Preparation of half-sandwich alkyl-titanium(IV) complexes stabilized by a cyclopentadienyl ligand with a pendant phosphine tether and their use in the catalytic hydroamination of aliphatic and aromatic alkynes

Article abstract of DOI:10.1021/om060370h

Complex Cp^PTiCl₃ (1; Cp^P = C ₅H₄CH₂CH₂PPh₂) reacts with 3.0, 2.0, and 1.0 equiv of MeMgCl to give Cp_PTiMe₃ (2), Cp_PTiMe₂Cl (3), and Cp^PTiMeCl₂ (4). In solution the P-donor substituent of the cyclopentadienyl ligand is involved in a coordination-dissociation equilibrium (ΔH° = 7.7 ± 0.1 kcal·mor^-1 and ΔS° = 36.9 ± 0.4 cal·mol^-1·K^-1 for 2, ΔH° = 6.0 ± 0.2 kcal·mol^-1 and ΔS° = 22.3 ± 0.6 cal·mol^-1·K^-1 for 3, and ΔH° = 6. 1 · 0.2 kcal·mol^-1 and ΔS° = 24.4 ± 1 cal±mo^-1·K^-1 for 4). The reaction of 1 with 3.0 equiv of PhCH₂MgCl affords Cp_PTi(CH ₂Ph)₃ (5), containing a free phosphine pendant group between -90 and 20°C. In contrast to 5, the PPh₂ group of {(2,6-ⁱPr₂C₆H₃)NH}Cp ^PTi{=N(2,6-ⁱPr₂C₆H₃)} (7), which is formed from the reaction of 2 with 2,6-diisopropylaniline, remains coordinated to the titanium atom between 60 and -60°C. Complex 2 is an efficient catalyst precursor for the regioselective- hydroamination of aliphatic (1-octyne and cyclohexylacetylene) and aromatic (phenylacetylene and 1-phenylpropyne) alkynes with aromatic (2,6-dimethylaniline and 2,6-diisopropylaniline) and aliphatic (tert-butylamine, dodecylamine, and cyclohexylamine) amines. The reactions give imines or imine-enamine mixtures, which are reduced to the corresponding secondary amines. The Markovnikov or anti-Markovnikov nature of the obtained products depends on the aliphatic or aromatic character of both the alkyne and the amine. Markovnikov products with regioselectivities of 100% are formed from the reactions between aliphatic alkynes and aromatic amines, while anti-Markovnikov derivatives with regioselectivies of 100% are obtained from the reactions of aromatic alkynes with all the studied amines and from the reactions of the aliphatic alkynes with tert-butylamine and dodecylamine. The reaction of 1-octyne and cyclohexylacetylene with cyclohexylamine gives mixtures of both types of products. Some considerations about the mechanism of the catalysis are also presented.

Full text of DOI:10.1021/om060370h

Organometallics 2006, 25, 4079-4089
4079
Preparation of Half-Sandwich Alkyl-Titanium(IV) Complexes
Stabilized by a Cyclopentadienyl Ligand with a Pendant Phosphine
Tether and Their Use in the Catalytic Hydroamination of Aliphatic
and Aromatic Alkynes
Mar´ıa L. Buil, Miguel A. Esteruelas,* Ana M. Lo´pez,* and A. Concepcio´n Mateo
Departamento de Qu´ımica Inorga´nica, Instituto de Ciencia de Materiales de Arago´n, UniVersidad de
Zaragoza-CSIC, 50009 Zaragoza, Spain
ReceiVed April 28, 2006
Complex CpPTiCl3 (1; CpP ) C5H4CH2CH2PPh2) reacts with 3.0, 2.0, and 1.0 equiv of MeMgCl to
give CpPTiMe3 (2), CpPTiMe2Cl (3), and CpPTiMeCl2 (4). In solution the P-donor substituent of the
cyclopentadienyl ligand is involved in a coordination-dissociation equilibrium (∆H° ) 7.7 ( 0.1
kcal‚mol-1 and ∆S° ) 36.9 ( 0.4 cal‚mol-1‚K-1 for 2, ∆H° ) 6.0 ( 0.2 kcal‚mol-1 and ∆S° ) 22.3 (
0.6 cal‚mol-1‚K-1 for 3, and ∆H° ) 6.1 ( 0.2 kcal‚mol-1 and ∆S° ) 24.4 ( 1 cal‚mol-1‚K-1 for 4).
The reaction of 1 with 3.0 equiv of PhCH2MgCl affords CpPTi(CH2Ph)3 (5), containing a free phosphine
pendant group between -90 and 20 °C. In contrast to 5, the PPh2 group of {(2,6-iPr2C6H3)NH}CpPTi-
{dN(2,6-iPr2C6H3)} (7), which is formed from the reaction of 2 with 2,6-diisopropylaniline, remains
coordinated to the titanium atom between 60 and -60 °C. Complex 2 is an efficient catalyst precursor
for the regioselective hydroamination of aliphatic (1-octyne and cyclohexylacetylene) and aromatic
(phenylacetylene and 1-phenylpropyne) alkynes with aromatic (2,6-dimethylaniline and 2,6-diisopropyl-
aniline) and aliphatic (tert-butylamine, dodecylamine, and cyclohexylamine) amines. The reactions give
imines or imine-enamine mixtures, which are reduced to the corresponding secondary amines. The
Markovnikov or anti-Markovnikov nature of the obtained products depends on the aliphatic or aromatic
character of both the alkyne and the amine. Markovnikov products with regioselectivities of 100% are
formed from the reactions between aliphatic alkynes and aromatic amines, while anti-Markovnikov
derivatives with regioselectivies of 100% are obtained from the reactions of aromatic alkynes with all
the studied amines and from the reactions of the aliphatic alkynes with tert-butylamine and dodecylamine.
The reaction of 1-octyne and cyclohexylacetylene with cyclohexylamine gives mixtures of both types of
products. Some considerations about the mechanism of the catalysis are also presented.
half-sandwich titanium examples previously reported are the
Introduction
trichloro derivatives CpPTiCl3 (CpP ) C5H4CH2CH2PPh2)5 and
The search for the highest selectivity in the organic trans-
formations mediated by transition metal complexes is one of
the driving forces of modern organometallic chemistry.
Half-sandwich titanium complexes with constrained geom-
etry, including phosphido derivatives,1 have received great
attention as a consequence of their catalytic properties, in
particular for olefin polymerization.2 In contrast, complexes
containing a cyclopentadienyl ligand with a two-electron-donor
pendant group have been scarcely studied.3 Those with a PR2
function are particularly rare.4 As far as we know, the unique
(C5H4CMe2PHtBu)TiCl3 and the trialkoxide CpPTi(OBu)3.7
6
Transition metal complexes with cyclopentadienyl ligands
bearing two-electron-donor substituents are an option with a
promising future for some reactions. Their potential stems from
the reversible coordination of the pendant function, which
stabilizes highly reactive electrophilic metal centers until the
substrate coordination.8
As a part of our work on transition metal complexes con-
taining a cyclopentadienyl ligand with a pendant donor group,9
we have recently reported that complexes CpNTiCl3 (CpN )
10
* To whom correspondence should be addressed. E-mail: maester@
posta.unizar.es; amlopez@unizar.es.
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10.1021/om060370h CCC: $33.50 © 2006 American Chemical Society
Publication on Web 07/11/2006

4080 Organometallics, Vol. 25, No. 17, 2006
Buil et al.
C5H4CH2CH2NMe2) and CpOTiCl3 (CpO ) C5H4CH2CH2-
for the reaction of diphenylacetylene and 2,6-dimethyl-
aniline.14 Doye and co-workers have described the hydroami-
nation of various internal alkynes by using Cp2TiMe2 and Ind2-
TiMe2.15 Odom and co-workers have demonstrated that titanium
amido complexes, such as Ti(NMe2)4 and Ti(NMe2)(dpma)
(dpma ) di(pyrrolyl-R-methyl)methylamine), are effective pre-
catalysts for the hydroamination of terminal alkynes to form
Markovnikov imines.16
11
OMe) react with 1.0, 2.0, and 3.0 equiv of MeMgCl to afford
the mono-, di-, and trimethyl derivatives CpNTiMeCl2 and CpO-
TiMeCl2, CpNTiMe2Cl and CpOTiMe2Cl, and CpNTiMe3 and
CpOTiMe3, respectively. The trimethyl compounds are efficient
catalyst precursors for the regioselective anti-Markovnikov
hydroamination of nonsymmetrically substituted aromatic alkynes
with aliphatic and aromatic amines. The pendant group of the
precursors affects significantly their catalytic properties as
compared to those of the parent compound CpTiMe3, which
contains an unsubstituted cyclopentadienyl ligand. Thus, while
the amine derivative is less efficient than CpTiMe3 in all cases,10
the presence of the ether substituent in the cyclopentadienyl
ligand increases the activity of the system for the hydroamination
reactions with cyclohexylamine and 2,6-dimethylaniline.11
Within the transition-metal-catalyzed hydroaminations,12 im-
portant progress in the intermolecular hydroamination of alkynes
with titanium complexes has been reported by the groups of
Beller,13 Bergman,14 Doye,15 Odom,16 and others.17 Beller and
co-workers have found that, among others, titanocene-π-alkyne
complexes of the type Cp2Ti(η2-Me3SiC2R) catalyze the anti-
Markovnikov hydroamination of aliphatic alkynes and phenyl-
acetylene.13 Bergman’s group has developed Cp(ArNH)TidNAr
As a part of our effort to develop effective methods of C-N
bond formation,10,11,18 we have recently studied the catalytic
activity of the novel (2-diphenylphosphinoethyl)cyclopenta-
dienyltitanium complex CpPTiMe3 in the intermolecular hydro-
amination of alkynes. This paper reports (i) the sequential
methylation of CpPTiCl3 until CpPTiMe3, the thermodynamic
parameters for the intramolecular dissociation-coordination
equilibria of the pendant phosphine group of the resulting methyl
derivatives, and their comparison with those of the CpNTiMexCl3-x
and CpOTiMexCl3-x (x ) 1-3) counterparts; (ii) the hydroami-
nation of unsymmetrical aliphatic alkynes in the presence of
CpPTiMe3 and its comparison with the hydroamination catalyzed
by CpTiMe3; (iii) the hydroamination of unsymmetrical aromatic
alkynes in the presence of CpPTiMe3 and its comparison with
the hydroaminations catalyzed by CpOTiMe3 and CpTiMe3; and
(iv) some considerations about the mechanism of the hydroami-
nation of alkynes catalyzed by half-sandwich titanium com-
plexes, containing cyclopentadienyl ligands with a two-electron-
donor ligand, which relate the coordination ability of the pendant
donor group and the activity of the systems.
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Results and Discussion
1. Methylation of CpPTiCl3: Formation and Character-
ization of CpPTiMe3 and Related Compounds. Treatment at
-40 °C of a diethyl ether solution of CpPTiCl3 (1) with 3.0
equiv of MeMgCl in tetrahydrofuran gives rise to the trimethyl
derivative CpPTiMe3 (2), as a result of the replacement of the
three chloride ligands of the starting compound by methyl
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Half-Sandwich Alkyl-Titanium(IV) Complexes
Organometallics, Vol. 25, No. 17, 2006 4081
Figure 1. Temperature-dependent 31P NMR of complexes 2, 3, 4, 5, and 7 in C7D8. (b) Denotes the measured chemical shifts.
groups. Complex 2 is isolated as an analytically pure orange
oil in 48% yield. Under the same conditions, the addition of
2.0 equiv of MeMgCl to 1 produces the selective substitution
of two chloride ligands, to form the dimethyl derivative CpP-
TiMe2Cl (3), which is isolated as an analytically pure red oil in
44% yield. Treatment of 1 with 1.0 equiv of MeMgCl yields
the monomethyl species CpPTiMeCl2 (4), as a consequence of
the selective substitution of one of the chloride ligands of 1 by
a methyl group. Complex 4 is isolated as an orange solid in
31% yield. These methyl compounds are notable because they
are the first half-sandwich alkyltitanium complexes stabilized by
a cyclopentadienyl ligand containing a phosphine pendant group.
In solution the pendant P-donor substituent of the cyclo-
pentadienyl ligand of 2-4 is involved in a coordination-
dissociation process. This is strongly supported by the phosphine
chemical shifts in the 31P{1H} NMR spectra, which are
temperature dependent (Figure 1). In toluene-d8, the chemical
shift of the singlet due to the phosphine group of 2 changes
from -15.4 ppm at 20 °C to 9.2 ppm at -90 °C (∆δ(31P) )
24.6). In the same temperature range, the values of ∆δ(31P) for
3 and 4 are 27.9 and 42.8 ppm, respectively.
and ∆S° ) 24.4 ( 1 cal‚mol-1‚K-1 for 4. The positive values
of ∆S° are in agreement with the free character of the pendant
group in the six-coordinate isomers b, whereas the low values
of ∆H° indicate weak Ti-P bonds in the seven-coordinate
isomers a.
According to the values of ∆H° and ∆S° calculated for 2-4,
the molar fractions of hexacoordinate form b at 20 °C in toluene-
d8 are about 1.0 (2) and between 0.7 and 0.9 (3 and 4). These
values are similar to those of CpOTiMexCl3-x (x ) 1-3) and
significantly higher than those found for CpNTiMexCl3-x (about
0.8 and between 0.3 and 0.4). Their comparison reveals that
the affinity of the amine group of the ligand (2-dimethylamino-
ethyl)cyclopentadienyl toward titanium(IV) is notably higher
than those of the pendant groups of the ligands (2-methoxy-
ethyl)cyclopentadienyl and (2-diphenylphosphinoethyl)cyclo-
pentadienyl.
For the three cyclopentadienyl ligands the molar fraction of
hexacoordinate form b increases as the chlorine atoms at the
metal center are replaced by methyl groups. Although electronic
factors are certainly determinant, this suggests that the steric
hindrance experienced by the pendant group and the monoden-
tate ligands at the metal also has a significant contribution to
the destabilization of the bond between the titanium atom and
the pendant donor group. In fact, the treatment of 1 in diethyl
ether with 3.0 equiv of PhCH2MgCl (bulkier than CH3) affords
the six-coordinate complex CpPTi(CH2Ph)3 (5), containing a free
phosphine pendant group between -90 and 20 °C. This complex
is isolated as an analytically pure red oil in 62% yield.
The free character of the phosphine substituent of the
cyclopentadienyl ligand is strongly supported by the chemical
shift of the singlet observed in the 31P{1H} NMR spectrum of
5 in toluene-d8 at -90 °C (δ, -17.2), which is similar to that
previously reported for (2-diphenylphosphinoethyl)(trimethylsilyl)-
cyclopentadiene (δ, -14.2)8a and not very sensitive to the
temperature (Figure 1).
For the coordination-dissociation processes shown in Figure
1, the equilibrium constants between 20 and -90 °C were
determined according to eq 1.19
δmax - δT
[b]
K )
)
(1)
δT - δmin
[a]
The temperature dependence of the equilibrium gives the val-
ues ∆H° ) 7.7 ( 0.1 kcal‚mol-1 and ∆S° ) 36.9 ( 0.4
cal‚mol-1‚K-1 for 2, ∆H° ) 6.0 ( 0.2 kcal‚mol-1 and ∆S° )
22.3 ( 0.6 cal‚mol-1‚K-1 for 3, and ∆H° ) 6.1 ( 0.2 kcal‚mol-1
(19) Dalling, D. K.; Zilm, K. W.; Grant, D. M.; Heeschen, W. A.; Horton,
W. J.; Pugmire, R. J. J. Am. Chem. Soc. 1981, 103, 4817.

4082 Organometallics, Vol. 25, No. 17, 2006
Buil et al.
Scheme 1
Scheme 2
Scheme 3
2. Hydroamination of Terminal Aliphatic Alkynes. Com-
plex 2 and the parent compound CpTiMe3 (6), which contains
an unsubstituted cyclopentadienyl ligand, are very efficient cata-
lyst precursors for the addition of one of the N-H bonds of
aromatic and aliphatic primary amines to the carbon-carbon
triple bond of alkynes such as 1-octyne and cyclohexylacetylene.
The reactions were performed in toluene at 100 °C, using
5 mol % of catalyst precursor and stoichiometric amounts of
alkyne and amine. In contrast to metallocene precursors,13f,15k
under the used conditions, the loss of alkyne as a consequence
of dimerization or polymerization side-reactions does not take
place.
As can be seen in Table 1, both alkynes react with aromatic
amines, such as 2,6-dimethylaniline and 2,6-diisopropylaniline,
to give enamine-imine mixtures resulting from regioselective
Markovnikov couplings. The mixtures were transformed in
quantitative yield into the corresponding secondary amines, by
reduction with NaCNBH3/p-TsOH in tetrahydrofuran at room
temperature (Scheme 1).
For the reactions shown in Scheme 1, the presence of a
2-diphenylphosphinoethyl substituent at the cyclopentadienyl
ligand certainly increases the efficiency of the half-sandwich
titanium precursor. This is clearly evident when the results of
the hydroamination in the presence of 2 are compared with those
in the presence of 6 (Table 1). With the first precursor (entries
1, 3, 5, and 7) the quantitative conversion of the alkynes into
the hydroamination products occurs within a short time (0.75-
1.5 h), while with 6 as a catalyst precursor (entries 2, 4, 6, and
8) high conversions are achieved only after longer times (6-
24 h). From the regioselectivity point of view, the quantitative
transformation of the alkynes into Markovnikov products is also
remarkable. In this context, it should be mentioned that for the
reaction of 1-octyne and 2,6-dimethylaniline both catalyst
precursors are even more regioselective than the metallocenes
Cp2Ti(η2-Me3SiC2SiMe3) and CpEt2Ti(η2-Me3SiC2SiMe3).13f
In contrast to the anilines, tert-butylamine and dodecylamine
selectively give the imines resulting from regioselective anti-
Markovnikov couplings (Scheme 2). This surprising change of
regioselectivity by changing the nature of the substituent of the
amine has been also observed by Beller using Cp2Ti(η2-Me3-
SiC2SiMe3)13f and Doye using Ind2TiMe2.15k However, it should
be noted that in our case the regioselectivity is 100%. Like the
enamine-imine mixtures shown in Scheme 1, the imines
resulting from aliphatic amines were transformed in quantitative
yield into the corresponding secondary amines, by treatment
with NaCNBH3/p-TsOH in tetrahydrofuran at room temperature.
Also in contrast to the reactions with anilines, for the reactions
shown in Scheme 2, the 2-diphenylphosphinoethyl substituent
does not appear to exercise a significant influence on the activity
of the half-sandwich precursor. Both compounds 2 and 6 are
much more efficient for the reactions with tert-butylamine than
for those with dodecylamine. Thus, while with the first of them
(entries 9, 10, 13, and 14) the quantitative transformation of the
alkynes into the corresponding imines occurs within short times
(0.25-0.5 h), with the latter (entries 11, 12, 15, and 16) con-
versions lower than 50% are achieved in all the cases after 24 h.
Cyclohexylamine also reacts with 1-octyne (entries 17 and 18)
and cyclohexylacetylene (entries 19 and 20) to give selectively
imines. However, in this case, although the formation of the
anti-Markovnikov products is favored, the regioselectivity of
the addition is much lower than in the previous cases, and
mixtures of the Markovnikov and anti-Markovnikov products
are formed, which were also transformed into the corresponding
secondary amines by reduction with NaCNBH3/p-TsOH (Scheme
3). For these reactions, the 2-diphenylphosphinoethyl susbtituent
does not exercise a significant influence either on the activity
of the precursor or on the regioselectivity of the hydroamination.
3. Hydroamination of Aromatic Alkynes. The trimethyl
complex 2 is also an efficient catalyst precursor for the addition
of one of the N-H bonds of 2,6-dimethylaniline, 2,6-diiso-
propylaniline, tert-butylamine, cyclohexylamine, and dodecyl-
amine to the carbon-carbon triple bond of alkynes such as
phenylacetylene and 1-phenylpropyne (Table 2). In all the cases,
the reactions lead to enamine-imine mixtures resulting from
the regioselective anti-Markovnikov couplings. The mixtures
were transformed in quantitative yield into the corresponding
secondary amines, by reduction with molecular hydrogen in the
presence of PtO2 (Scheme 4).
It should be noted that, unlike 1-octyne and cyclohexylacetyl-
ene, the products resulting from phenylacetylene and 1-phenyl-
propyne are always anti-Markovnikov. In addition, it should
also be pointed out that the regioselectivity of the addition is
100% for all studied reactions. This is in contrast to that
observed by Doye and co-workers, using the bis(indenyl)
derivative Ind2TiMe2 as catalyst precursor. They have found
that the regioselectivity of the reactions is influenced by the
nature of the substituent of the aromatic alkyne and the bulkiness
of the primary amine.15k

Half-Sandwich Alkyl-Titanium(IV) Complexes
Organometallics, Vol. 25, No. 17, 2006 4083
Table 1. Hydroamination of Terminal Aliphatic Alkynesa
a Reaction conditions: alkyne (2.40 mmol), amine (2.64 mmol), n-octane (2.40 mmol), catalyst (0.12 mmol, 5 mol %), toluene (2.0 mL), 100 °C. b Determined
1
by GC. c Determined by H NMR spectroscopy at the end of the reaction.
In terms of efficiency, complex 2 is comparable with the
(2-methoxyethyl)cyclopentadienyl derivative CpOTiMe3, within
the half-sandwich titanium family, the most efficient of the pre-
viously reported catalyst precursors. For some reactions, it has
even been shown to be more efficient than Ind2TiMe2, which
has been regarded as a “general catalyst”.11

4084 Organometallics, Vol. 25, No. 17, 2006
Buil et al.
Scheme 4
It is generally assumed that under the catalytic conditions
the metallocene precursors afford the half-sandwich catalytically
active amido-imido species (R′NH)(η5-C5R5)Ti(dNR′), which
add the alkyne to give azametallacyclobutene intermediates by
reversible [2 + 2] cycloaddition between the C-C triple and
Ti-N double bonds. The protonation of the heterometallacycle
by action of the amine, followed by an R-elimination reaction
in the resulting intermediates, leads to the hydroamination
products.12a,d,13f,15d,h,i,k,l,20
We have recently reported the preparation, spectroscopic char-
acterization between 60 and -60 °C, and the X-ray structure of
the amido-imido complex {(2,6-iPr2C6H3)NH}CpNTi{dN(2,6-
iPr2C6H3)}, containing a coordinated pendant dimethylamino
group, which in solution remains coordinated. In contrast with
the assumed catalytic cycle, this compound is completely inac-
tive for the hydroamination reactions with 2,6-diisopropylaniline,
despite that the related trimethyl derivative CpNTiMe3 is an
efficient catalyst precursor and that its reaction with 2,6-
diisopropylaniline also affords the amido-imido complex. To
rationalize these results, we suggested that the alkyne plays a
main role in the generation process of the catalytically active
species in the reactions initiated by CpNTiMe3.10
Table 2. Hydroamination of Aromatic Alkynesa
According to the assumed mechanism, for the activation of
{(2,6-iPr2C6H3)NH}CpNTi{dN(2,6-iPr2C6H3)} the dissociation
of the pendant amino group is necessary, and since the affinity
of the 2-diphenylphosphino unit toward the titanium atom is
lower than that of the 2-dimethylamino group, we decided to
prepare {(2,6-iPr2C6H3)NH}CpPTi{dN(2,6-iPr2C6H3)} (7) and
investigate its role in the hydroamination reactions initiated by
the trimethyl CpPTiMe3 precursor, with the intention of finding
some explanation to our results, from the point of view of the
assumed mechanism. The presence of a phosphine group in the
system certainly should facilitate the study.
The addition of 2.0 equiv of 2,6-diisopropylaniline to an NMR
tube containing a toluene-d8 solution of 2 gives rise to the
quantitative formation of 7, acoording to eq 2.
a Reaction conditions: alkyne (2.40 mmol), amine (2.64 mmol), n-octane
(2.40 mmol), CpPTiMe3 (0.12 mmol, 5 mol %), toluene (2.0 mL), 100 °C.
b Determined by GC. c Determined by 1H NMR spectroscopy at the end of
the reaction.
The results shown in Table 2 indicate that the yield of the
reactions is influenced mainly by the nature of the amine. Within
the reactions with aromatic amines, it is observed that the
quantitative transformation of the alkynes occurs with 2,6-
dimethylaniline faster than with 2,6-diisopropylaniline; that is,
for aromatic amines, the bulkiness of their substituents hinders
the reaction. In the opposite direction, the bulkier aliphatic
amines give rise to higher conversions. Thus, for both alkynes,
the conversions decrease in the sequence tert-butylamine >
cyclohexylamine > dodecylamine.
4. Comments about the Role of the Pendant Substituent
during the Catalysis. The first clear fact from our previous
results and those reported here is that the X group has a marked
influence on the efficiency of the CpXTiMe3 (X ) CH2CH2-
NMe2, H, CH2CH2OMe, CH2CH2PPh2) catalyst precursors for
the hydroamination reactions of terminal alkynes. The efficiency
increases as the affinity of the donor group of the cyclopenta-
dienyl pendant substituent toward the titanium atom decreases,
i.e., in the sequence NMe2 < OMe ≈ PPh2. Thus, while complex
CpNTiMe3 is less efficient than 6, CpOTiMe3 and 2 are more
efficient than 6.
In agreement with the presence of an amido ligand in 7, its
1H NMR spectrum contains a NH resonance at 9.34 ppm. The
isopropyl substituents of the aromatic rings of the amido and
imido ligands display multiplets at 4.14 and 3.71 ppm and four
doublets (JH-H ) 6.9 Hz) between 1.20 and 1.09 ppm for the
eight diasterotopic methyl group. This spectrum, as well as the
13C{1H} and 31P{1H} NMR spectra, which are temperature
invariant between 60 and -60 °C, reveals that the pendant
phosphine group of the (2-diphenylphosphinoethyl)cyclo-
pentadienyl ligand does not dissociate in solution, in agreement
with that observed for the related (2-dimethylaminoethyl)-
cyclopentadienyl derivative {(2,6-iPr2C6H3)NH}CpNTi{dN(2,6-
iPr2C6H3)}. Thus, due to the chirality of the titanium atom, the
1H NMR spectrum also shows an ABCD spin system for the
methylene resonances. It appears between 2.60 and 2.44 ppm,
whereas the resonances corresponding to the cyclopentadienyl
protons, which also display an ABCD spin system, are observed
between 6.39 and 5.42 ppm. In the 13C{1H} NMR spectrum,
the most noticeable fact is that the values of the P-Cipso coupling

Half-Sandwich Alkyl-Titanium(IV) Complexes
Organometallics, Vol. 25, No. 17, 2006 4085
Scheme 5
constants, 28 (δ, 131.2) and 30 (δ, 131.1) Hz, exceed those of
the P-Cortho coupling constants, 13 (δ, 133.6 and 133.5) Hz, in
the phosphino-phenyl resonances, while for compounds pos-
sessing a noncoordinated Ph2PCH2CH2 moiety an inverse
relationship is observed.8a,b The coordinated character of the
phosphine substituent of the cyclopentadienyl ligand is also
strongly supported by the chemical shift of the singlet observed
in the 31P{1H} NMR spectrum, 21.9 ppm. Moreover, it is not
very sensitive to the temperature (Figure 1).
The behavior of 7 is in total agreement with that of the related
amino derivative {(2,6-iPr2C6H3)NH}CpNTi{dN(2,6-iPr2C6H3)}.
Complex 7 does not react with 2,6-diisopropylaniline or
1-octyne. Furthermore, it is completely inactive for the hydro-
amination reactions with 2,6-diisopropylaniline. Again, the facts
indicate that amido-imido species of the type (RNH)CpXTi-
(dNR) do not play any active role in the intermolecular hydro-
amination of alkynes initiated by CpXTiMe3 (X ) CH2CH2-
NMe2, CH2CH2OMe, CH2CH2PPh2) precursors.
To corroborate the reasoning, we carried out in a NMR tube
the hydroamination of 1-octyne with 2,6-diisopropylaniline using
2 as a catalyst precursor. As expected, the 31P{1H} NMR
spectrum of the mixture shows two singlets in a 1:2 molar ratio.
That of intensity 1 appears at 22.1 ppm, the chemical shift found
for 7, while the other one, of intensity 2, is observed at -16.4
ppm, a chemical shift typical for a free 2-diphenylphosphino-
ethyl pendant substituent (see Figure 1).
In addition to a [2 + 2] cycloaddition between the C-C triple
bond of the alkyne and the Ti-N double bond of an imido
intermediate,21 two approaches can be used to effect the
hydroamination: (i) insertion of the C-C triple bond of the
alkyne into Ti-H or Ti-NHR bonds,12a,d,20,22 and (ii) nucleo-
philic attack of the amine to a coordinate η2-alkyne.12a,d,20 The
insertion of a coordinated alkyne into a Ti-H or Ti-NHR bond
should produce the diminution of the coordination number
around the titanium atom in one unit, which should favor the
coordination of the pendant donor group, resulting in the
deactivation of the system. So, the nucleophilic addition of the
amine to a coordinate η2-alkyne seems to be the most reasonable
proposal.
Scheme 5 shows a catalytic cycle for the intermolecular
hydroamination of alkynes, which is consistent with our experi-
mental observations and takes into account the previous consid-
erations. The nucleophilic attack of the amine to a coordinated
η2-alkyne of a half-sandwich six-coordinate species containing
a free pendant donor substituent at the cyclopentadienyl ring
and both substrates, the amine as amido and the alkyne forming
a metallacyclopropene, should lead to azonium-metallacyclo-
propene intermediates. The 1,3-hydrogen shift from the nitrogen
The systematic study of the CpXTiLn systems in the solid
state and in solution proves that the stability of the bond between
the titanium atom and the pendant donor group is higher for
six-coordinate derivatives than for seven-coordinate compounds.
So, since the pendant group seems to be dissociated during the
hydroamination reactions, it appears reasonable to think that
the catalytically active species are six-coordinate complexes
containing a free pendant donor group. Thus, one should expect
that under the catalytic conditions the inactive six-coordinate
amido-imido species (RNH)CpXTi(dNR), with the X group
coordinated to the metal center, coexist with active six-
coordinate intermediates containing a dissociated pendant donor
group. The concentration of the latter should increase as the
affinity of the pendant donor group toward the titanium atom
decreases, in agreement with the increase of the efficiency of
the precursor as the affinity of its pendant donor group decreases.
(20) Walsh, P. J.; Baranger, A. M.; Bergman, R. G. J. Am. Chem. Soc.
1992, 114, 1708.
(21) Straub, T.; Haskel, A.; Neyroud, T. G.; Kapon, M.; Botoshansky,
M.; Eisen, M. S. Organometallics 2001, 20, 5017.

4086 Organometallics, Vol. 25, No. 17, 2006
Buil et al.
atom to the C(sp2) of the metallacycle, promoted by free amine,
should afford coordinated enamines. In this context, it should
be mentioned that the addition of electrophiles to the CR carbon
atom of early transition metal alkylidene complexes is a well-
known process.23 The enamine could be replaced by an alkyne
molecule to regenerate the active species.
compounds are reached. The comparison of the thermodynamic
parameters of these equilibria with those of the systems CpN-
TiMexCl3-x and CpOTiMexCl3-x (CpN ) C5H4CH2CH2NMe2,
CpO ) C5H4CH2CH2OMe, x ) 1-3) reveals that the affinity
of the donor group of the cyclopentadienyl substituent toward
the titanium atom decreases in the sequence NMe2 > OMe g
PPh2. In contrast to these alkyl compounds, the pendant donor
group of the amido-imido complex {(2,6-iPr2C6H3)NH}CpP-
Ti{dN(2,6-iPr2C6H3)}, which is formed by reaction of CpP-
TiMe3 with 2,6-diisopropylaniline, remains coordinated in
solution between 60 and -60 °C.
The trimethyl derivative CpPTiMe3 is an efficient catalyst
precursor for the regioselective hydroamination of aliphatic (1-
octyne and cyclohexylacetylene) and aromatic (phenylacetylene
and 1-phenylpropyne) alkynes with aromatic (2,6-dimethylani-
line and 2,6-diisopropylaniline) and aliphatic (tert-butylamine,
dodecylamine, and cyclohexylamine) amines. The Markovnikov
or anti-Markovnikov nature of the obtained products depends
on the aliphatic or aromatic character of both the alkyne and
the amine. Markovnikov products with regioselectivities of
100% are formed from the reactions between aliphatic alkynes
and aromatic amines, while anti-Markovnikov derivatives with
regioselectivities of 100% are obtained from the reactions of
aromatic alkynes with all the studied amines and from the
reactions of the aliphatic alkynes with tert-butylamine and
dodecylamine. The reaction of 1-octyne and cyclohexylacetylene
with cyclohexylamine gives mixtures of both types of products.
The comparison of these results with those previously
reported for CpNTiMe3 and CpOTiMe3 shows that the efficiency
of this type of precursors increases as the affinity of the donor
pendant group of the cyclopentadienyl ligand toward the
titanium atom decreases, i.e., in the sequence NMe2 < OMe ≈
PPh2. Since the imido-amido complexes {(2,6-iPr2C6H3)NH}CpX-
Ti{dN(2,6-iPr2C6H3)} (CpX ) CpN, CpP) are completely inac-
tive for the hydroamination reactions with 2,6-diisopropylaniline,
this sequence suggests that during the catalysis the pendant
donor group is not coordinated to the titanium atom.
In conclusion, complex CpPTiMe3 is an efficient catalyst
precursor for the hydroamination of aliphatic and aromatic
alkynes with aromatic and aliphatic amines. Markovnikov or
anti-Markovnikov products are obtained regioselectively de-
pending upon the nature of the substituents of the alkynes and
amines. According to the results of the systematic study of the
behavior of the pendant substituent of the cyclopentadienyl
ligand of complexes CpXTiLn (X ) CH2CH2NMe2, CH2CH2-
OMe, CH2CH2PPh2), the PPh2 group is not coordinated to the
titanium atom during the catalysis.
Metallacyclopropene complexes with a metal-carbon double
bond, as those shown in Scheme 5, are considered important
intermediates in several catalytic reactions including alkyne
oligomerization,24 alkyne cyclization,25 and hydrodesulfuriza-
tion.26 They have been isolated mainly with early transition
metals27 and a few with 8 group elements.28 With some excep-
tion, their formation generally involves the external nucleo-
philic attack on coordinated alkyne ligands.29 Theoretical calcu-
lations show that their structure is stabilized by the presence of
an aromatic substituent at the C(sp2) atom. The stabilization
already operative for alkyl substitution through hyperconjugation
of the alkyl group is magnified for a phenyl group, where con-
jugation with a true π-system is possible.28b The participation
of this type of intermediates in the intermolecular hydroami-
nation of C-C triple bonds is certainly consistent with the fact
that aromatic alkynes always selectively give anti-Markovnikov
products.
Concluding Remarks
This study shows the preparation and spectroscopic charac-
terization of the first half-sandwich alkyl-titanium complexes
stabilized by a cyclopentadienyl ligand bearing a phosphine
pendant group, as well as the catalytic properties of the CpPTi
(CpP ) C5H4CH2CH2PPh2) moiety in the hydroamination of
aliphatic and aromatic alkynes with aromatic and aliphatic
amines.
The previously reported complex CpPTiCl3 reacts with 1.0,
2.0, and 3.0 equiv of MeMgCl to afford the mono-, di-, and
trimethyl derivatives CpPTiMeCl2, CpPTiMe2Cl, and CpPTiMe3,
respectively. In solution, the pendant P-donor substituent of the
cyclopentadienyl ligand is involved in a coordination-dissocia-
tion process, and equilibria between six- and seven-coordinate
(22) (a) Li, Y.; Marks, T. J. J. Am. Chem. Soc. 1998, 120, 1757. (b)
Ryu, J.-S.; Li, G. Y.; Marks, T. J. J. Am. Chem. Soc. 2003, 125, 12584. (c)
Hong, S.; Marks, T. J. Acc. Chem. Res. 2004, 37, 673.
(23) (a) Schrock, R. R. J. Chem. Soc., Dalton Trans. 2001, 2541. (b)
Schrock, R. R. Chem. ReV. 2002, 102, 145.
(24) Carlton, L.; Davidson, J. L.; Ewing, P.; Manojlovic´-Muir, L.; Muir,
K. W. J. Chem. Soc., Chem. Commun. 1985, 1474.
(25) Davidson, J. L.; Vasapollo, G.; Manojlovic´-Muir, L.; Muir, K. W.
J. Chem. Soc., Chem. Commun. 1982, 1025.
(26) Spera, M. L.; Harman, W. D. J. Am. Chem. Soc. 1997, 119, 8843.
(27) See for example: (a) Carfagna, C.; Deeth, R. J.; Green, M.; Mahon,
M. F.; McInnes, J. M.; Pellegrini, S.; Woolhouse, C. B. J. Chem. Soc.,
Dalton Trans. 1995, 3975. (b) Kiplinger, J. L.; King, M. A.; Fechtenko¨tter,
A.; Arif, A. M.; Richmond, T. G. Organometallics 1996, 15, 5292. (c)
Kiplinger, J. L.; Richmond, T. G.; Arif, A. M.; Du¨cker-Benfer, C.; van
Eldik, R. Organometallics 1996, 15, 1545. (d) Kiplinger, J. L.; Richmond,
T. G. Polyhedron 1997, 16, 409. (e) Casey, C. P.; Brady, J. T. Organo-
metallics 1998, 17, 4620. (f) Casey, C. P.; Brady, J. T.; Boller, T. M.;
Weinhold, F.; Hayashi, R. K. J. Am. Chem. Soc. 1998, 120, 12500. (g)
Legzdins, P.; Lumb, S. A.; Rettig, S. J. Organometallics 1999, 18, 3128.
(h) Debad, J. D.; Legzdins, P.; Lumb, S. A.; Rettig, S. J.; Batchelor, R. J.;
Einstein, F. W. B. Organometallics 1999, 18, 3414. (i) Frohnapfel, D. S.;
Enriquez, A. E.; Templeton, J. L. Organometallics 2000, 19, 221. (j)
Guillemot, G.; Solari, E.; Scopelliti, R.; Floriani, C. Organometallics 2001,
20, 2446.
(28) (a) Chen, H.; Harman, W. D. J. Am. Chem. Soc. 1996, 118, 5672.
(b) Buil, M. L.; Eisenstein, O.; Esteruelas, M. A.; Garc´ıa-Yebra, C.;
Gutie´rrez-Puebla, E.; Oliva´n, M.; On˜ate, E.; Ruiz, N.; Tajada, M. A.
Organometallics 1999, 18, 4949. (c) Buil, M. L.; Esteruelas, M. A.; Garc´ıa-
Yebra, C.; Gutie´rrez-Puebla, E.; Oliva´n, M. Organometallics 2000, 19, 2184.
(d) Barrio, P.; Esteruelas, M. A.; On˜ate, E. Organometallics 2003, 22, 2472.
(29) Templeton, J. L. AdV. Organomet. Chem. 1989, 29, 1.
Experimental Section
General Methods and Instrumentation. All reactions were
carried out under argon with rigorous exclusion of air using
Schlenk-line or drybox techniques. Solvents were dried by the usual
procedures and distilled under argon prior to use. The starting
material CpPTiCl3 (1) was prepared by the published method.5
Alkynes were distilled and amines were distilled from CaH2 and
stored in the drybox. All other reagents were purchased from
commercial sources and were used without further purification. The
course of the catalytic reactions was followed using a Hewlett-
Packard 5890 series gas chromatograph with a flame ionization
detector, using a 100% cross-linked methyl silicone gum column
(30 m × 0.25 mm, with 0.25 µm film thickness) and n-octane as
the internal standard. The oven conditions used are as follows:
35 °C (hold 6 min) to 280 °C at 25 °C/min (hold 5 min). The
reaction products were identified by GC-MS and by H and 13C-
1

Half-Sandwich Alkyl-Titanium(IV) Complexes
Organometallics, Vol. 25, No. 17, 2006 4087
{1H} NMR spectroscopies. GC-MS experiments were run on an
Agilent 5973 mass selective detector interfaced to an Agilent 6890
series gas chromatograph system. Samples were injected into a 30 m
× 250 µm HP-5MS 5% phenyl methyl siloxane column with a
film thickness of 0.25 µm (Agilent). The GC oven temperature was
programmed as follows: 35 °C for 6 min to 280 °C at 25 °C/min
for 5 min. The carrier gas was helium at a flow of 1 mL/min.
1H, 31P{1H}, and 13C{1H} NMR spectra were recorded on either
a Varian UNITY 300, a Varian Gemini 2000, a Bruker AXR 300,
or a Bruker Avance 300 MHz instrument. Chemical shifts (ex-
pressed in parts per million) are referenced to residual solvent peaks
(1H, 13C{1H}) or external H3PO4 (31P{1H}). Coupling constants, J,
are given in hertz. C and H analyses were carried out in a Perkin-
Elmer 2400 CHNS/O analyzer.
Preparation of CpPTiMe3 (2). To a dark red suspension of 1
(610 mg, 1.41 mmol) in 20 mL of diethyl ether at -40 °C was
added dropwise 3.0 equiv of MeMgCl (1.40 mL, 4.24 mmol, 3 M
in tetrahydrofuran). After addition, the mixture was warmed slowly
to 20 °C and stirred for 4 h. The volatiles were removed under
reduced pressure, and the residue was extracted with pentane (3 ×
50 mL). The solvent was removed from the resultant orange solution
under vacuum, affording an orange oil. Yield: 252 mg (48%). Anal.
Calcd for C22H27PTi: C, 71.36; H, 7.36. Found: C, 71.85; H, 7.56.
1H NMR (300 MHz, C7D8, 293 K): δ 7.39-6.98 (m, 10H, Ph),
5.81, 5.72 (both m, each 2H, C5H4), 2.46-2.38 (m, 2H, CH2), 2.21-
2.15 (m, 2H, CH2), 1.11 (s, 9H, TiMe3). 31P{1H} NMR (121.42
MHz, C7D8, 293 K): -15.4 (br s). 31P{1H} NMR (121.42 MHz,
C7D8, 183 K): 9.2 (br s).13C{1H} NMR (75.42 MHz, C7D8, 253
2.90 (s, 6H, CH2Ph), 2.11-1.99 (m, 4H, CH2CH2). 31P{1H} NMR
(121.42 MHz, C7D8, 293 K): -15.8 (br s). 31P{1H} NMR (121.42
MHz, C7D8, 183 K): -17.2 (br s). 13C{1H} NMR (75.42 MHz,
3
C7D8, 293 K, plus APT): δ 148.6 (Cipso Ph), 139.1 (d, JCP ) 14,
1
2
Cipso C5H4), 136.4 (d, JCP ) 15, Cipso Ph), 133.2 (d, JCP ) 19,
o-Ph), 129.5 (p-Ph), 128.5 (Ph), 128.7 (d, 3JCP ) 7, m-Ph), 126.7,
122.9 (Ph), 117.9, 116.1 (C5H4), 92.3 (CH2Ph), 29.9 (d, 1JCP ) 15,
2
CH2P), 26.5 (d, JCP ) 17, C5H4CH2).
Preparation of {(2,6-iPr2C6H3)NH}CpPTi{dN(2,6-iPr2C6H3)}
(7). An orange solution of 2 (200 mg, 0.54 mmol) in 10 mL of
toluene was treated with 2.0 equiv of 2,6-diisopropylaniline (210
µL, 1.08 mmol) at 0 °C. Immediately gas evolution was observed.
The mixture was heated to 100 °C and stirred for 4 h. Then the
solvent was removed under vacuum and the product was washed
with pentane (4 × 3 mL) and dried in vacuo. The product was
obtained as a red oil. In our hands it was not possible to completely
remove free 2,6-diisopropylaniline, and attempts to obtain satisfac-
tory combustion analysis were unsuccessful. Yield: 274 mg (75%).
1H NMR (300 MHz, C7D8, 293 K): δ 9.34 (s, 1H, NH), 7.74-
7.39 (m, 10H, Ph), 7.14-6.80 (m, 6H, C6H3), 6.39, 6.06, 5.91, 5.42
(all m, each 1H, C5H4), 4.14, 3.71 (both m, each 2H, CH(CH3)2),
2.60-2.44 (m, 4H, CH2CH2), 1.20, 1.19, 1.12, 1.09 (all d, 3JHH
)
6.9, each 6H, CH(CH3)2). 31P{1H} NMR (121.42 MHz, C7D8, 293
K): 21.9 (s). 31P{1H} NMR (121.42 MHz, C7D8, 213 K): 24.1
(s). 13C{1H} NMR (75.42 MHz, C6D6, 293 K, plus APT and
HETCOR): δ 156.3 (d, 3JCP ) 1, Cipso N), 153.7 (Cipso N), 143.1,
2
3
143.0 (o-C6H3), 133.6 (d, JCP ) 13, o-Ph), 133.6 (d, JCP ) 7,
2
2
Cipso C5H4), 133.5 (d, JCP ) 13, o-Ph), 133.3, 133.0 (both d, JCP
) 2, p-Ph), 131.2 (d, JCP ) 28, Cipso Ph), 131.1 (d, JCP ) 30,
1
1
3
2
K): δ 137.8 (d, JCP ) 9, Cipso C5H4), 133.1 (d, JCP ) 18, o-Ph),
3
3
Cipso Ph), 130.7 (d, JCP ) 15, m-Ph), 130.6 (d, JCP ) 15, m-Ph),
122.3, 122.0, 120.6 (C6H3), 114.3, 107.6, 106.6, 105.4 (C5H4), 36.3
(d, 1JCP ) 23, CH2P), 28.7, 27.9 (CH(CH3)2), 24.7, 24.2, 24.1 (CH-
(CH3)2), 24.1 (C5H4CH2), 23.9 (CH(CH3)2).
1
3
132.5 (d, JCP ) 14, Cipso Ph), 128.8 (d, JCP ) 7, m-Ph), 128.7
1
(p-Ph), 113.4, 112.0 (C5H4), 62.0 (TiMe3), 30.0 (d, JCP ) 10,
2
CH2P), 26.6 (d, JCP ) 20, C5H4CH2).
Preparation of CpPTiMe2Cl (3). The same procedure described
for 2 was followed, except that 1 (566 mg, 1.31 mmol) and 2.0
equiv of MeMgCl (0.87 mL, 2.62 mmol, 3 M in tetrahydrofuran)
were used. The product was obtained as a red oil. Yield: 226 mg
(44%). Anal. Calcd for C21H24ClPTi: C, 64.53; H, 6.20. Found:
Reaction of CpPTiMe3 (2) with 1-Octyne and 2,6-Diisopropyl-
aniline. In an NMR tube, complex CpPTiMe3 (2) (15 mg, 0.04
mmol) was dissolved in C7D8. 1-Octyne (113 µL, 0.74 mmol) and
2,6-diisopropylaniline (157 µL, 0.81 mmol) were added. The
1
mixture was warmed at 100 °C. The tube was checked by H and
1
C, 65.11; H, 5.65. H NMR (300 MHz, C7D8, 293 K): δ 7.39-
31P{1H} NMR spectroscopy. After 30 min, the 1H NMR spectrum
showed the formation of enamine CH3(CH2)5C(dCH2)NH-2,6-iPr2-
C6H3, and the 31P{1H} NMR spectrum showed two singlets at 22.1
and -16.4 ppm in a 1:2 molar ratio.
6.97 (m, 10H, Ph), 5.95, 5.78 (both m, each 2H, C5H4), 2.48-2.30
(m, 4H, CH2CH2), 1.25 (s, 6H, TiMe2). 31P{1H} NMR (121.42
MHz, C7D8, 293 K): -15.6 (br s). 31P{1H} NMR (121.42 MHz,
C7D8, 183 K): 12.3 (br s). 13C{1H} NMR (75.42 MHz, C7D8, 253
Determination of Constants and Thermodynamic Parameters
for the Equilibriums Shown in Figure 1. Variable-temperature
31P{1H} NMR spectra of 2 (-90 to 20 °C), 3 (-90 to 20 °C), and
4 (-90 to 20 °C) were recorded in toluene-d8. Equilibrium con-
stants, K, were derived from the temperature-dependent δ(31P{1H})
using eq 1. Thermodynamic parameters were calculated from the
equilibrium constants according to eq 3.
K, plus APT): δ 135.9 (d, 3JCP ) 8, Cipso C5H4), 134.9 (d, 1JCP
)
2
9, Cipso Ph), 133.3 (d, JCP ) 13, o-Ph), 129.6 (p-Ph), 128.8 (d,
3JCP ) 6, m-Ph), 116.3, 114.3 (C5H4), 68.5 (TiMe2), 30.0 (br, CH2P),
2
24.9 (d, JCP ) 20, C5H4CH2).
Preparation of CpPTiMeCl2 (4). The same procedure described
for 2 was followed, except that 1 (526 mg, 1.22 mmol) and 1.0
equiv of MeMgCl (0.40 mL, 1.22 mmol, 3 M in tetrahydrofuran)
were used. The product was obtained as an orange solid. Yield:
155 mg (31%). Anal. Calcd for C20H21Cl2PTi: C, 58.40; H, 5.16.
∆S° ∆H°
ln K )
-
(3)
R
RT
1
Found: C, 58.79; H, 5.07. H NMR (300 MHz, C7D8, 293 K): δ
7.45-6.97 (m, 10H, Ph), 6.06, 5.85 (both m, each 2H, C5H4), 2.50-
2.35 (m, 4H, CH2CH2), 1.68 (s, 3H, TiMe). 31P{1H} NMR (121.42
MHz, C7D8, 293 K): -14.5 (br s). 31P{1H} NMR (121.42 MHz,
C7D8, 183 K): 28.3 (br s). 13C{1H} NMR (75.42 MHz, C7D8, 253
Reasonable values for δmin and δmax were obtained by computer-
assisted iteration: δmin and δmax were optimized in such a way that
plotting of ln K versus 1/T gives the straightest line possible.
General Procedure for Hydroamination. A Schlenk tube
equipped with a Teflon stopcock and a magnetic stirring bar was
charged with the alkyne (2.40 mmol), the amine (2.64 mmol),
complex 2 or complex 6 (0.12 mmol, 5.0% mol), toluene (2 mL),
and n-octane (2.40 mmol). The Schlenk was removed from the
glovebox and heated at 100 °C. The reaction was monitored by
periodic GC analysis of samples removed with a syringe. Either
on completion of the reaction or after 24 h, the volatiles were
removed under reduced pressure and the residue was analyzed by
1H and 13C{1H} NMR spectroscopy and by GC-MS.
K, plus APT): δ 138.2 (d, 3JCP ) 8, Cipso C5H4), 134.9 (d, 1JCP
)
2
9, Cipso Ph), 133.9 (d, JCP ) 12, o-Ph), 129.7 (p-Ph), 128.8 (br,
m-Ph), 119.2, 118.1 (C5H4), 78.5 (TiMe), 31.2 (br, CH2P), 26.6 (d,
2JCP ) 20, C5H4CH2).
Preparation of CpPTi(CH2Ph)3 (5). The same procedure
described for 2 was followed, except that 1 (616 mg, 1.43 mmol)
and 3.0 equiv of PhCH2MgCl (2.1 mL, 4.28 mmol, 2 M in
tetrahydrofuran) were used. The product was obtained as a red oil.
Yield: 526 mg (62%). Anal. Calcd for C40H39PTi: C, 80.24; H,
1
6.58. Found: C, 79.70; H, 7.15. H NMR (300 MHz, C7D8, 293
General Procedure for Hydrogenation. Enamines and imines
resulting from hydroamination of aromatic alkynes were hydroge-
K): δ 7.32-6.70 (m, 25H, Ph), 5.54, 5.48 (both m, each 2H, C5H4),

4088 Organometallics, Vol. 25, No. 17, 2006
Buil et al.
nated as described elsewhere.10,11 Enamines and imines resulting
from hydroamination of aliphatic alkynes were hydrogenated as
follows: The crude hydroamination product was dissolved in THF
(2.0 mL). NaCNBH3 (302 mg, 4.8 mmol) and p-toluenesulfonic
acid monohydrate (46 mg, 0.24 mmol) were added, and the mixture
was stirred at room temperature. After 4 h, diethyl ether (4.0 mL)
and 2 N HCl (4.0 mL) were added. The mixture was stirred for 1 h
at room temperature. The organic layer was separated, and saturated
NaHCO3 solution was added to the water layer until pH ) 7 was
reached. The water layer was extracted with diethyl ether (2 × 4
mL). The combined organic layers were dried with MgSO4, and
filtration, concentration, and purification by flash chromatography
on silica gel afforded the amines, whose purity was checked by 1H
and 13C{1H} NMR spectroscopy and by GC-MS.
(CH2), 24.0 (CH(CH3)2), 22.8 (CH2), 16.2 (CHCH3), 14.2 (CH3-
CH2). MS: m/z 289 (M+), 204 (M+ - (CH3(CH2)5)).
Hydroamination of 1-Octyne with tert-Butylamine. CH3-
(CH2)5CH2CHdNtBu: 1H NMR (300 MHz, C6D6, 293 K): δ 7.46
(t, J ) 4.5, 1H, CH), 2.20-2.14 (m, 2H, CH2CH), 1.47-1.17 (m,
10H, (CH2)5CH2), 1.15 (s, 9H, C(CH3)3), 0.86 (t, J ) 5.4, 3H, CH3).
13C{1H} NMR (75.42 MHz, C6D6, 293 K, plus APT): δ 157.1
(CH), 56.3 (C(CH3)3), 36.4, 31.9 (CH2), 29.7 (C(CH3)3), 29.4, 29.3,
26.1, 22.8 (CH2), 14.0 (CH3). MS: m/z 183 (M+), 168 (M+ - CH3).
CH3(CH2)6CH2NHtBu: 1H NMR (300 MHz, C6D6, 293 K): δ
9.01 (br s, 1H, NH), 2.62, 1.98 (both m, each 2H, CH2), 1.49-
1.20 (m, 10H, CH2), 1.29 (s, 9H, C(CH3)3), 0.95 (t, J ) 6.3, 3H,
CH3). 13C{1H} NMR (75.42 MHz, C6D6, 293 K, plus APT, COSY,
and HETCOR): δ 56.8 (C(CH3)3), 41.9, 32.0, 29.5, 29.4, 27.2, 26.7
(CH2), 25.5 (C(CH3)3), 22.9 (CH2), 14.2 (CH3). MS: m/z 185 (M+),
170 (M+ - CH3).
Hydroamination of 1-Octyne with Dodecylamine. CH3-
(CH2)5CH2CHdNCH2(CH2)10CH3: 1H NMR (300 MHz, C6D6,
293 K): δ 7.47 (t, J ) 4.5, 1H, CHd), 3.36 (t, J ) 5.1, 2H, CH2),
2.18-2.10 (m, 2H, CH2CH), 1.90-1.40 (m, 10H, CH2), 1.27-
1.21 (m, 20H, CH2), 0.91-0.84 (m, 6H, CH3). 13C{1H} NMR (75.42
MHz, C6D6, 293 K, plus APT and HETCOR): δ 163.1 (CHd),
61.8, 35.8, 32.2, 32.0, 31.3, 29.9, 29.8, 29.4, 27.6, 26.1, 22.9 (CH2),
14.1, 14.0 (CH3). MS: m/z 295 (M+), 210 (M+ - CH3(CH2)5).
CH3(CH2)6CH2NHCH2(CH2)10CH3: 1H NMR (300 MHz, C6D6,
293 K): δ 2.75-2.55 (m, 4H, CH2), 1.85-1.50 (m, 10H, CH2),
1.40-1.20 (m, 22H, CH2), 0.93-0.90 (m, 6H, CH3). 13C{1H} NMR
(75.42 MHz, C6D6, 293 K, plus APT and HETCOR): δ 53.4, 48.1,
32.4, 32.1, 30.3-29.4, 28.7, 27.0, 26.5, 26.2, 25.9 (CH2), 14.1, 14.0
(CH3). MS: m/z 297 (M+), 212 (M+ - CH3(CH2)5).
Hydroamination of 1-Octyne with Cyclohexylamine. CH3-
(CH2)5CH2CHdNCy: 1H NMR (300 MHz, C6D6, 293 K): δ 7.45
(t, J ) 4.5, 1H, CHd), 2.89-2.80 (m, 1H, CH Cy), 2.14-2.07
(m, 2H, CH2CH), 1.74-1.09 (m, 20H, CH2), 0.84 (t, J ) 7.0, 3H,
CH3). 13C{1H} NMR (75.42 MHz, C6D6, 293 K, plus APT and
HETCOR): δ 160.9 (CHd), 69.9 (CH Cy), 35.9, 34.8, 31.9, 29.3,
26.1, 25.9, 24.8, 22.8 (CH2), 14.1 (CH3). CH3(CH2)5C(CH3)d
NCy: 1H NMR (300 MHz, C6D6, 293 K): δ 3.27-3.18 (m, 1H,
CH Cy), 1.74-1.09 (m, 20H, CH2), 1.47 (s, 3H, CH3), 0.84 (t, J )
7.0, 3H, CH3CH2). 13C{1H} NMR (75.42 MHz, C6D6, 293 K, plus
APT and HETCOR): δ 164.2 (Cd), 59.0 (CH Cy), 42.4, 34.0,
32.1, 29.5, 26.4, 26.3, 24.9, 22.9 (CH2), 16.1 (CH3), 14.1 (CH3-
CH2). MS: m/z 209 (M+), 166 (M+-(CH3(CH2)2)). CH3(CH2)6-
CH2NHCy: 1H NMR (300 MHz, C6D6, 293 K): δ 2.56 (t, J )
6.3, 2H, CH2N), 2.39-2.31 (m, 1H, CH Cy), 1.80-1.05 (m, 22H,
CH2), 0.87 (t, J ) 7.2, 3H, CH3). 13C{1H} NMR (75.42 MHz, C6D6,
293 K, plus APT, COSY, and HETCOR): δ 56.9 (CH Cy), 47.2,
33.9, 32.1, 31.0, 29.8, 26.5, 25.6, 25.0, 22.9 (CH2), 14.1 (CH3).
CH3(CH2)5CH(CH3)NHCy: 1H NMR (300 MHz, C6D6, 293 K):
δ 2.74-2.68 (m, 1H, CH), 2.56-2.46 (m, 1H, CH Cy), 1.80-1.05
(m, 20H, CH2), 0.99 (d, J ) 6.0, 3H, CHCH3), 0.87 (t, J ) 7.2,
3H, CH3). 13C{1H} NMR (75.42 MHz, C6D6, 293 K, plus APT,
COSY, and HETCOR): δ 53.4 (CH Cy), 49.4 (CH), 34.9, 33.9,
32.0, 31.0, 29.6, 27.7, 25.6, 22.9 (CH2), 21.3 (CHCH3), 14.1 (CH3).
MS: m/z 211 (M+), 168 (M+ - (CH3(CH2)2)).
Hydroamination of Cyclohexylacetylene with 2,6-Dimethyl-
aniline. CyC(CH3)dN-2,6-Me2C6H3: 1H NMR (300 MHz, C6D6,
293 K): δ 7.18-7.02 (m, 3H, Ph), 2.10-2.03 (m, 1H, CH), 1.98
(s, 6H, CH3), 1.83-1.15 (m, 10H, CH2), 1.28 (s, 3H, CH3). 13C-
{1H} NMR (75.42 MHz, C6D6, 293 K, plus APT and HETCOR):
δ 173.6 (Cd), 149.8 (Cipso Ph), 128.5 (Ph), 125.4 (Cipso Ph), 122.5
(Ph), 48.6 (CH), 30.5, 26.3 (CH2), 17.8 (CH3), 17.3 (CCH3). MS:
m/z 229 (M+), 146 (M+ - Cy). CyCH(CH3)NH-2,6-Me2C6H3:
1H NMR (300 MHz, C6D6, 293 K): δ 7.04-6.90 (m, 3H, Ph),
3.03-2.90 (m, 1H, CH), 2.02 (s, 6H, CH3), 1.93-0.87 (m, 11H,
Cy), 1.00 (d, J ) 4.8, 3H, CHCH3). 13C{1H} NMR (75.42 MHz,
C6D6, 293 K, plus APT, COSY, and HETCOR): δ 132.8, 132.0
Characterization Data of New Compounds. Hydroamination
of 1-Octyne with 2,6-Dimethylaniline. CH3(CH2)5C(dCH2)NH-
2,6-Me2C6H3: 1H NMR (300 MHz, C6D6, 293 K): δ 7.18-7.02
(m, 3H, Ph), 4.03 (br s, 1H, NH), 3.74, 3.45 (both s, each 1H,
dCH2), 2.25 (s, 6H, CH3), 2.06-2.01, 1.81-1.76, 1.56-1.49 (all
m, 6H, CH2), 1.38-1.28 (m, 4H, CH2), 0.91 (t, J ) 7.2, 3H,
CH2CH3). 13C{1H} NMR (75.42 MHz, C6D6, 293 K, plus APT and
HETCOR): δ 148.0 (Cd), 143.3, 139.5 (Cipso Ph), 129.3, 128.5
(Ph), 80.5 (dCH2), 36.1, 34.4, 31.5, 29.3, 28.5 (CH2), 18.1 (CH3),
14.1 (CH3CH2). CH3(CH2)5C(CH3)dN-2,6-Me2C6H3: 1H NMR
(300 MHz, C6D6, 293 K): δ 7.04-6.89 (m, 3H, Ph), 2.21 (t, J )
7.3, 2H, CH2Cd), 2.00 (s, 6H, CH3), 1.68-1.63 (m, 2H, CH2),
1.37-1.24 (m, 6H, CH2), 1.28 (s, 3H, CH3), 0.91 (t, J ) 7.3, 3H,
CH2CH3). 13C{1H} NMR (75.42 MHz, C6D6, 293 K, plus APT and
HETCOR): δ 170.2 (Cd), 149.9 (Cipso Ph), 128.6 (Ph), 125.6 (Cipso
Ph), 122.6 (Ph), 40.6, 31.9, 29.3, 26.3, 22.8 (CH2), 19.3 (dCCH3),
17.9 (CH3), 14.1 (CH3CH2). MS: m/z 231 (M+), 146 (M+ - (CH3-
(CH2)5)). CH3(CH2)5CH(CH3)NH-2,6-Me2C6H3: 1H NMR (300
MHz, C6D6, 293 K): δ 6.85-6.66 (m, 3H, Ph), 3.04-2.97 (m,
1H, CH), 2.12 (s, 6H, CH3), 1.73-1.07 (m, 10H, CH2), 1.00 (d, J
) 6.6, 3H, CHCH3), 0.92 (t, J ) 7.2, 3H, CH2CH3). 13C{1H} NMR
(75.42 MHz, C6D6, 293 K, plus APT, COSY, and HETCOR): δ
132.3, 130.7 (Cipso Ph), 129.8, 128.9 (Ph), 61.3 (CH), 32.8, 31.6,
28.7, 25.6, 22.6 (CH2), 18.1 (CH3), 15.9 (CHCH3), 14.0 (CH3CH2).
MS: m/z 233 (M+), 148 (M+ - (CH3(CH2)5)).
Hydroamination of 1-Octyne with 2,6-Diisopropylaniline.
1
CH3(CH2)5C(dCH2)NH-2,6-iPr2C6H3: H NMR (300 MHz, C6D6,
293 K): δ 7.18-6.82 (m, 3H, Ph), 4.00 (br s, 1H, NH), 3.70, 3.42
(both s, each 1H, dCH2), 3.29 (sept, J ) 6.9, 2H, CH(CH3)2), 2.03
(t, J ) 7.6, 2H, CH2Cd), 1.45-1.38 (m, 2H, CH2), 1.24-1.07 (m,
6H, CH2), 1.14 (d, J ) 6.9, 12H, CH(CH3)2), 0.91-0.87 (m, 3H,
CH2CH3). 13C{1H} NMR (75.42 MHz, C6D6, 293 K, plus APT and
HETCOR): δ 150.4 (Cd), 147.1, 136.5 (Cipso Ph), 125.6, 123.8
(Ph), 81.0 (dCH2), 36.1, 32.0, 29.2, 28.3 (CH2), 28.2 (CH(CH3)2),
24.1 (CH(CH3)2), 22.9 (CH2), 14.1 (CH3). CH3(CH2)5C(CH3)d
N-2,6-iPr2C6H3: 1H NMR (300 MHz, C6D6, 293 K): δ 7.18-
7.02 (m, 3H, Ph), 2.89 (sept, J ) 6.9, 2H, CH(CH3)2), 2.25 (t, J )
7.5, 2H, CH2Cd), 1.75-1.63 (m, 2H, CH2), 1.40 (s, 3H, CH3),
1.35-1.23 (m, 6H, CH2), 1.20, 1.17 (both d, J ) 6.9, each 6H,
CH(CH3)2), 0.91-0.87 (m, 3H, CH2CH3). 13C{1H} NMR (75.42
MHz, C6D6, 293 K, plus APT and HETCOR): δ 170.2 (Cd), 137.8
136.2 (Cipso-Ph), 123.5, 123.3 (Ph), 40.7, 31.9, 29.3 (CH2), 28.2
(CH(CH3)2), 26.2 (CH2), 23.2 (CH(CH3)2), 22.9 (CH2), 22.8 (CH-
(CH3)2), 20.0 (CCH3), 14.0 (CH3CH2). MS: m/z 287 (M+), 202
(M+ - (CH3(CH2)5)). CH3(CH2)5CH(CH3)NH-2,6-iPr2C6H3: 1H
NMR (300 MHz, C6D6, 293 K): δ 7.11-6.97 (m, 3H, Ph), 3.76
(sept, J ) 6.9, 2H, CH(CH3)2), 3.23-3.18 (m, 1H, CH), 2.09-
2.04 (m, 2H, CH2), 1.51 (d, J ) 4.5, 3H, CHCH3), 1.26-1.00 (m,
8H, CH2), 1.25 (d, J ) 6.9, 12H, CH(CH3)2), 0.82 (t, J ) 5.5, 3H,
CH2CH3). 13C{1H} NMR (75.42 MHz, C6D6, 293 K, plus APT,
COSY, and HETCOR): δ 129.3, 128.9 (Cipso Ph), 128.5, 127.7
(Ph), 62.6 (CH), 32.6, 31.9, 28.9, (CH2), 28.8 (CH(CH3)2), 26.4

Half-Sandwich Alkyl-Titanium(IV) Complexes
Organometallics, Vol. 25, No. 17, 2006 4089
(Cipso Ph), 130.7, 125.9 (Ph), 65.7 (CH), 39.6 (CH Cy), 28.8,
25.9 (CH2), 20.7 (CH3), 20.2 (CHCH3). MS: m/z 231 (M+), 148
(M+ - Cy).
Hydroamination of Cyclohexylacetylene with Cyclohexyl-
amine. CyCH2CHdNCy: 1H NMR (300 MHz, C6D6, 293 K): δ
7.47 (t, J ) 6.0, 1H, CHd), 2.91-2.83 (m, 1H, CH Cy), 2.09-
2.05 (m, 2H, CH2CH), 1.81-0.85 (m, 21H, Cy). 13C{1H} NMR
(75.42 MHz, C6D6, 293 K, plus APT and HETCOR): δ 160.2
(CHd), 70.0 (CH Cy), 43.5 (CH2CH), 35.6 (CH Cy), 34.8, 33.3,
26.4, 24.8 (CH2 Cy). MS: m/z 207 (M+), 124 (M+ - Cy). CyC-
(CH3)dNCy: 1H NMR (300 MHz, C6D6, 293 K): δ 3.28-3.21
(m, 1H, CH Cy), 1.81-0.85 (m, 21H, Cy), 1.49 (s, 3H, CH3). 13C-
{1H} NMR (75.42 MHz, C6D6, 293 K, plus APT and HETCOR):
δ 168.4 (dC), 58.6, 35.6 (CH Cy), 34.2, 30.6, 26.7, 26.1, (CH2),
14.4 (CH3). MS: m/z 207 (M+), 192 (M+-CH3). CyCH2CH2-
NHCy: 1H NMR (300 MHz, C6D6, 293 K): δ 2.89-2.83 (m, 1H,
CH Cy), 2.80-2.63 (m, 4H, CH2), 2.10-0.82 (m, 21H, Cy). 13C-
{1H} NMR (75.42 MHz, C6D6, 293 K, plus APT, COSY, and
HETCOR): δ 62.0 (CH Cy), 49.2, 43.0 (CH2), 35.7 (CH Cy), 33.8,
28.7, 25.6, 22.6 (CH2). MS: m/z 209 (M+), 126 (M+ - Cy). CyCH-
(CH3)NHCy: 1H NMR (300 MHz, C6D6, 293 K): δ 2.89-2.83
(m, 1H, CH Cy), 2.80-2.70 (m, 1H, CHCH3), 2.10-0.82 (m, 21H,
Cy), 1.20 (d, J ) 5.1, 3H, CH3). 13C{1H} NMR (75.42 MHz, C6D6,
293 K, plus APT, COSY, and HETCOR): δ 57.2 (CH), 56.2, 36.0
(CH Cy), 33.2, 28.7, 25.6, 24.6 (CH2), 13.0 (CH3). MS: m/z 209
(M+), 194 (M+ - CH3).
Hydroamination of Cyclohexylacetylene with 2,6-Diisopropyl-
aniline. CyC(dCH2)NH-2,6-iPr2C6H3: 1H NMR (300 MHz, C6D6,
293 K): δ 7.18-6.95 (m, 3H, Ph), 4.05 (br s, 1H, NH), 3.69, 3.35
(both s, each 1H, dCH2), 3.28 (sept, J ) 6.9, 2H, CH(CH3)2), 1.92-
1.28 (m, 11H, Cy), 1.21 (d, J ) 6.9, 12H, CH(CH3)2). 13C{1H}
NMR (75.42 MHz, C6D6, 293 K, plus APT and HETCOR): δ 155.7
(Cd), 147.1, 136.4 (Cipso Ph), 127.3, 123.8 (Ph), 79.0 (dCH2), 44.7
(CH Cy), 32.4 (CH2 Cy), 28.2 (CH(CH3)2), 26.8 (CH2 Cy), 24.1
(CH(CH3)2). CyC(CH3)dN-2,6-iPr2C6H3: 1H NMR (300 MHz,
C6D6, 293 K): δ 7.18-6.95 (m, 3H, Ph), 2.88 (sept, J ) 6.9, 2H,
CH(CH3)2), 2.17-2.08 (m, 1H, CH), 1.95-1.41 (m, 10H, CH2),
1.39 (s, 3H, CH3), 1.20, 1.18 (d, J ) 6.9, each 6H, CH(CH3)2).
13C{1H} NMR (75.42 MHz, C6D6, 293 K, plus APT and HET-
COR): δ 167.1 (Cd), 147.1, 135.9 (Cipso Ph), 123.3, 123.2 (Ph),
48.7 (CH), 30.5 (CH2), 28.2 (CH(CH3)2), 26.3 (CH2), 23.1, 22.7
(CH(CH3)2). MS: m/z 285 (M+), 202 (M+ - Cy). CyCH(CH3)-
NH-2,6-iPr2C6H3: 1H NMR (300 MHz, C6D6, 293 K): δ 7.10-
6.80 (m, 3H, Ph), 3.60 (sept, J ) 6.9, 2H, CH(CH3)2), 3.10-2.97
(m, 1H, CH), 2.00-1.34 (m, 11H, Cy), 1.20 (d, J ) 6.9, 12H,
CHCH3), 0.98 (d, J ) 4.5, 3H, CH3). 13C{1H} NMR (75.42 MHz,
C6D6, 293 K, plus APT, COSY, and HETCOR): δ 136.4, 136.2
(Cipso Ph), 129.5, 128.1 (Ph), 67.7 (CH), 39.4 (CHCy), 34.8 (CH2),
28.2 (CH(CH3)2), 25.7 (CH2), 23.9 (CH(CH3)2), 12.3 (CHCH3).
MS: m/z 287 (M+), 204 (M+ - Cy).
Hydroamination of Cyclohexylacetylene with tert-Butylamine.
CyCH2CHdNtBu: 1H NMR (300 MHz, C6D6, 293 K): δ 7.49 (t,
J ) 4.8, 1H, CHd), 2.13-2.09 (m, 2H, CH2CH), 1.61-0.82 (m,
11H, Cy), 1.16 (s, 9H, C(CH3)3). 13C{1H} NMR (75.42 MHz, C6D6,
293 K, plus APT): δ 156.5 (CHd), 56.4 (C(CH3)3), 44.1 (CH2-
CH), 35.7 (CH Cy), 33.3 (CH2 Cy), 29.6 (C(CH3)3), 26.5, 26.4
(CH2 Cy). MS: m/z 181 (M+), 166 (M+ - CH3). CyCH2CH2-
NHtBu: 1H NMR (300 MHz, C6D6, 293 K): δ 8.80 (br s, 1H,
NH), 2.68, 1.82 (both m, each 2H, CH2), 1.67-0.84 (m, 11H, Cy),
1.28 (s, 9H, C(CH3)3). 13C{1H} NMR (75.42 MHz, C6D6, 293 K,
plus APT, COSY, and HETCOR): δ 59.6 (C(CH3)3), 39.9 (CH2),
35.5 (CH Cy), 33.7 (CH2), 33.0, 26.5, 25.8 (CH2 Cy), 25.4
(C(CH3)3). MS: m/z 183 (M+), 168 (M+ - CH3).
Hydroamination of Cyclohexylacetylene with Dodecylamine.
CyCH2CHdNCH2(CH2)10CH3: 1H NMR (300 MHz, C6D6, 293
K): δ 7.45 (t, J ) 4.8, 1H, CHd), 3.31 (t, J ) 6.7, 2H, NCH2),
2.05-2.00 (m, 2H, CH2CH), 1.53-1.01 (m, 31H, Cy + CH2), 0.86
(t, J ) 6.9, 3H, CH3). 13C{1H} NMR (75.42 MHz, C6D6, 293 K,
plus APT): δ 162.3 (CHd), 61.9 (NCH2), 43.6 (CH2CH), 35.7
(CH Cy), 33.3, 32.2, 31.3, 30.0, 29.9, 29.7, 29.6, 27.6, 26.5, 26.4
(CH2), 14.1 (CH3). MS: m/z 293 (M+), 278 (M+ - CH3). CyCH2-
CH2NHCH2(CH2)10CH3: 1H NMR (300 MHz, C6D6, 293 K): δ
9.0 (br s, 1H, NH), 2.80-2.68 (m, 4H, CH2), 2.65-2.58 (m, 2H,
CH2), 2.07-1.03 (m, 31H, Cy + CH2), 0.93-0.89 (m, 3H, CH3).
13C{1H} NMR (75.42 MHz, C6D6, 293 K, plus APT, COSY, and
HETCOR): δ 47.8, 47.4, 45.6 (CH2), 39.7 (CH Cy), 33.2, 32.4,
32.3, 30.2, 29.6, 28.7, 27.6, 27.1, 26.7, 26.4, (CH2), 14.4 (CH3).
MS: m/z 295 (M+), 280 (M+ - CH3).
Hydroamination of Phenylacetylene with Dodecylamine.
1
PhCHdCHNHCH2(CH2)10CH3: H NMR (300 MHz, C6D6, 293
K): δ 7.32-7.01 (m, 5H, Ph), 6.73 (dd, J ) 6.9, J ) 14.4, 1H,
dCHN), 5.43 (d, J ) 14.4, 1H, PhCHd), 3.40 (m, 2H, CH2), 2.85-
2.78 (m, 1H, NH), 1.50-1.20 (m, 20H, CH2), 0.96 (t, J ) 6.9, 3H,
CH3). 13C{1H} NMR (75.42 MHz, C6D6, 293 K, plus APT and
HETCOR): δ 137.5 (Cipso Ph), 135.6 (dCHN), 128.3, 127.0, 123.6
(Ph), 98.3 (PhCHd), 52.2, 44.3, 32.2, 31.5, 31.2, 28.0, 27.8, 22.9
(CH2), 14.2 (CH3). PhCH2CHdNCH2(CH2)10CH3: 1H NMR (300
MHz, C6D6, 293 K): δ 7.97-7.93 (m, 1H, Ph), 7.52 (t, J ) 5.1,
1H, CHdN), 7.32-7.01 (m, 4H, Ph), 3.48 (d, J ) 5.1, 2H, PhCH2),
3.35 (m, 2H, CH2), 1.50-1.20 (m, 20H, CH2), 0.96 (t, J ) 6.9,
3H, CH3). 13C{1H} NMR (75.42 MHz, C6D6, 293 K, plus APT
and HETCOR): δ 161.6 (CHdN), 140.6 (Cipso Ph), 129.3, 128.8,
123.9 (Ph), 61.5, 42.3 (CH2), 42.5 (PhCH2), 32.1, 29.9, 29.6, 27.3,
27.2, 22.9 (CH2), 14.2 (CH3). MS: m/z 287 (M+), 272 (M+ _ CH3).
PhCH2CH2NHCH2(CH2)10CH3: 1H NMR (300 MHz, C6D6, 293
K): δ 7.24-7.03 (m, 5H, Ph), 3.26-3.21 (m, 2H, CH2), 3.00-
2.90 (m, 2H, CH2), 2.73-2.64 (m, 2H, CH2), 1.40-1.13 (m, 20H,
CH2), 0.93 (t, J ) 7.0, 3H, CH3). 13C{1H} NMR (75.42 MHz, C6D6,
293 K, plus APT): δ 141.0 (Cipso Ph), 129.1, 128.6, 126.2 (Ph),
49.3, 48.1, 40.6, 32.4, 30.3-24.3, 27.1, 23.1 (CH2), 14.3 (CH3).
MS: m/z 289 (M+), 274 (M+ _ CH3).
Acknowledgment. Financial support from the MCYT of
Spain (Proyect CTQ2005-00656 and PPQ2000-0488-P4-02) is
acknowledged. A.C.M. thanks Repsol-YPF for a grant. M.L.B.
thanks the Spanish MCYT/Universidad de Zaragoza for funding
through the “Ramo´n y Cajal” program.
OM060370H