in variable yields
depending upon the substrate and catalyst employed [4,44]. A
notable exception is found in the work of Yoshifuji employing
a diphosphinidenecyclobutane Pd catalyst, where the reaction of
aniline with various conjugated dienes selectively gave high yields
of the desired allylic amine products, although the scope of amine
substrates was not explored [45]. Given our success in the inter-
molecular hydroamination of 3-methyl-1,2-butadiene, we also
6
48
HN
7
8
9
10
11
12
HNEt2
3
3
48
4
30
3
2f
2g
e
>98
>98
e
HNnBu2
HNiPr2
HN(Me)(nBu)
HN(CH2Ph)2
2h
2i
2j
>98
>98c
>98
NH
13
14
15
24
2k
2l
>98
N
H
,
e
e
24(96)
24(96)
28(55)d
11(25)d
N
H
,
2m
N
H
16
HN(Me)(Ph)
48
e
ef
Conditions: 0.32 mmol allene, 0.32 mmol amine, 5 mol% [(3IPAr)Pd(allyl)]OTf,
a
0.5 mL C6D6, 25 ꢀC, sealed NMR tube.
Conversion measured by 1H NMR spectroscopy.
b
c
Reaction at 50 ꢀC.
Table 3
d
Reaction at 90 ꢀC.
Effect of solvent on Pd catalyzed hydroamination of 3-methyl-1,2-butadiene with
morpholinea.
e
Conversion in parenthesis after 4 d.
Pd black rapidly formed.
f
Entry
Solvent
Conversion (%)b
1
2
3
4
5
Benzene
Toluene
Acetonitrile
Chloroform
Benzene/THF (1:1)
>98
>98
48
12
>98
chose to examine hydroamination of the commercially available
2,3-dimethyl-1,3-butadiene. Although this substrate proved to be
more challenging than dimethylallene, requiring heating at 60 ꢀC
for 24 h or more depending on the amine employed, allylic amine
products were obtained for a variety of amines. While primary
amines showed no conversion, secondary dialkylamines readily
a
Conditions: 0.32 mmol allene, 0.32 mmol morpholine, 5 mol% [(3IPAr)Pd(allyl)]
OTf, 0.5 mL solvent, 25 ꢀC, 24 h, sealed NMR tube.
b
Conversion determined by 1H NMR spectroscopy.

G. Kuchenbeiser et al. / Journal of Organometallic Chemistry 696 (2011) 179e187
183
underwent 1,4-addition to afford the corresponding tertiary allylic
amine products (Table 5). The best results were obtained for cyclic
secondary amines, such as morpholine and piperidine (Table 5,
entries 1e5). Non-cyclic secondary amines provided moderate
conversion at best, while the bulkier substrates showed little or no
reactivity at all (Table 5, entries 6e9). Cyclic N-aryl-alkylamines
were again quite sluggish with only indoline providing notable
conversion after a 72 h reaction period (Table 5, entry 11). In
general, the hydroamination of 2,3-dimethyl-1,3-butadiene with
secondary amines provided only moderate product formation and
required long reaction times, limiting the utility of the [(3IPAr)Pd
(allyl)]OTf catalyst for reactions with this substrate.
previously reported (3IP)Pd species. Despite the ligand similarities,
the 3IPAr catalytic system shows increased catalytic activity in the
intermolecular hydroamination of 1,2- and 1,3-dienes relative to its
3IP counterparts. Based on the differences observed by comparison
of the catalyst crystal structures, this improved reactivity seems to
be caused by the larger backbone alicyclic ring, although we can not
rule out the effect of changes to the imine basicity or increased
imine steric interactions leading to greater lability and therefore
a more accessible vacant site at the Pd center. The reactivity trends
for these systems are complimentary to other known late transition
metal based catalytic systems with highly basic secondary dia-
lkylamines proving to be the best substrates, leading to quantitative
conversion to allylamine products within hours at room tempera-
ture. Further exploration of ligand parameters for our 3IP systems
and their effect on catalytic activity are currently underway.
3. Conclusions
The synthesis of a new alicyclic 3-iminophosphine ligand has
been achieved with the formation of a cyclohexenyl based N-aryl
imino 3IP ligand (3IPAr). Reactions with Pd precursors yielded
a variety of 3IPAr palladium(II) complexes whose spectroscopic and
structural parameters matched well with the corresponding
4. Experimental
4.1. General considerations
Intermediates a and b were synthesized under ambient atmo-
sphere. All other reactions were performed using standard Schlenk
and drybox techniques. n-Butyllithium (1.6 M in hexanes), palla-
dium(II) chloride, (allyl)palladium(II) chloride dimer, chlor-
odiphenylphosphine, and silver triflate were purchased from Strem
and used without further purification. CDCl3 and C6D6 were
purchased from Cambridge Isotope Laboratories and vacuum
transferred from CaH2 and Na/benzophenone ketyl, respectively.
Pentane, tetrahydrofuran, and methylene chloride were purified by
passage through a column of activated 4 Å molecular sieves and
degassed with nitrogen prior to use. Diethyl ether and toluene were
purified by passage through a column of activated alumina and
a column of activated 4 Å molecular sieves and degassed with
nitrogen prior to use. Acetonitrile and chloroform were purified by
vacuum transfer from CaH2. Cyclohexanone, POCl3, N,N-dime-
thylformamide, sodium, 3-methyl-1,2-butadiene, 2,3-dimethyl-1,3-
butadiene, and all amines were purchased from commercial
vendors. All amines used for hydroamination were dried by vacuum
transfer from CaH2$LiPPh2 [41], (3IP)PdCl2 [41], (3IP)Pd(allyl)Cl
[41], [(3IP)Pd(allyl)]OTf [41], and (3IP)Pd(OTf)2 [40] were
synthesized as previously reported. NMR data were obtained on
Inova 600 or 400 MHz or Gemini 200 MHz spectrometers at
ambient temperature. NMR chemical shifts are given relative to
residual solvent peaks and were taken in CDCl3, unless otherwise
noted. 31P and 19F NMR spectra were externally referenced to
0.00 ppm with 5% H3PO4 in D2O and CFCl3, respectively. IR samples
were prepared as Nujol mulls or neat films and taken between KBr
plates on a PerkineElmer XTL FTIR spectrophotometer. Melting
points were observed on a Mel-Temp apparatus in sealed capillary
tubes and are uncorrected. Elemental analyses were determined by
Desert Analytics, Tucson, AZ and Galbraith Laboratories, Knoxville,
TN. High resolution mass spectrometry analysis was performed by
the University of Illinois Mass Spectrometry Laboratory, Urbana, IL.
X-ray structure determinations were performed at the Ohio Crys-
tallographic Consortium housed at The University of Toledo.
Table 5
Catalytic hydroamination of 2,3-dimethyl-1,3-butadiene with secondary amines
using [(3IPAr)Pd(allyl)]OTf a
.
5 mol% Pd
C6D6, 60 o
+ HNR2
C
NR2
3
Entry
1
Amine
Product
Conversion (%)b
89
3a
3b
3c
3d
3e
HN
O
N
2
3
4
5
38(49)c
49
HN
HN
HN
S
85
40(56)c
HN
6
7
8
9
HNEt2
3f
3g
e
38(55)c
15(36)c
e
HNnBu2
HNiPr2
HN(CH2Ph)2
e
<5
10
3j
69(87)c
NH
11
3k
18(74)c
4.2. Catalyst synthesis
N
H
4.2.1.
b-Chloroaldehyde intermediate (a)
The procedure was modified from Benson and Pohland [46].
Phosphorus oxychloride (6.53 g, 42.6 mmol) was added to a flask
containing N,N-dimethylformamide (3.89 g, 53.2 mmol) in an ice
bath and stirred for 7 min. The ice bath was replaced with an
ambient temperature water bath and stirred for an additional
8 min. The mixture was cooled to 0 ꢀC and cyclohexanone (2.61 g,
Conditions: 0.32 mmol diene, 0.32 mmol amine, 5 mol% [(3IPAr)Pd(allyl)]OTf,
a
0.5 mL C6D6, 60 ꢀC, 24 h, sealed NMR tube.
Conversion determined by 1H NMR spectroscopy.
Number in parenthesis represents conversion after 72 h; percentage continues
b
c
to increase with longer reaction times.

184
G. Kuchenbeiser et al. / Journal of Organometallic Chemistry 696 (2011) 179e187
26.6 mmol) was added and stirred for 15 min. The ice bath was
replaced with an ambient temperature water bath and stirred for
an additional 15 min. The orange solution was poured into an
Erlenmeyer flask containing ice (150 g) and made basic by addition
of sodium bicarbonate. After extraction with diethyl ether
(3 ꢂ 100 mL), the combined organic extracts were washed with
100 mL of a saturated aqueous sodium bicarbonate solution,100 mL
of brine, and water (3 ꢂ 100 mL). The organic layer was dried with
magnesium sulfate for 20 min, filtered, and the volatiles removed in
vacuo to yield a red liquid, which was used without further puri-
chloride (10 mL) were combined and allowed to stir at ambient
temperature for 12 h. Solvent was removed in vacuo yielding
a sticky orange solid which was triturated with pentane (2 ꢂ 5 mL)
and washed with diethyl ether (2 ꢂ 10 mL). The solid was extracted
with methylene chloride and precipitated using diethyl ether at
ꢁ25 ꢀC as a yellow powder (0.302 g, 60.0%). Single crystals suitable
for an X-ray diffraction study were grown by slow evaporation of
a concentrated chloroform solution; mp 194e196 ꢀC; 1H NMR
d
¼ 7.73 (dd, 3JPH ¼ 11.4 Hz, 3JHH ¼ 7.8 Hz, 4H), 7.56 (t, 3JHH ¼ 7.2 Hz,
3
3
2H), 7.48 (pseudo t, JHH ¼ 7.8 Hz, JHH ¼ 7.2 Hz, 4H), 7.46 (s, 1H),
fication (3.47 g, 90.2%); 1H NMR
2.29e2.26 (m, 2H), 1.78e1.74 (m, 2H), 1.67e1.63 (m, 2H); 13C{1H}
NMR
d
¼ 10.19 (s,1H), 2.59e2.56 (m, 2H),
7.04 (t, 3JHH ¼ 7.8 Hz, 1H), 6.98 (d, 3JHH ¼ 7.8 Hz, 2H), 2.58e2.56 (m,
2H), 2.10 (s, 6H),1.90e1.88 (m, 2H),1.84e1.81 (m, 2H),1.73e1.70 (m,
3
d
¼ 191.5, 151.7, 133.7, 36.1, 24.0, 23.4, 21.3; IR(neat) 3330 (w),
2H); 13C{1H} NMR
d
¼ 165.0 (d, JPC ¼ 15.3 Hz), 151.7, 145.9
2932 (s), 2848 (m), 2744 (w), 2660 (w), 2356 (w), 2324 (w),
1675 (s), 1618 (s), 1450 (w), 1434 (m), 1345 (m), 1266 (w), 1214
(s), 1172 (w), 1135 (w), 1120 (w), 1093 (w), 1067 (w), 989 (s), 962
(w), 894 (w), 868 (w), 821 (m), 711 (m), 669 (w), 564 (m).
(d, 2JPC ¼ 12.9 Hz), 133.7 (d, 2JPC ¼ 10.8 Hz), 132.2 (d, 4JPC ¼ 2.8 Hz),
131.5 (d, 1JPC ¼ 37.2 Hz), 130.2, 129.3 (d, 3JPC ¼ 11.7 Hz), 128.4, 127.4,
1
2
126.5 (d, JPC ¼ 59.2 Hz), 32.8 (d, JPC ¼ 9.8 Hz), 30.4, 22.5 (d,
3JPC ¼ 4.2 Hz), 21.6, 19.4; 31P{1H}
d
¼ 30.3; IR(nujol) 2955 (s), 2904
(s), 2862 (s), 2727 (w), 2664 (w), 1626 (w), 1580 (w), 1455 (s), 1372
(s), 1305 (w), 1258 (w), 1186 (w), 1144 (w), 1113 (m), 1092 (m), 1025
(w), 993 (w), 962 (w), 921 (w), 885 (w), 802 (w), 770 (m), 744 (m),
718 (m), 693 (m), 662 (m); Anal. Calcd for C27H28Cl2NPPd$2.5
CH2Cl2: C, 45.01; H, 4.23; N, 1.78. Found: C, 45.13; H, 4.06; N, 1.94.
4.2.2.
b-Chloroimine intermediate (b)
b-Chloroaldehyde a (2.166 g, 14.98 mmol) was dissolved in
diethyl ether (20 mL) and cooled to 0 ꢀC for 10 min. Activated 4 Å
molecular sieves were added, followed by (2,6-Me2C6H3)NH2
(2.000 g, 16.50 mmol) diluted with diethyl ether (10 mL). The
resulting solution slowly warmed to ambient temperature with
stirring for 14 h. The solution was passed through a pad of CeliteÒ
and volatiles removed in vacuo to constant weight to yield a red
4.2.5. (3IPAr)Pd(allyl)Cl
In the glovebox, Schlenk flasks were charged separately with
3IPAr (767 mg, 1.93 mmol) and [Pd(allyl)Cl]2 (366 mg, 1.00 mmol).
At room temperature, methylene chloride (10 mL) was added to
each flask and the 3IPAr solution slowly cannulated into the Pd
suspension and stirred overnight. The deep orange solution was
filtered, solvent removed in vacuo, and the resulting yellow solid
liquid, which was used without further purification (3.56 g, 95.9%);
3
1H NMR
d
¼ 8.44 (s, 1H), 7.04 (d, JHH ¼ 7.2 Hz, 2H), 6.92
3
(t, JHH ¼ 7.2 Hz, 1H), 2.62e2.59 (m, 2H), 2.58e2.55 (m, 2H), 2.10
(s, 6H),1.85e1.81 (m, 2H),1.78e1.74 (m, 2H); 13C{1H} NMR
d
¼ 161.8,
151.7, 142.6, 131.8, 128.2, 127.1, 123.8, 35.6, 25.8, 23.8, 21.8, 18.6; IR
(neat) 3288 (w), 3007 (w), 2932 (s), 2858 (m), 2728 (w), 2356 (w),
2328 (w), 1918 (w), 1848 (w), 1690 (m), 1616 (s), 1588 (m), 1527 (w),
1472 (s), 1379 (w), 1355 (w), 1318 (w), 1272 (w), 1230 (m), 1193 (m),
1165 (w), 1128 (w), 1086 (m), 1035 (w), 988 (m), 914 (w), 895
(w), 877 (w), 844 (w), 825 (m), 765 (s), 732 (w), 719 (m), 663 (m).
washed with pentane (2 ꢂ 10 mL) to give a yellow powder (1.06 g,
4
94.6%); mp 84e87 ꢀC; 1H NMR
d
¼ 8.81 (d, JPH ¼ 3.6 Hz, 1H),
3
7.65e7.60 (m, 4H), 7.43e7.37 (m, 6H), 6.89 (d, JHH ¼ 7.2 Hz, 2H),
6.82 (t, 3JHH ¼ 7.2 Hz,1H), 5.10 (pent, 3JHH ¼ 10.2 Hz,1H), 4.22 (v br s,
1H), 3.38 (v br s, 1H), 2.82 (v br s, 2H), 2.79e2.75 (m, 2H), 1.90e1.85
(m, 2H), 1.88 (s, 6H), 1.77e1.73 (m, 2H), 1.67e1.63 (m, 2H); 13C{1H}
1
NMR
d
¼
171.1, 162.8 (d, JPC
¼
25.5 Hz), 152.0, 145.4
4.2.3. 3IPAr
(d, 2JPC ¼ 6.2 Hz), 138.8 (d, 1JPC ¼ 28.4 Hz), 134.3 (d, 3JCP ¼ 12.7 Hz),
2
In the glovebox, two Schlenk tubes were charged with
130.8, 128.9 (d, JPC
¼
10.3 Hz), 127.9, 126.8, 124.0, 118.0
b-chloroimine b (0.372 g, 1.50 mmol) and lithium diphenylphos-
(d, 2JCP ¼ 5.6 Hz), 78.8 (v br), 60.4 (v br), 32.2, 27.0 (d, 2JPC ¼ 8.7 Hz),
3
phide (0.346 g, 1.80 mmol). Toluene (30 mL) was added to each
Schlenk tube and cooled to ꢁ78 ꢀC for 10 min. The imine solution
was added to the phosphide suspension and stirred for 14 h, slowly
warming to ambient temperature. Volatiles were removed in vacuo
and the crude product triturated with pentane (10 mL). The product
was extracted with pentane (3 ꢂ 25 mL), filtered and dried in vacuo
23.2 (d, JPC ¼ 5.3 Hz), 21.6, 18.4; 31P{1H} NMR
d
¼ 19.1; IR(nujol)
3052 (w), 2925 (s), 2850 (s), 1613 (s), 1591 (m), 1464 (s), 1427 (s),
1375 (m), 1263 (w), 1196 (m), 1092 (s), 1017 (w), 846 (w), 801 (w),
749 (s), 697 (s); HRMScalc: 544.1385 for C30H33NPPdþ [M ꢁ Clꢁ]þ;
HRMSmeas: 544.1375.
to give an off-white foamy solid (0.523 g, 87.7%); 1H NMR
d
¼ 9.05
4.2.6. [(3IPAr)Pd(allyl)]OTf
(d, 4JPH ¼ 9.0 Hz, 1H), 7.35e7.32 (m, 10H), 6.98 (d, 3JHH ¼ 7.2 Hz, 2H),
6.88 (t, 3JHH ¼ 7.2 Hz,1H), 2.78e2.75 (m, 2H),1.99e1.96 (m, 2H),1.97
(s, 6H), 1.77e1.73 (m, 2H), 1.68e1.65 (m, 2H); 13C{1H} NMR
In the glovebox, a Schlenk flask was charged with (3IPAr)Pd
(allyl)Cl (565 mg, 0.973 mmol) and silver triflate (257 mg,
1.00 mmol). In the absence of light, methylene chloride (15 mL)
was added and the resulting suspension stirred at room tempera-
ture overnight. The reaction mixture was filtered to give a yellow/
orange solution. Solvent was removed in vacuo and the resulting
yellow solid washed with pentane (2 ꢂ 10 mL) to afford a micro-
crystalline yellow solid (593 mg, 87.9%); mp 103e107 ꢀC; 1H NMR
3
2
d
¼ 163.0 (d, JPC ¼ 41.2 Hz), 151.7, 147.3 (d, JPC ¼ 18.2 Hz), 145.3
(d, 1JPC ¼ 23.0 Hz), 136.3 (d, 1JPC ¼ 11.1 Hz), 133.5 (d, 2JPC ¼ 19.0 Hz),
3
128.8 (d, JPC
¼
4.5 Hz), 128.7, 128.1, 127.3, 123.6, 30.7
(d, JPC ¼ 4.0 Hz), 26.6 (d, JPC ¼ 5.7 Hz), 23.6, 22.2, 18.5; 31P{1H}
3
2
NMR
d
¼ ꢁ12.6; IR(nujol) 3068 (m), 3057 (m), 3016 (w), 2933 (m),
2860 (m), 2736 (w), 2674 (w), 2362 (w), 2279 (w), 1953 (w), 1880
(w), 1813 (w), 1776 (w), 1750 (w), 1657 (w), 1615 (s), 1589 (m), 1475
(m), 1434 (s), 1372 (w), 1351 (w), 1325 (w), 1304 (w), 1257 (m), 1221
(w), 1190 (m), 1159 (w), 1091 (s), 1065 (m), 1024 (s), 915 (w), 889
(w), 842 (m), 801 (s), 764 (m), 744 (s), 723 (m), 697 (s), 601 (w);
HRMScalc: 398.2038 for C27H29NP [M þ H]þ; HRMSmeas: 398.2041.
[47]
d
¼ 7.70 (s, 1H), 7.60e7.48 (m, 8H), 7.46e7.41 (m, 2H), 7.12
(broad s, 3H), 5.78e5.71 (m,1H), 3.58 (t, 3JPH ¼ 6.6 Hz, 3JHH ¼ 6.6 Hz,
3
3
1H), 3.50 (dd, JPH
¼
14.4 Hz, JHH
¼
9.6 Hz, 1H), 3.43
3
3
(d, JHH ¼ 6.6 Hz, 1H), 2.76 (d, JHH ¼ 12.6 Hz, 1H), 2.73e2.62
(m, 2H), 2.06 (s, 3H), 2.04e2.02 (m, 1H), 1.99e1.97 (m, 1H), 1.95 (s,
3H), 1.87e1.83 (m, 1H), 1.81e1.78 (m, 1H), 1.77e1.71 (m, 2H); 13C
{1H} NMR [47]
d
¼ 168.0 (d, JPC ¼ 10.8 Hz), 154.9, 146.2
3
4.2.4. (3IPAr)PdCl2
(d, JPC ¼ 12.4 Hz), 133.2 (d, JPC ¼ 13.3 Hz), 133.0, 132.9
2
2
2
4
4
A slurry of palladium(II) chloride (0.155 g, 0.876 mmol) in
(d, JPC ¼ 13.0 Hz), 132.2 (d, JPC ¼ 2.1 Hz), 132.1 (d, JPC ¼ 2.1 Hz),
3 3
acetonitrile (30 mL) and 3IPAr (0.383 g, 0.964 mmol) in methylene
130.0 (d, JPC ¼ 10.9 Hz), 129.9 (d, JPC ¼ 10.9 Hz), 128.9 (d,

G. Kuchenbeiser et al. / Journal of Organometallic Chemistry 696 (2011) 179e187
185
1JPC ¼ 19.6 Hz), 128.3 (d, 1JPC ¼ 48.0 Hz), 127.8 (d, 1JPC ¼ 46.3 Hz),
4.3.2.5. N-(3-Methyl-2-buten-1-yl)-N-methyl-n-butylamine (2h). 1H
2
2
127.3, 126.9, 123.6 (d, JPC ¼ 6.0 Hz), 84.5 (d, JPC ¼ 28.8 Hz), 55.8
NMR
d
¼ 5.30 (t, 3JHH ¼ 6.6 Hz, 1H), 2.96 (d, 3JHH ¼ 6.6 Hz, 2H), 2.35
(d, 2JPC ¼ 4.4 Hz), 33.7 (d, 3JPC ¼ 10.3 Hz), 30.1, 22.3 (d, 3JPC ¼ 4.1 Hz),
(t, 3JHH ¼ 7.2 Hz, 2H), 2.22 (s, 3H), 1.77 (s, 3H), 1.68 (s, 3H), 1.43e1.26
2
3
21.6, 18.5 (d, JPC ¼ 20.1 Hz); 31P{1H} NMR
d
¼ 25.2; 19F NMR
(m, 2H), 1.36 (m, 2H), 0.96 (t, JHH ¼ 7.2 Hz, 3H); 13C{1H} NMR
d
¼ ꢁ78.3; IR(nujol) 3050 (w), 2926 (s), 2852 (s), 2727 (w), 2678
d
¼ 134.6, 122.0, 57.4, 55.5, 42.2, 29.8, 26.0, 20.9, 18.0, 14.2;
(w), 2293 (w), 1976 (w), 1908 (w), 1834 (w), 1629 (m), 1579 (m),
1461 (s), 1437 (s), 1381 (m), 1269 (s), 1225 (s), 1194 (m), 1145 (s),
1095 (s), 1064 (m), 1027 (s), 909 (m), 779 (s), 754 (s), 698 (s), 636
HRMScalc: 156.1752 for C10H22N [M þ H]þ; HRMSmeas: 156.1754.
4.3.2.6. N-(3-Methyl-2-buten-1-yl)-2-methylindoline (2l). 1H NMR
(s); HRMScalc
:
544.1385 for C30H33NPPdþ [M]þ; HRMSmeas
:
(C6D6)
d
¼ 7.14 (t, 3JHH ¼ 7.2 Hz, 1H), 7.03 (d, 3JHH ¼ 7.2 Hz, 1H), 6.76
544.1375; Anal. Calcd. for C31H33F3NO3PPdS$½ CH2Cl2: C, 51.37; H,
4.65; N, 1.90. Found: C, 51.36; H, 4.30; N, 1.99.
(t, 3JHH ¼ 7.2 Hz, 1H), 6.51 (d, 3JHH ¼ 7.2 Hz, 1H), 5.29e5.25 (m, 1H),
3.66 (dd, 2JHH ¼ 16.2 Hz, 3JHH ¼ 4.2 Hz, 1H), 3.59 (dd, 2JHH ¼ 16.2 Hz,
3JHH ¼ 7.8 Hz, 1H), 3.53e3.45 (m, 1H), 2.84 (dd, JHH ¼ 15.0 Hz,
2
3JHH ¼ 8.4 Hz, 1H), 2.42 (dd, 2JHH ¼ 15.0 Hz, 3JHH ¼ 10.2 Hz, 1H), 1.54
4.3. Catalysis
(s, 3H), 1.51 (s, 3H), 1.09 (d, 3JHH ¼ 6.0 Hz, 3H); 13C{1H} NMR (C6D6)
d
¼ 153.0, 134.0, 129.3, 127.8, 124.5, 121.4, 117.9, 107.6, 59.5, 43.9,
4.3.1. General procedure for the Pd catalyzed hydroamination of
dienes
37.6, 25.7, 19.3, 17.9; HRMScalc: 202.1596 for C14H20N [M þ H]þ;
HRMSmeas: 202.1590.
All manipulations were performed in an inert atmosphere glo-
vebox (N2). The Pd catalyst (10.2 mg, 0.0147 mmol,e5 mol%), C6D6
(0.5 mL), amine (0.32 mmol), and lastly diene (0.32 mmol) were
added to a J-Young NMR tube that was subsequently sealed. Upon
addition of the amine, the pale yellow suspension rapidly turned to
a deep red solution. The reaction progress was monitored by 1H
NMR until completion, as assessed by the complete disappearance
of diene. Product allyl amines were isolated as follows: the crude
reaction mixture was loaded onto a short column of Al2O3 (0.5
inches) and eluted with toluene. The product band was subse-
quently reduced under rotary evaporation at 35 ꢀC to constant
mass. Representative examples: 2a (45 mg isolated; 91%); 3a
(39 mg isolated; 72%).
4.3.3. 1,3-Diene addition products
N-(2,3-Dimethyl-2-buten-1-yl)-piperidine (3d) [49] and N-(2,3-
dimethyl-2-buten-1-yl)-diethylamine (3f) [49] were identified by
comparison to published NMR data. Compounds listed below with
references represent previously reported species with no spectral
data or from difficult to access journals.
4.3.3.1. N-(2,3-Dimethyl-2-buten-1-yl)-morpholine (3a) [52]. 1H
3
NMR (C6D6)
d
¼ 3.55 (t, JHH ¼ 4.4 Hz, 4H), 2.73 (s, 2H), 2.15 (t,
3JHH ¼ 4.4 Hz, 4H), 1.69 (s, 3H), 1.56 (broad s, 6H); 13C{1H} NMR
(C6D6)
d
¼ 128.9, 125.5, 67.7, 61.9, 54.3, 21.4, 20.7, 18.1.
4.3.3.2. N-(2,3-Dimethyl-2-buten-1-yl),N0-methyl-piperazine (3b). 1H
NMR
¼ 2.86 (s, 2H), 2.61e2.15 (broad s, 8H), 2.23 (s, 3H), 1.66e1.62
4.3.2. 1,2-Diene addition products
d
N-(3-Methyl-2-buten-1-yl)-morpholine (2a) [33,48], N-(3-methyl-
2-buten-1-yl)-piperidine (2d) [48], N-(3-methyl-2-buten-1-yl)-dieth-
ylamine (2f) [33,49], N-(3-methyl-2-buten-1-yl)-dibenzylamine
(2i) [33], N-(3-methyl-2-buten-1-yl)-1,2,3,4-tetrahydroisoquinoline
(2j) [33,48], N-(3-methyl-2-buten-1-yl)-indoline (2k) [33] and N-(3-
methyl-2-buten-1-yl)-1,2,3,4-tetrahydroquinoline (2m) [33], were
identified by comparison to published NMR data. Compounds listed
below with references represent previously reported species with no
spectral data or from difficult to access journals.
(overlapping s, 9H); 13C{1H} NMR
d
¼ 128.5, 125.0, 61.0, 55.5, 53.1,
46.2, 21.1, 20.4, 17.8; HRMScalc: 183.1861 for C11H23N2 [M þ H]þ;
HRMSmeas: 183.1869.
4.3.3.3. N-(2,3-Dimethyl-2-buten-1-yl)-thiomorpholine
NMR
¼ 2.89 (s, 2H), 2.64e2.58 (m, 8H), 1.67 (s, 3H), 1.66 (s, 3H),
(3c). 1H
d
1.65 (s, 3H); 13C{1H} NMR
d
¼ 128.9, 124.9, 61.8, 54.9, 28.4, 21.2,
20.4, 17.6; HRMScalc: 186.1316 for C10H20NS [M þ H]þ; HRMSmeas
:
186.1323.
4.3.2.1. N-(3-Methyl-2-buten-1-yl),N0-methyl-piperazine
(2b). 1H
¼ 5.07 (t, JHH ¼ 7.2 Hz, 1H), 2.76 (d, JHH ¼ 7.2 Hz, 2H),
2.28e2.24 (broad m, 8H), 2.09 (s, 3H), 1.54 (s, 3H), 1.45 (s, 3H); 13C
4.3.3.4. N-(2,3-Dimethyl-2-buten-1-yl)-pyrrolidine (3e). 1H NMR
¼ 3.03 (s, 2H), 2.46e2.42 (m, 4H), 1.76e1.66 (m, 10H), 1.66 (s, 3H);
3
3
NMR
d
d
13C{1H} NMR
d
¼ 128.4, 126.3, 58.9, 54.4, 23.7, 21.1, 20.5, 18.1;
{1H} NMR
d
¼ 134.9, 120.8, 55.8, 55.0, 52.9, 45.8, 25.7, 17.8;
HRMScalc: 154.1596 for C10H20N [M þ H]þ; HRMSmeas: 154.1592.
HRMScalc: 169.1705 for C10H21N2 [M þ H]þ; HRMSmeas: 169.1707.
4.3.3.5. N-(2,3-Dimethyl-2-buten-1-yl)-di-n-butylamine
(3g). 1H
¼ 2.89 (s, 2H), 2.29 (t, JHH ¼ 7.2 Hz, 4H), 1.68 (s, 3H), 1.66
4.3.2.2. N-(3-Methyl-2-buten-1-yl)-thiomorpholine (2c). 1H NMR
NMR
d
3
3
3
(C6D6)
d
¼ 5.21 (t, JHH ¼ 7.2 Hz, 1H), 2.74 (d, JHH ¼ 7.2 Hz, 2H),
(broad s, 6H), 1.43e1.33 (m, 4H), 1.32e1.23 (m, 4H), 0.88 (t,
2.45e2.37 (broad m, 8H), 1.55 (s, 3H), 1.41 (s, 3H); 13C{1H} NMR
3JHH ¼ 7.2 Hz, 6H); 13C{1H} NMR
d
¼ 127.2, 126.8, 57.1, 53.6, 29.5,
(C6D6)
d
¼ 135.2, 122.6, 57.6, 55.6, 28.8, 26.3, 18.4; HRMScalc
:
21.2, 20.9, 20.4, 17.6, 14.3; HRMScalc: 212.2378 for C14H30N
172.1160 for C9H18NS [M þ H]þ; HRMSmeas: 172.1165.
[M þ H]þ; HRMSmeas: 212.2373.
4.3.2.3. N-(3-Methyl-2-buten-1-yl)-pyrrolidine (2e) [50]. 1H NMR
4.3.3.6. N-(2,3-Dimethyl-2-buten-1-yl)-1,2,3,4-tetrahydroisoquinoline
(3j). 1H NMR
¼ 7.16e7.12 (m, 3H). 7.07e7.03 (m, 1H), 3.61 (s, 2H),
3.13, (s, 2H), 2.91 (t, JHH ¼ 4.8 Hz, 2H), 2.69 (t, JHH ¼ 4.8 Hz, 2H),
1.79 (broad s, 6H), 1.77 (s, 3H); 13C{1H} NMR
d
¼ 5.28 (t, 3JHH ¼ 6.8 Hz, 1H), 3.03 (d, 3JHH ¼ 6.8 Hz, 2H), 2.49e2.35
d
(m, 4H), 1.85e1.64 (m, 4H), 1.69 (s, 3H), 1.62 (s, 3H); 13C{1H} NMR
3
3
d
¼ 134.1, 122.2, 54.2, 53.7, 26.1, 23.6, 18.2.
d
¼ 135.6, 134.9, 128.8,
128.6,126.8,126.1,125.6,125.3, 60.9, 56.4, 50.4, 29.5, 21.2, 20.5,17.8;
4.3.2.4. N-(3-Methyl-2-buten-1-yl)-di-n-butylamine (2g) [51]. 1H
HRMScalc: 216.1752 for C15H22N [M þ H]þ; HRMSmeas: 216.1759.
NMR
d
¼ 5.22 (t, 3JHH ¼ 6.8 Hz, 1H), 3.00 (d, 3JHH ¼ 6.8 Hz, 2H), 2.36
(m, 4H), 1.70 (s, 3H), 1.61 (s, 3H), 1.44e1.38 (m, 4H), 1.33e1.22 (m,
4.3.3.7. N-(2,3-Dimethyl-2-buten-1-yl)-indoline
(3k). 1H
NMR
4H), 0.88 (t, 3JHH ¼ 7.6 Hz, 6H); 13C{1H} NMR
d
¼ 134.1, 122.3, 53.8,
d
¼ 7.15e7.06 (m, 2H), 6.71e6.66 (m,1H), 6.60e6.54 (m,1H), 3.69 (s,
3
3
51.9, 29.5, 26.1, 21.0, 18.2, 14.3; HRMScalc: 198.2222 for C13H28
N
2H), 3.28 (t, JHH ¼ 8.4 Hz, 2H), 2.97 (t, JHH ¼ 8.4 Hz, 2H), 1.83 (s,
[M þ H]þ; HRMSmeas: 198.2227.
3H), 1.79 (broad s, 6H); 13C{1H} NMR
d
¼ 153.4, 130.3, 127.5, 124.5,

186
G. Kuchenbeiser et al. / Journal of Organometallic Chemistry 696 (2011) 179e187
4.4.2. [(3IPAr)Pd(allyl)]OTf
Table 6
Crystal data and collection parameters.
X-ray quality crystals were grown by slow diffusion of pentane
Compound
(3IPAr)PdCl2
[(3IPAr)Pd(allyl)]OTf
into a THF solution of the complex at ambient temperature. In the
final model, the allyl group was found to be disordered in a 4:1 ratio
of cis and trans isomers, while the 3- and 4-carbons of the cyclo-
hexenyl unit were disordered in a 1:1 ratio of two boat-like
conformations. The final cycle of full-matrix least-squares refine-
ment was based on 8986 observed reflections and 428 variable
parameters and converged yielding final residuals: R ¼ 0.0411,
Rall ¼ 0.0453, and GOF ¼ 1.018.
Formula
Fw
space group
temperature (K)
a (Å)
C
27H28Cl2NPPd$2 CHCl3
C31H33F3NO3PPdS$½ C4H8O
730.07
C2/c (#15)
140(2)
36.441(2)
8.9994(5)
20.505(1)
90.000
103.822(1)
90.000
813.51
P212121 (#19)
150(2)
11.3505(8)
14.518(1)
20.324(1)
90.000
90.000
90.000
3349.1(4)
4
1.613
b (Å)
c (Å)
a
b
g
(deg)
(deg)
(deg)
V (Å3)
6529.7(6)
8
1.485
Acknowledgements
Z
densitycalc (g/cm3)
Diffractometer
Radiation
This material is based upon work supported by the National
Science Foundation under CHE-0841611.
Siemens SMART
Siemens SMART
Mo Ka
Graphite
CCD area detector
, 0.3ꢀ
(
l
¼ 0.71073 Å)
Mo Ka
Graphite
CCD area detector
, 0.3ꢀ
(l
¼ 0.71073 Å)
Monochromator
Detector
scan type, width
scan speed
no. of reflns measd
2q range (deg)
cryst dimens (mm)
no. of reflns measd
no. of unique reflns
no. of obs.
Appendix A. Supplementary material
u
u
20 s/frame
Hemisphere
3.44e66.78
0.28 ꢂ 0.16 ꢂ 0.10
47874
20 s/frame
Hemisphere
2.30e61.22
0.28 ꢂ 0.22 ꢂ 0.10
41520
CCDC 783884 ((3IPAr)PdCl2) and CCDC 783885 ([(3IPAr)Pd
(allyl)]OTf) contain the supplementary crystallographic data for
this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
12106
10027
(I > 2
s
(I))
10783
8986
Rint
0.0661
361
0.0756, 0.1334, 0.0881
1.193
0.0388
428
0.0411, 0.1104, 0.0453
1.018
References
no. of params
R, Rw, Rall
GOF
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