Hydro(trispyrazolyl)borato-ruthenium(II) diphosphinoamino complex-catalyzed addition of β-diketones to 1-alkynes and anti-markovnikov addition of secondary amines to aromatic 1-alkynes

Article abstract of DOI:10.1002/adsc.201000567

The hydro(trispyrazolyl)borato-ruthenium(II) diphosphinoamino complex TpRu[4-CF₃C₆H₄N(PPh₂) ₂](OTf) (I) [Tp=hydro(trispyrazolyl)borate] catalyzes the Markovnikov addition of β-diketones to unactivated 1-alkynes in good to excellent yields. The reaction proceeds under solvent-free and additive-free conditions and the catalyst loading can be reduced down to 0.4amol%. Complex I (1amol%) also catalyzes the addition of secondary amines to aromatic terminal alkynes, unusual anti-Markovnikov products are exclusively formed.

Full text of DOI:10.1002/adsc.201000567

FULL PAPERS
DOI: 10.1002/adsc.201000567
Hydro(trispyrazolyl)borato-Ruthenium(II) Diphosphinoamino
Complex-Catalyzed Addition of b-Diketones to 1-Alkynes and
Anti-Markovnikov Addition of Secondary Amines to Aromatic
1-Alkynes
Hung Wai Cheung,a Chau Ming So,a Kwok Hung Pun,a Zhongyuan Zhou,a
and Chak Po Laua,*
a
Department of Applied Biology & Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon,
Hong Kong, Peopleꢀs Republic of China
Fax : (+852)-2364-9932; e-mail: bccplau@polyu.edu.hk
Received: July 19, 2010; Revised: December 19, 2010; Published online: February 16, 2011
Abstract: The hydro(trispyrazolyl)borato-rutheniu- can be reduced down to 0.4 mol%. Complex I
m(II)
diphosphinoamino
complex
TpRu[4- (1 mol%) also catalyzes the addition of secondary
CF3C6H4N
N
ACHTUNGTRENNUNG
lyl)borate] catalyzes the Markovnikov addition of b- Markovnikov products are exclusively formed.
diketones to unactivated 1-alkynes in good to excel-
lent yields. The reaction proceeds under solvent-free Keywords: addition reaction; 1-alkynes; b-diketones;
and additive-free conditions and the catalyst loading ruthenium; secondary amines
Introduction
is required to suppress the by-product formation so as
to obtain the desired products in good yields.[3]
À
The addition of 1,3-dicarbonyl compounds to unacti-
Catalytic intra- and intermolecular additions of N
vated alkynes under neutral conditions without prior H bond to alkynes providing cyclic enamines/imines
enolate formation represents an attractive and atom and enamines/imines, respectively, are important or-
economical method for the formation of carbon- ganic transformations as the products are useful inter-
carbon bonds. The intramolecular addition reaction mediates for further synthetic elaboration; these pro-
was exemplified by the gold(I)-catalyzed Conia-ene cesses are highly atom-economical as no waste is gen-
reaction of b-keto esters with alkynes reported by erated.[5] The hydroamination of terminal alkynes pro-
Toste and co-workers; the reaction proceeds under vides additional challenges in terms of regioselectivity.
neutral conditions at room temperature.[1] Yang and A variety of metals including early, late transition
co-workers reported the NiACHTNUGTRENNUG(acac)2/YbACHTUNGTREN(NUGN OTf)3-cata- metals, lanthanides, and actinides are capable of cata-
À
lyzed intramolecular addition of acetylenic 1,3-dicar- lyzing the intermolecular addition of N H bonds to
bonyl compounds.[2] On the other hand, an intermo- terminal alkynes yielding Markovnikov products or
lecular version of the addition reaction catalyzed by mixtures of Markovnikov and anti-Markovnikov
indium triflate was reported by Nakamura and Naka- products.[6] On the other hand, highly regioselective
mura.[3] The rhenium complex [ReBr(CO)
3ACHTNUTRGNE(NUG THF)]2 catalytic systems generating anti-Markovnikov prod-
was found to be an active catalyst for both inter- and ucts are relatively rare. The organouranium complex
intramolecular addition reactions of 1,3-dicarbonyl Cp*2UMe2 was the first catalyst for the anti-Markov-
compounds with terminal acetylenes under mild con- nikov hydroamination of terminal alkynes with pri-
ditions.[4] These reported catalytic systems are, in gen- mary amines.[7] It was then learned that some titano-
eral, only efficient for the intramolecular and/or inter- cene derivatives catalyzed the anti-Markovnikov hy-
molecular addition of the b-keto esters to terminal al- droamination of terminal alkynes with bulky primary
kynes. In contrast, the intermolecular addition of the aliphatic amines.[8] Unlike the titanocene-based cata-
1,3-diketones to terminal alkynes requires harsh reac- lyst systems, the bisACTHNUTRGNEUNG(amidate)titanium complexes em-
tion conditions such as high catalyst loading, high ployed by Schafer for terminal alkyne hydroamina-
temperature, long reaction time, and large excess of tion demonstrate high regioselectivity in favor of anti-
alkynes; moreover, in some cases, addition of n-BuLi Markovnikov hydroamination of terminal alkynes
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Figure 1.
with primary alkylamines regardless of the steric bulk for the unusual anti-Markovnikov addition of secon-
in either the amine or the alkyne substrate.[9] The dary amines to aromatic terminal alkynes.
CsOH-catalyzed hydroamination of phenylacetylene
with substituted anilines and N-heterocycles was the
only known example of anti-Markovnikov addition of Results and Discussion
secondary amines to terminal alkynes until recently
when it was reported that TpRhACTHNUTRGNEG(UN C2H4)2/PPh3 catalyz- For the addition reactions of 1,3-dicarbonyl com-
es the anti-Markovnikov hydroamination of terminal pounds to 1-alkynes, a metal center with appropriate
alkynes with secondary amines as well as primary electrophilicity is generally required for the coordina-
ones.[10–11] We report here that a hydrotris(pyrazolyl)- tion and activation of the alkynes. We have been
borate ruthenium complex supported by a diphosphi- working with ruthenium complexes supported by hy-
noamine ligand is an excellent catalyst for the addi- drotris(pyrazolyl)borate (Tp) ligands for more than a
tion of b-diketones to 1-alkynes and is also effective decade; we therefore first studied the catalytic activity
of the TpRu complexes VI–VIII (Figure 1) for the ad-
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Hydro(trispyrazolyl)borato-Ruthenium(II) Diphosphinoamino Complex-Catalyzed Addition of b-Diketones
Table 1. TpRu(II) complexes-catalyzed addition of acetyl-
ACHTUNGTRENNUNG
acetone with phenylacetylene.[a]
(Scheme 1). Complexes I–V were found to be signifi-
cantly more active than VI–IX (entries 1–5, Table 1).
The solvent complexes II and IV exhibit lower cata-
lytic activity than the corresponding triflate com-
plexes I and III, respectively, probably due to the fact
that acetonitrile is a more strongly coordinating
ligand than the triflate. The complexes containing the
more electron-withdrawing 4-CF3C6H4NACHTNUTGRNEUG(N PPh2)2 ligand
(I and II) seem to be better catalysts than the ones
containing PNP ligands with a n-butyl substituent on
the phenyl ring (III and IV). Complex V shows much
lower catalytic activity in comparison to the analo-
gous triflate complex IV. The screening of catalytic
activity of the complexes for the addition reaction of
1a to 2a reveals that complex I is the most active cata-
lyst for the reaction and it was therefore chosen as
the catalyst for further study of the reaction depicted
in Eq. (1) in Table 2.
TpRu[4-CF3C6H4NACHTNUTRGNE(NUG PPh2)2]OTf (I)-Catalyzed
Addition of b-Diketones to 1-Alkynes
Table 2 shows the results of the I-catalyzed addition
of b-diketones to terminal alkynes. In general, we ob-
served complete conversion within 6 h when
0.4 mol% of I was used. Acetylacetone is alkenylated
with phenylacetylenes with excellent yields; substitu-
ents on the phenyl ring of the alkynes do not induce
pronounced electronic effects (entries 1–5, Table 2).
Aliphatic alkynes 2g–2j (entries 7–10, Table 2) and
the heterocyclic 3-ethynylthiophene 2f (entry 6,
[a]
[b]
Reaction conditions: catalyst (0.005 mmol), acetylacetone
(1.25 mmol), phenylacetylene (1.5 mmol); 1208C.
Conversion (based on acetylacetone) determined by
1H NMR spectroscopy.
dition of acetylacetone (1a) to phenylacetylene (2a). Table 2) are also active substrates. Bulky dibenzoyl-
These complexes, however, were found to be of very methane (1c) (entry 12, Table 2) and the unsymmetri-
low activity or inactive for the reaction (entries 6–8, cal diketones 1b and 1d (entries 11 and 13, Table 2)
Table 1). We then turned to the Tpm-supported Ru are also transformed to the corresponding products in
species (IX) [Tpm=tris(pyrazolyl)methane] which is good yields; prolonged heating is, however, required
dicationic and highly electrophilic, but only to find for 1c. It is worth noting that I is a more efficient cat-
that it is also inactive (entry 9, Table 1). The TpRu alyst than those previously reported for the addition
complexes I–IV (Figure 1) contain the amine-bridged of b-diketones to 1-alkynes in terms of catalyst load-
diphosphinoamine ligands. These ligands, which offer ing and turnover frequency. Furthermore, unlike
more opportunities for electronic and steric tuning many known catalytic addition reactions which are
than the dppm analogue, have played important roles plagued by dimer/oligomer side-products, no alkyne
in chromium-catalyzed ethylene trimerization and tet- dimers and/or oligomers were formed as side-product
ramerization reactions.[13] It has also been suggested in the I-catalyzed reactions; large excesses of the 1-al-
that the propensity for back-bonding by the diphos- kynes were not required for this catalytic system, only
phinoamine ligand is at least similar to, if not greater 1.2 equivalents of 1-alkyne relative to the b-diketones
than, that of the carbonyl group.[14] We therefore were sufficient to give the desired products in excel-
expect the electrophilicity of complexes I–IV to be lent yields. Moreover, addition of n-BuLi and a strong
higher than that of VI–VIII, but lower than that of base such as DBU or Et3N is not required in the cata-
the TpmRu species IX. We also included complex V lytic system. Furthermore, the I-catalyzed addition of
containing the N,N-bis(diphenylphosphinomethylene)- b-diketones to 1-alkynes can be performed under sol-
ACHTUNGTRENNUNGbutylamine ligand, which has a methylene group sepa- vent-free condition. It should, however, be pointed
rating the nitrogen and the phosphorus atoms. Com- out that attempted I-catalyzed addition reactions of
plexes I–V were prepared by ligand substitution of b-keto esters and b-keto diesters to phenylacetylenes
TpRu
ACHTUNGTRENNUNG(PPh3)2Cl and subsequent chloride removal with were not successful. Moreover, the attempted Conia-
Ag+OTfÀ in the absence or presence of acetonitrile ene reaction of 3-(pent-4-ynyl)pentane-2,4-dione (1e)
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Scheme 1.
gives a poor yield of the intramolecular addition nylidene complex {TpRu[4-CF3C6H5NACTHUNRTGENN(UG PPh2)2]ACHTUNGTRENNUNG(=C=
product (entry 14, Table 2).
CHPh)}+OTfÀ (Ia), a very minor signal (d=90.9 ppm)
attributable to the alkynyl species TpRu[4-CF3C6H5N-
ꢀ
(PPh2)2]
E
NMR Monitoring of the I-Catalyzed Addition of
Acetylacetone to Phenylacetylene
sity of this peak grew with time at the expense of that
of the signal of Ia; Ib became the dominant species
after 30 min; at this time a very minute signal due to
To gain more information on the possible reaction the
carbonyl
species
{TpRu[4-CF3C6H5N-
mechanism of the catalytic reaction, the I-catalyzed
AHCTUNGTRENNUNG
addition of acetylacetone to phenylacetylene was 80.6 ppm. Compound Id was probably formed via a
monitored by NMR spectroscopy. Several solutions reaction sequence outlined in Scheme 2; the reaction
prepared from the same mother solution containing I sequence is similar to that proposed by Bianchini et
and the substrates were heated in sealed tubes in the al.,
same oil bath at 1208C. The tubes were removed PrN(CH2CH2PPh2)2Ru
from the oil bath at different times; an aliquot was acetylene and water led to quantitative formation of
who
found
that
reaction
of
n-
AHCTUNTGREG(NUNN PPh3)Cl2 with excess phenyl-
AHCTUNGTRENNUNG
taken from each tube and studied by NMR spectros- the carbonyl species n-PrN(CH2CH2PPh2)2Ru(CO)Cl2,
copy. Figure 1 shows the 31P{1H} NMR spectra of the with one equivalent of toluene formed as by-prod-
samples which had been heated for different periods uct.[15] The important step for the formation of Id is
of time, the column at the right shows the percent the nucleophilic attack of H2O at the a-carbon of the
conversions to the product. The 31P{1H} NMR spec- vinylidene moiety of Ia. However, the NMR monitor-
trum (in benzene-d6) of the sample after 5 min of ing experiment (Figure 2) shows that Id only started
heating showed a signal at d=75.9 ppm due to the vi- to appear after most of Ia had disappeared and the
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Hydro(trispyrazolyl)borato-Ruthenium(II) Diphosphinoamino Complex-Catalyzed Addition of b-Diketones
(OTf) (I)-catalyzed addition of b-diketones to 1-alkynes.[a]
Table 2. TpRu[4-CF3C6H4NACHTNUGRTENNUG(PPh2)2]CAHTUNGTRENNUGN
[a]
Reaction conditions: catalyst (0.005 mmol), dicarbonyl compound (1.25 mmol), terminal alkyne (1.5 mmol); 1208C.
Isolated yield (based on b-diketone).
Under 10 bar Ar.
[b]
[c]
[d]
Catalyst (0.03 mmol), 1e (1 mmol).
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Scheme 2.
signal of the former continues to gain abundance species throughout the catalytic process and it was
even after the signal of the latter had totally vanished. probably generated via deprotonation of the vinyli-
This phenomenon is only explainable in terms of the dene complex Ia. Since no base was added to the re-
presence of a very minute and NMR undetectable action mixture, we suspect that adventitious water in
amount of Ia in the system throughout the catalytic the substrates, which were not dried, might be the re-
process (vide infra).
The 31P{1H} NMR monitoring showed that the al- Ib and H3O+OTfÀ. We therefore treated the acetyl-
kynyl complex Ib was the dominant metal-containing acetone and phenylacetylene with 4 ꢂ molecular
agent that deprotonated the vinylidene species to give
AHCTUNGTRENNUNG
Figure 2. 31P{1H} NMR study of TpRu[4-CF3C6H4N
ACHTNUTRGENNU(G PPh2)2]HCATUNGTREN(NGUN OTf) (I)-catalyzed addition of acetylacetone to phenylacetylene.
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Hydro(trispyrazolyl)borato-Ruthenium(II) Diphosphinoamino Complex-Catalyzed Addition of b-Diketones
sieves and repeated the 31P{1H} NMR montoring ex- dependently prepared Ib was found to be inactive for
periment with these ꢃdriedꢀ substrates. The NMR the addition reaction; however, upon addition of
study showed that with the ꢃdriedꢀ substrates, the dis- 1 equivalent of H3O+OTfÀ, it became active, showing
appearance and the growing in of Ia and Ib, respec- a catalytic activity similar to that of I. It can be seen
tively, took place in a much slower pace; the latter from the NMR monitoring experiment shown in
only became the dominant species after nearly 2 h. It Figure 3 that upon addition of 1 equivalent of
is also noteworthy that only 27% conversion was ob- H3O+OTfÀ at room temperature, Ib was immediately
tained with the ꢃdriedꢀ substrates after 3 h, whereas converted to Ia. However, after heating at 1208C for
with ꢃundriedꢀ substrates gave 89% conversion. The 30 min, Ib reappeared and it became the dominant
data seem to support the notion that adventitious species throughout the monitoring experiment. The
water in the system deprotonates 1a to form 1b and monitoring experiment was carried out with a proce-
the conjugated acid H3O+OTfÀ.
dure similar to that for the NMR monitoring experi-
ments mentioned in previous sections. To eliminate
the possibility of the reaction being catalyzed by the
HOTf or H3O+OTf, we attempted the addition reac-
tion of acetylacetone to phenylacetylene in the ab-
sence of complex I but with addition of 1 equivalent
of HOTf (relative to the amount of I used in catalytic
NMR Monitoring of Addition of Acetylacetone to
Phenylacetylene Catalyzed by TpRu[4-
+
À
ꢀ
CF3C6H4NACHTUNGTRENNUNG(PPh2)2]ACHTUNGTREN(NGUN C CPh) (Ib)/H3O OTf
The alkynyl complex Ib, which seems to be the resting reactions reported in Table 2); however, no yield
state of the I-catalyzed addition of acetylacetone to could be obtained after heating at 1208C for 24 h.
phenylacetylene, was independently prepared. This in-
Figure 3. 31P{1H} NMR study of TpRu[4-CF3C6H4N
ACTHNUGTRNE(NUNG PPh2)2]CAHTUNGTRENN(UGN C CPh) (Ib)-catalyzed addition of acetylacetone to phenylacety-
lene.
ꢀ
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The same result was obtained using H3O+OTfÀ in
place of HOTf.
When the observations of the NMR monitoring ex-
periments are taken together, it seems that at room
temperature H3O+OTfÀ readily protonates Ib to form
Ia, probably via tautormerization of the h2-alkyne
2
ꢀ
complex
TpRu[4-CF3C6H4N
G
(Ic), which is the kinetic product of protonation of Ib;
however, at 1208C, the reversed reaction, that is, de-
protonation of Ia by water to generate Ib, dominates.
We suggest that in the course of catalysis (at 1208C), Proposed Mechanism for the I-Catalyzed Addition of
the conjugated acid H3O+OTfÀ formed via deprotona- b-Diketones to 1-Alkynes
tion of Ia with water, might have reacted with other
species present in the catalytic system and form a new The regioselectivity of the addition reaction shows
acidic species of diminished acidity; its ability to pro- that the Markonikov product could not be formed via
tonate 1b is low so that the amount of Ia regenerated attack of the b-diketone at the vinylidene moiety of
via this process is so small that it is not detectable Ia or the alkynyl group of Ib; on the other hand, reac-
with 31P{1H} NMR spectroscopy. It was previously re- tion of b-diketone with the tautomer of Ia, the h2-
2
ꢀ
ported that in FSO3H, H2SO4, or dilute FSO3H-SbF3- alkyne complex TpRu[4-CF3C6H4N
(PPh2)2](h -HC
SO2 solution, the b-diketone is monoprotonated to CPh) (Ic) could yield the the Markonikov addition
give a monocation having the structure A, which was product. The h2-alkyne complex Ic has, however,
1
observed by H NMR spectroscopy [Eq. (2)].[16]
never been observed in the NMR monitoring experi-
Theoretical calculations for protonated acetylace- ments. Scheme 3 shows a proposed mechanism for the
tone revealed that the ion containing an intramolecu- addition reaction (using acetylacetone and phenylace-
lar hydrogen bond (cyclic structure B) is the low tylene as model substrates). We are of the opinion
energy conformation.[16] We suggested that the acid that a combination of Ib and HDK+ might have con-
H3O+OTfÀ might have been trapped by the b-dike- stituted an active system for the addition reaction.
tone to form an adduct (HDK+), the structure of HDK+ might, to a very small degree, partially proton-
which we cannot predict.
ate Ib to generate a very minute and NMR-undetecta-
ble amount of h2-alkyne tautomer Ic; it is immediate-
ly attacked, prior to its tautormierization to the vinyli-
Scheme 3.
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Hydro(trispyrazolyl)borato-Ruthenium(II) Diphosphinoamino Complex-Catalyzed Addition of b-Diketones
dene species Ib, by the b-diketone or its enol form that the I-catalyzed addition of b-diketones to 1-al-
which originates from HDK+ and is in close proximity. knyes is a good alternative for the existing catalytic
For ruthenium, it is common knowledge that the h1- processes. Complex I is also capable of catalyzing the
vinylidene species is thermodynamically more stable unusual anti-Markovnikov addition of secondary
than the h2-alkyne complex.[17] A recent kinetic study amines to terminal alkynes. It is very interesting to
with indenylruthenium species supports the hypothe- note that the I-catalyzed addition of b-diketones to 1-
sis that the h2-alkyne tautomer is formed under transi- alkynes follows the Markovnikov addition pattern,
ent conditions and tautomerizes readily to the h1-vi- while the regioselectivity of the hydroamination of 1-
nylidene complex.[18]
alkynes is exclusively anti-Markovnikov. More inter-
estingly, the two reactions seem to have an identical
catalyst resting state, that is, a ruthenium alkynyl spe-
cies Ib. To account for the regioselectivities of the ad-
dition reactions, we proposed that in the addition of
b-diketones to 1-alkynes, the active species is the
ruthenium h2-alkyne complex; on the other hand, in
TpRu[4-CF3C6H4NACHTNUTRGNE(NUG PPh2)2]OTf (I)-Catalyzed
Addition of Secondary Amines to Aromatic 1-
Alkynes
Besides the catalytic addition of b-diketones to termi- the hydroamination reactions, generation of the anti-
nal alkynes, we found that I is also an effective cata- Markovnikov product is more likely due to nucleo-
lyst for the hydroamination of terminal alkynes. Sev- philic attack of the vinylidene complexes by the
eral amines are used to screen the feasibility of the I- amine. Both complexes are transient species in the
catalyzed hydroamination reactions. It was found that course of the catalytic reactions.
only secondary amines are active, reactions with pri-
mary amine failed. Diethylamine, pyrrolidine, and pi-
peridine added to phenylacetylene to give products in
moderate yields. However, the bulky and less nucleo-
Experimental Section
philic diphenylamine gives no product yield. Substitu-
ents on the phenylacteylene do not seem to have
Materials and Instrumentation
much effect on the conversions. It is noteworthy that All manipulations were carried out under a nitrogen atmos-
phere using standard Schlenk techniques. Solvents were
freshly distilled under nitrogen from sodium-benzophenone
(tetrahydrofuran), sodium (diethyl ether, hexane and tolu-
ene), calcium hydride (dichloromethane, chloroform and
acetonitrile), magnesium-iodine (methanol and ethanol) or
P2O5 (C6D6 and CDCl3); they were degassed prior to use.
Elemental analyses were performed by M-H-W Laborato-
the I-catalyzed hydroamination reactions are highly
selective, the anti-Markovnikov products in trans
forms are formed exclusively; moreover, catalyst
loadings in our reactions are much lower than those
used in the other two catalytic reactions previously re-
ported.[10,11]
ꢀ
1
We monitored the hydroamination of alkyne (PhC
ries, Phoenix, AZ (USA). H NMR spectra were obtained
from a Bruker DPX-400 spectrometer at 400.13 MHz;
CH/Et2NH) with 31P{1H} NMR spectroscopy. After
heating the reaction mixture for 5 min, it was shown
chemical shifts (d, ppm) are reported relative to residual
by 31P{1H} NMR spectroscopy that about two thirds of peaks of the deuterated solvents used. 13C{1H} NMR spectra
were recorded with a Bruker DPX-400 spectrometer at
100.61 MHz; chemical shifts were internally referenced to
CDCl3 (d=77.7 ppm), C6D6 (d=128.1 ppm) or (CD3)2CO
(d=206.26, 29.84 ppm). 31P{1H} NMR spectra were recorded
on a Bruker DPX-400 spectrometer at 161.70 MHz; chemi-
cal shifts were externally referenced to 85% H3PO4 in D2O
(d=0.00 ppm). 19F NMR spectra were recorded on a Varian
Inova AS 500 NMR spectrometer at 470.22 MHz; chemical
shifts were externally referenced to trifluorotoluene in C6D6
(d=À62.5 ppm). All spectra were obtained at ambient
I was converted to the alkynyl complex Ib, and com-
plete conversion to the latter was observed after heat-
ing for 3 h. Complex Ib remained the only ruthenium
species detected throughout the monitoring period
(24 h). At this stage, it is difficult to speculate on the
possible mechanism of the I-catalyzed hydroamina-
tion reaction; however, the regioselectivity of the re-
action seems to suggest that the vinylidene species Ia
might be an important though transient intermediate
in the reaction since nucleophilic attack of the amine probe temperature unless stated otherwise. High-pressure
NMR studies were carried out in commercial 5 mm Wilmad
pressure-valved NMR tubes. Infrared spectra were obtained
from a Bruker Vector 22 FT-IR spectrophotometer. Mass
spectrometry was carried out with a Finnigan MAT 95S
mass spectrometer with the samples dissolved in dichloro-
methane or acetone. HR-MS was carried out with a Waters
Micromass Q-Tof-2. The ligands N,N-bis(diphenylphosphi-
at the a-carbon of the vinylidene moiety would most
likely lead to the formation of the anti-Markovnikov
product.
Conclusions
no)butylamine [n-BuN
nomethylene)butylamine [n-BuN
complexes TpRu
(PPh3)2Cl,[21] [TpRu
(PPh3)2A
(CH3CN)]+BF4
ACHTUNGTRENNUNG
We have found that a TpRu complex supported by a
diphosphinoamine ligand is an excellent catalyst for
AHCTUNGTRENNUNG
À
N
2A
(VII),[23] [TpRu-
À
the addition of b-diketones to 1-alknyes. We believe (IV),[22] [TpRu
U
CHTUNGTRENNUNG
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A
E
ACHTUGNRTEN(NUGN PPh3)2
TpRuACHTUNTRGENNUG[n-BuNACHTUNGTRNEN(GUN CH2PPh2)2]Cl
(CH3CN)]2+ (BF4 )2 (XI)[24] were prepared according to lit-
À
A procedure similar to that for the synthesis of TpRu[4-
CF3C6H4N(PPh2)2]Cl was followed, except that n-BuN-
(CH2PPh2)2 (1.2 g, 2.5 mmol) was used in place of 4-
CF3C6H4N(PPh2)2. Yellow solid; yield: 1.19 g (63%); anal.
calcd. (%) for C39H43BClN7P2Ru: C 57.19, H 5.29, N 11.97;
found: C 57.03, H 5.34, N 11.85; IR (KBr) :n(B
erature methods.
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
4-(Trifluoromethyl)-N,N-bis(diphenylphosphino)-
benzeneamine [4-CF3C6H4N(PPh2)2]
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
=
À
H)
To a stirred solution of 4-(trifluoromethyl)aniline (0.63 mL,
5.0 mmol) in toluene (40 mL), NEt3 (5 mL) was added, fol-
lowed by dropwise addition of Ph2PCl (2.0 mL, 11 mmol).
After complete addition, the mixture was heated at 808C
for 16 h. At the end of this period, the solution was cooled
to room temperature and the insoluble material was filtered
out. The solvent of the filtrate was evaporated under re-
duced pressure and a white paste was obtained. Pre-cooled
hexane (5 mL) was added to the residue, with stirring, to
produce a white solid. The solid was filtered out and dried
under vacuum at room temperature; yield: 1.27 g (48%).
1H NMR (400.13 MHz, C6D6, 258C): d=7.74–7.70 (m, 8H),
7.28–7.27 (m, 12H), 7.20–7.17 (m, 4H); 31P{1H} NMR
(161.7 MHz, C6D6, 258C): d=68.62 (s).
2459 cmÀ1 (br); H NMR (400.13 MHz, C6D6, 258C): d=8.45
(m, 4H, PPh2-H), 7.64 (s, 2H, Tp-H), 7.59 (s, 2H, Tp-H),
7.34 (d, 1H, Tp-H), 7.19–7.30 (m, 6H, PPh2-H), 6.88–6.94
(m, 10H, PPh2-H), 5.84 (s, 2H, Tp-H), 5.73 (d, 1H, Tp-H),
5.04 (t, 1H, Tp-H), 3.86 (m, 2H, -NCH2-), 3.63 (m, 2H,
PPh2PCH2-), 2.56 (t, 2H, PPh2PCH2-), 1.36 (m, 2H,
-NCH2CH2-), 1.23 (m, 2H, -NCH2CH2CH2-), 0.94 (t, 3H,
-NCH2CH2CH2CH3); 31P{1H} NMR (161.7 MHz, C6D6,
258C): d=34.82 (s); ESI-MS: m/z=819, [M]+.
1
TpRu[4-CF3C6H4NACHTNURGTENN(UG PPh2)2]CAHUTNGTRENN(GUN OTf) (I)
To the complex TpRu[4-CF3C6H4NACHTNUGTRNEUNG(PPh2)2]Cl (1.0 g,
1.14 mmol) and silver triflate (0.36 g, 1.4 mmol) was added
freshly degassed THF (20 mL); the resulting mixture was re-
fluxed with stirring for 4 h. At the end of this period, the
mixture was cooled to room temperature and evaporated to
dryness under reduced pressure. The residue was extracted
with dichloromethane (2ꢄ10 mL). The insoluble material
was filtered out. The solvent of the filtrate was removed
under reduced pressure and a yellow paste was obtained.
Hexane (5 mL) was added to the residue, with stirring, to
produce a yellow solid. The solid was filtered out and
washed with hexane/ethanol (1:1, 2ꢄ10 mL). It was then
collected and dried under vacuum at room temperature;
TpRu[4-CF3C6H4NACHTUNTRGNEU(GN PPh2)2]Cl
The complex TpRu
ACHTUGNRTEN(NUGN PPh3)2Cl (2.0 g, 2.3 mmol) and the
ligand 4-CF3C6H4N(PPh2)2 (1.3 g, 2.5 mmol) were dissolved
ACHTUNGTRENNUNG
in freshly degassed toluene (20 mL); the resulting solution
was refluxed with stirring for 4 h. At the end of this period,
the solution was cooled to room temperature and evaporat-
ed to dryness under reduced pressure to yield a pale yellow
paste. Hexane (15 mL) was added to the residue, with stir-
ring, to produce a pale yellow solid. The solid was filtered
out and washed with diethyl ether (2ꢄ10 mL). It was col-
lected and dried under vacuum at room temperature; yield:
1.47 g (73%); anal. calcd. (%) for C40H34BClF3N7P2Ru: C
yield:
0.81 g
(72%);
anal.
calcd.
(%)
of
C41H34BF6N7O3P2RuS: C 49.61, H 3.45, N 9.88; found: C
49.80, H 3.57, N 9.60; IR (KBr): n(B H) =2468 cmÀ1 (br);
À
54.66, H 3.90, N 11.15; found: C 54.61, H 3.97, N, 11.03; IR
1H NMR [400.13 MHz, (CD3)2CO, 258C]: d=8.08 (s, 2H,
Tp-H), 7.99–7.98 (m, 4H, PPh2-H), 7.70–7.69 (m, 6H, PPh2-
H), 7.67 (d, 1H, Tp-H), 7.52 (d, 2H, 4-CF3C6H4N-), 7.46–
7.45 (m, 6H, PPh2-H), 7.32–7.30 (m, 4H, PPh2-H), 7.21 (d,
2H, 4-CF3C6H4N-), 6.99 (s, 2H, Tp-H), 6.33 (d, 2H, Tp-H),
5.20 (d, 1H, Tp-H), 5.19 (t, 1H, Tp-H); 31P{1H} NMR
[161.7 MHz, (CD3)2CO, 258C]: d=85.90 (s); ESI-MS: m/z=
844.22 [MÀOTf]+.
1
(KBr): n(B H) =2486 cmÀ1 (br); H NMR (400.13 MHz, C6D6,
À
258C): d=8.44–8.47 (m, 4H, PPh2-H), 7.82 (s, 2H, Tp-H),
7.59–7.62 (m, 4H, PPh2-H), 7.54 (d, 2H, Tp-H), 7.43 (d, 1H,
Tp-H), 7.28–7.32 (m, 4H, PPh2-H), 7.30 (d, 2H, 4-
CF3C6H4N-), 7.16 (d, 2H, 4-CF3C6H4N-), 6.94–6.96 (m, 4H,
PPh2-H), 6.81–6.85 (m, 4H, PPh2-H), 5.94 (s, 2H, Tp-H),
5.36 (d, 1H, Tp-H), 5.22 (t, 1H, Tp-H); 31P{1H} NMR
(161.7 MHz, C6D6, 258C): d=88.80 (s); ESI-MS: m/z=
879.02, [M]+.
(PPh2)2]CH3CN}+OTfÀ (II)
ACHUNTRGEN{NUG TpRu[4-CF3C6H4NACHUTNGTRENNGUN
TpRuACHTUNGTRENNUNG[n-BuNACHTUNGTRENNUNG(PPh2)2]Cl
THF/acetonitrile (20:1, 20 mL) was added to the complex
TpRu[4-CF3C6H4N(PPh2)2]Cl (1.0 g, 1.14 mmol) and silver
A procedure similar to that for the synthesis of TpRu[4-
CF3C6H4N(PPh2)2]Cl was followed, except that n-BuN-
(PPh2)2 (1.1 g, 2.5 mmol) was used in place of 4-CF3C6H4N-
(PPh2)2. Yellow solid; yield: 1.29 g (72%); anal. calcd. (%)
ACHTUNGTRENNUNG
U
triflate (0.36 g, 1.4 mmol); the resulting mixture was re-
fluxed with stirring for 4 h. At the end of this period, the
mixture was cooled to room temperature and evaporated to
dryness under reduced pressure. The residue was extracted
with dichloromethane (2ꢄ10 mL). The insoluble material
was filtered out. The solvent of the filtrate was removed
under reduced pressure and a yellow paste was obtained.
Hexane (5 mL) was added to the residue, with stirring, to
produce a yellow solid. The solid was filtered out and
washed with hexane/ethanol (1:1, 2ꢄ10 mL). It was then
collected and dried under vacuum at room temperature;
ACHTUNGTRENNUNG
ACHTUNGTRENNUNG
for C37H39BClN7P2Ru: C 56.18, H 4.97, N 12.39; found: C
55.96, H 5.05, N 12.17; IR (KBr): n(B H) =2462 cmÀ1 (br);
À
1H NMR (400.13 MHz, CDCl3, 258C): d=8.04–8.05 (m, 4H,
PPh2-H), 7.68 (s, 2H, Tp-H), 7.62 (s, 2H, Tp-H), 7.39–7.44
(m, 6H, PPh2-H), 7.38 (d, 1H, Tp-H), 7.19–7.23 (m, 6H,
PPh2-H), 7.09–7.11 (m, 4H, PPh2-H), 6.14 (s, 2H, Tp-H),
5.81 (d, 1H, Tp-H), 5.17 (t, 1H, Tp-H), 3.44 (m, 2H,
-NCH2-), 1.44 (m, 2H, -NCH2CH2-), 1.01 (m, 2H,
-NCH2CH2CH2-), 0.67 (t, 3H, -NCH2CH2CH2CH3);
31P{1H} NMR (161.7 MHz, CDCl3, 258C): d=82.97 (s); ESI-
MS: m/z=791, [M]+.
yield:
0.77 g
(66%);
anal.
calcd
(%)
for
C43H37BF6N8O3P2RuS: C 49.96, H 3.61, N 10.84; found: C
49.60,
H
3.71,
N
10.56; IR (KBr): n(B H) =2487 (br);
À
420
asc.wiley-vch.de
ꢁ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2011, 353, 411 – 425

Hydro(trispyrazolyl)borato-Ruthenium(II) Diphosphinoamino Complex-Catalyzed Addition of b-Diketones
1H NMR (400.13 MHz, CD3CN, 258C): d=7.89 (s, 2H, Tp-
H), 7.83–7.84 (m, 4H, PPh2-H), 7.74 (s, 2H, Tp-H), 7.72–
7.74 (m, 4H, PPh2-H), 7.56 (d, 1H, Tp-H), 7.41 (t, 4H,
PPh2-H), 7.28 (q, 4H, PPh2-H), 7.13–7.27 (m, 4H, PPh2-H),
7.13–7.27 (m, 4H, 4-CF3C6H4N-), 6.32 (t, 2H, Tp-H), 5.31
(d, 1H, Tp-H), 5.20 (t, 1H, Tp-H), 2.07 (s, 3H, NCCH3);
31P{1H} NMR (161.7 MHz, CD3CN, 258C): d=87.05 (s);
ESI-MS: m/z=885 [M]+.
-NCH2CH2CH2CH3); 31P{1H} NMR (161.7 MHz, CDCl3,
+
À
258C): d=31.01 (s); ESI-MS: m/z=825 [M] ; 784 [M
NCCH3]+
Preparation of Complexes Ia, Ib and Id
The vinylidene complex Ia was readily prepared by reacting
I with excess phenylacetylene in chloroform at 608C. The
most relevant spectroscopic feature of Ia is the characteristic
deshielded 13C{1H} NMR signal for the a-carbon of the vi-
nylidene moiety at d=375.7 ppm; the Cb resonance falls
within the aromatic region and is therefore masked by a
large number of signals. The vinylidene proton of Ia can be
TpRuACHTUNGTRENNUNG[n-BuNACHTUNGTRENNUNG(PPh2)2]ACHTNUGTRNE(NUGN OTf) (III)
A procedure similar to that for the synthesis of TpRu[4-
CF3C6H4N(PPh2)2]OTf was followed, except that TpRu[n-
BuN(PPh2)2]Cl (0.90 g, 1.14 mmol) was used in place of
TpRu[4-CF3C6H4N(PPh2)2]Cl. Yellow solid; yield: 0.84 g
A
ACHTUNGTRENNUNG
1
readily identified as a triplet at d=4.51 ppm in the H NMR
ACHTUNGTRENNUNG
spectrum. 31P{1H} NMR spectroscopy shows a singlet at d=
75.9 ppm, which is consistent with the chemical equivalence
of the two phosphorus atoms of the diphosphinoamine
ligand. Similar to other reported diphosphinoamino com-
plexes, the 31P NMR signal of Ia is considerably deshielded
compared to that of the free ligand. Complex Ib was con-
veniently prepared by deprotonation of Ia with NaOH in
ethanol. The Ca of the alkynyl moiety appear as a triplets at
d=121.6 ppm (JCP =30 Hz) in the 13C{1H} NMR spectrum.
31P{1H} NMR spectroscopy shows a singlet at d=90.7 ppm
attributable to the equivalent phosphorus atoms. Complex
Id, although it is obtainable via reaction of Ia with water,
was prepared more conveniently by an alternative method –
reaction of I with pressurized CO. Complex Id is conven-
iently characterized by NMR and IR spectroscopy:
13C{1H} NMR, a singlet, which is due to the carbonyl carbon,
is detected at d=201.1 ppm; 31P{1H} NMR, a singlet corre-
sponding to the equivalent phosphorus atoms of the diphos-
phinoamine ligand, is seen at d=80.7 ppm; IR spectroscopy
ACHTUNGTRENNUNG
(67%); anal. calcd. (%) for C38H39BF3N7O3P2RuS: C 50.45,
H 4.35, N 10.84; found: C 50.19, H 4.41, N 10.61; IR (KBr):
n(B H) =2478 cmÀ1 (br); 1H NMR (400.13 MHz, CDCl3,
À
258C): d=7.77 (d, 2H, Tp-H), 7.74 (m, 4H, PPh2-H), 7.62
(s, 2H, Tp-H), 7.47–7.53 (m, 6H, PPh2-H), 7.28 (t, 2H,
PPh2-H), 7.17 (s, 1H, Tp-H), 7.11–7.17 (m, 8H, PPh2-H),
6.21 (s, 2H, Tp-H), 5.82 (s, 1H, Tp-H), 5.13 (s, 1H, Tp-H),
3.50 (m, 2H, -NCH2-), 1.52 (m, 2H, -NCH2CH2-), 1.06 (m,
2H, -NCH2CH2CH2-), 0.70 (t, 3H, -NCH2CH2CH2CH3);
31P{1H} NMR (161.7 MHz, CDCl3, 258C): d=83.32 (s); ESI-
MS: m/z=755, [MÀOTf]+.
ACHTUNGTRENNUNG{TpRuACHTUNGTRENNUNG[n-BuNACHTUNGTRENNUNG
(PPh2)2]CH3CN}+OTfÀ (IV)
A procedure similar to that for the synthesis of {TpRu[4-
CF3C6H4N
(PPh2)2]CH3CN]+OTfÀ was followed, except that
TpRu[n-BuN(PPh2)2]Cl (0.90 g, 1.14 mmol) was used in
place of TpRu[4-CF3C6H4N(PPh2)2]Cl. Yellow solid; yield:
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
shows the u(C
absorption at 1995 cmÀ1. Complexes I, Ia,
0.81 g (69%); anal. calcd. (%) for C40H42BF3N8O3P2RuS: C
50.80, H 4.48, N 11.85; found: C 50.64, H 4.60, N 11.65; IR
ꢀ
O)
Ib and Id were subject to X-ray diffraction studies. CCDC
755811 (I), CCDC 755812 (Ia), CCDC 755813 (Ib) and
CCDC 755814 (Id) contain the supplementary crystallo-
graphic data for the compounds of this paper. These data
can be obtained free of charge from The Cambridge Crystal-
lographic Data Centre via www.ccdc.cam.ac.uk/data_
request/cif.
(KBr): n(B H) =2495 cmÀ1 (br); 1H NMR (400.13 MHz,
À
CDCl3, 258C): d=7.79 (s, 2H, Tp-H), 7.59–7.68 (m, 10H,
PPh2-H), 7.59–7.68 (d, 1H, Tp-H), 7.34 (t, 2H, PPh2-H),
7.23 (s, 2H, Tp-H), 7.12–7.16 (m, 4H, PPh2-H), 7.02–7.03
(m, 4H, PPh2-H), 6.28 (d, 1H, Tp-H), 6.24 (s, 2H, Tp-H),
5.49 (t, 1H, Tp-H), 3.74 (m, 2H, -NCH2-), 2.09 (s, 3H,
NCCH3), 1.63 (m, 2H, -NCH2CH2-), 1.22 (m, 2H,
-NCH2CH2CH2-), 0.81 (t, 3H, -NCH2CH2CH2CH3);
31P{1H} NMR (161.7 MHz, CDCl3, 258C): d=83.81 (s). ESI-
MS: m/z=797 [M]+.
(=C=CHPh)]+OTfÀ (Ia)
AHCTUNTGERUNG{NN TpRu[4-CF3C6H4NAHCTUNRTGEG(NNUN PPh2)2]ACHTNUGTRENNGUN
The
complex
TpRu[4-CF3C6H4N
G
(0.5 g,
0.5 mmol) was dissolved in freshly degassed chloroform
(10 mL) and treated with 3 equiv. of phenylacetylene
(0.16 mL, 1.50 mmol). The resulting solution was heated at
608C for 16 h. At the end of this period, the solution was
cooled to room temperature and evaporated to dryness
under reduced pressure to yield a pink paste. Hexane
(5 mL) was added to the residue, with stirring, to produce a
pink solid. The solid was filtered out and washed with
hexane/ethanol (3:2, 2ꢄ5 mL). It was collected and dried
under vacuum at room temperature; yield: 0.43 g (78%);
anal. calcd. (%) for C49H40BF6N7O3P2RuS: C 53.76, H 3.68,
ACHTUNGTRENNUNG{TpRuACHTUNGTRENNUNG[n-BuNACHTUNGTRENNUNG
(CH2PPh2)2]CH3CN}+OTfÀ (V)
A procedure similar to that for the synthesis of {TpRu[4-
CF3C6H4N
(PPh2)2]CH3CN}+OTfÀ was followed, except that
TpRu[n-BuN(CH2PPh2)2]Cl (0.90 g, 1.14 mmol) was used in
place of TpRu[4-CF3C6H4N(PPh2)2]Cl. Yellow solid; yield:
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
0.73 g (61%); anal. calcd. (%) for C42H46BF3N8O3P2RuS: C
51.81, H 4.76, N 11.51; found: C 51.88, H 4.88, N 11.26; IR
(KBr): n(B H) =2484 cmÀ1 (br); 1H NMR (400.13 MHz,
À
CDCl3, 258C): d=7.90 (d, 1H, Tp-H), 7.84 (s, 2H, Tp-H),
7.67 (m, 4H, PPh2-H), 7.52–7.58 (m, 4H, PPh2-H), 7.33–7.47
(m, 2H, PPh2-H), 7.21 (t, 2H, PPh2-H), 7.19 (s, 2H, Tp-H),
6.96 (t, 4H, PPh2-H), 6.92 (d, 1H, Tp-H), 6.35 (m, 4H,
PPh2-H), 6.11 (s, 2H, Tp-H), 5.79 (t, 1H, Tp-H), 4.11 (m,
2H, -NCH2-), 3.34 (m, 2H, PPh2PCH2-), 3.04 (t, 2H,
PPh2PCH2-), 1.65 (m, 2H, -NCH2CH2-), 1.56 (s, 3H,
NCCH3), 1.40 (m, 2H, -NCH2CH2CH2-), 0.97 (t, 3H,
N 8.96; found: C 53.64, H 3.79, N 8.84; IR (KBr): n(B
=
À
H)
2486 (br), n(C C) =1663 cmÀ1 (s); 1H NMR (400.13 MHz,
=
CDCl3, 258C): d=7.83 (s, 2H, Tp-H), 7.79–7.80 (m, 4H,
PPh2-H), 7.64 (t, 3H, PPh2-H), 7.50 (s, 2H, Tp-H), 7.48 (s,
1H, Tp-H), 7.46–7.50 (m, 4H, PPh2-H), 7.39 (d, 2H, 4-
CF3C6H4N-), 7.24 (t, 3H, =C=CHPh-H), 7.08–7.23 (m, 10H,
PPh2-H), 7.01 (d, 2H, 4-CF3C6H4N-), 6.51 (d, 2H, =C=
Adv. Synth. Catal. 2011, 353, 411 – 425
ꢁ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
421

Hung Wai Cheung et al.
FULL PAPERS
CHPh-H), 6.34 (s, 2H, Tp-H), 5.49 (d, 1H, Tp-H), 5.36 (t,
1H, Tp-H), 4.50 (t, 1H, =C=CHPh); 31P{1H} NMR
(161.7 MHz, CDCl3, 258C): d=76.01 (s); 13C{1H} NMR
General Procedure for TpRu[4-CF3C6H4NACHTNURTGNEUNG(PPh2)2]
(OTf) (I)-Catalyzed Addition of b-Diketones to 1-
Alkynes
(100.61 MHz, CDCl3, 258C): d=375.74 (t, JP, C =18.1 Hz, =
+
The reactions were carried out in 11-mm Schlenk tubes
equipped with Teflon screw caps. (The reactions in Table 2,
entries 7–9, 11, 13 were carried out in 5-mm pressure-valved
NMR tubes under 10 bar of argon). In a typical run, rutheni-
um complex (0.005 mmol, 0.4 mol%) was loaded into the
tube; the system was evacuated and filled with nitrogen for
four cycles. b-Diketones (1.25 mmol) and terminal alkynes
(1.50 mmol) were then added to the tube via syringes and
needles. The tube was heated in a silicon oil bath at 1208C.
At the end of the specific period, the product was isolated
by flash column chromatography on silica gel or by prepara-
tive thin layer chromatography (silica gel). The organic
products 3b, 3c, 3d, 3e, 3f, 3g, 3h and 3k are new com-
ꢀ
C=CHPh); ESI-MS: m/z=945.30, [MÀPhC CH] .
ꢀ
TpRu[4-CF3C6H4N
(PPh2)2]
N
Freshly degassed ethanol (10 mL) was added to the complex
{TpRu[4-CF3C6H4N(PPh2)2](=C=CHPh)]OTf (0.5 g,
A
ACHTUNGTRENNUNG
0.45 mmol) and NaOH (0.09 g, 2.30 mol); the resulting mix-
ture was stirred at room temperature for 30 min. At the end
of this period, the solvent of the mixture was removed
under reduced pressure. The residue was extracted with tol-
uene (2ꢄ10 mL). The insoluble material was filtered out.
The solvent of the filtrate was removed under reduced pres-
sure and a yellow paste was obtained. Hexane (5 mL) was
added to the residue, with stirring, to produce a yellow
solid. The solid was filtered out and washed with hexane/
ethanol (3:2, 2ꢄ5 mL). It was then collected and dried
under vacuum at room temperature; yield: 0.23 g (55%);
anal. calcd. (%) for C48H39BF3N7P2Ru: C 61.03, H 4.16, N
1
pounds; they were characterized by H, 13C{1H} NMR spec-
troscopy, mass spectrometry and HR-MS analysis.
NMR Monitoring of TpRu[4-CF3C6H4NACHTNUTGRENUNG(PPh2)2]OTf
(I)-Catalyzed Addition of b-Diketones to 1-Alkynes
10.38; found: C 61.17, H 4.31, N 10.16; IR (KBr): n(B H) 2480
À
1
(br), n(C C) =2086 cmÀ1 (vs); H NMR (400.13 MHz, CDCl3,
The reactions were carried out in 11-mm Schlenk tubes
equipped with Teflon screw caps. Ruthenium complex
TpRu[4-CF3C6H4NACTHNUTRGENNGU(PPh2)2]HCATUNGTRNE(NUGN OTf) (0.005 mmol, 0.40 mol%)
ꢀ
258C): d=8.49–8.51 (m, 4H, PPh2-H), 7.78 (s, 2H, Tp-H),
7.60–7.62 (m, 4H, PPh2-H), 7.49 (s, 2H, Tp-H), 7.49 (s, 1H,
Tp-H), 7.44 (d, 2H, 4-CF3C6H4N-), 7.25 (m, 4H, PPh2-H),
was loaded into each of the eight tubes equipped with mag-
netic stirrers. The tubes were evacuated and filled with ni-
trogen for four cycles. Acetylacetone (1.25 mmol) and phe-
nylacetylene (1.50 mmol) were then added to each tube via
syringes and needles. The tubes were sealed with the screw
caps and heated in a silicon oil bath at 1208C. At different
time intervals, a tube was withdrawn from the silicon oil
ꢀ
ꢀ
7.17 (q, 3H, -C CPh-H), 7.08 (m, 2H, -C CPh-H), 7.07 (d,
2H, 4-CF3C6H4N-), 6.94 (m, 4H, PPh2-H), 6.88 (m, 4H,
PPh2-H), 5.92 (d, 2H, Tp-H), 5.41 (d, 1H, Tp-H), 5.40 (t,
1H, Tp-H); 31P{1H} NMR (161.7 MHz, CDCl3, 258C): d=
90.66 (s); 13C{1H} NMR (100.61 MHz, CDCl3, 258C): d=
121.56 (t, JP, C =30 Hz, -C CPh); ESI-MS: m/z=945.32 [M] .
+
ꢀ
1
bath and rapidly cooled down to room temperature; H, 19F
and 31P{1H} NMR spectra of the mixture were taken. The
relative concentrations of the species present were obtained
by comparing the integrations of their signals in the
31P{1H} NMR spectra. Conversion of the reaction was ob-
tained by measuring the integrations of the characteristic
peaks of the products with reference to distinct peaks of un-
reacted acetylacetone in the 1H NMR spectrum.
(PPh2)2](CO)}+OTfÀ (Id)
ACHTUNGTRENNUNG{TpRu[4-CF3C6H4NACHUTNGTRENNGUN
The reaction was carried out in a 250-mL stainless steel au-
toclave. The complex TpRu[4-CF3C6H4N(PPh2)2]OTf (0.5 g,
AHCTUNGTRENNUNG
0.5 mmol) was dissolved in freshly degassed chloroform
(10 mL). The solution was heated under 5 bar of CO at
1208C for 30 min. At the end of this period, the mixture was
cooled to room temperature and evaporated to dryness
under reduced pressure to yield a white paste. Hexane
(5 mL) was added to the residue, with stirring, to produce a
white solid. The solid was filtered out and washed with di-
ethyl ether (2ꢄ5 mL). It was collected and dried under
vacuum at room temperature; yield: 0.41 g (80%); anal.
calcd. (%) for C42H34BF6N7O4P2RuS: C 49.43, H 3.36, N
General Procedure for TpRu[4-CF3C6H4NACHTNURTGNEUNG(PPh2)2]
OTf (I)-Catalyzed Hydroamination of Terminal
Alkynes with Secondary Amines
The reactions were carried out in 11-mm Schlenk tubes
equipped with Teflon screw caps. In a typical run, ruthenium
9.61; found: C 50.15, H 3.49, N 9.44; IR (KBr): n(BÀH) =2525
complex
TpRu[4-CF3C6H4N
G
(0.01 mmol,
1
(br), u(C O) =1995 cmÀ1 (vs); H NMR (400.13 MHz, CDCl3,
ꢀ
1.00 mol%) was loaded into the tube. The tube was evacuat-
ed and filled with nitrogen for four cycles. Methanol
(0.10 mL), secondary amine (1.0 mmol) and terminal alkyne
(1.2 mmol) were then added to the tube via syringes and
needles. The tube was sealed with the screw cap and the so-
lution was stirred in a silicon oil bath at 1208C for 24 h. At
the end of this period, the tube was cooled to room temper-
ature and 25 mL of 1,1,2,2-tetrachloroethane were added as
internal standard; a 0.1 mL aliquot of the solution was re-
moved and analyzed by 1H NMR spectroscopy (in C6D6).
Conversion of the reaction was obtained by measuring the
integrations of the characteristic peaks of the products with
reference to distinct peaks of the internal standard. The or-
ganic products described in Table 3 are known compounds
258C): d=7.81 (s, 2H, Tp-H), 7.77–7.79 (m, 10H, PPh2-H),
7.50 (d, 1H, Tp-H), 7.46–7.50 (t, 2H, PPh2-H), 7.40 (d, 2H,
4-CF3C6H4N-), 7.24–7.28 (m, 4H, PPh2-H), 7.11–7.15 (m,
4H, PPh2-H), 7.13 (s, 2H, Tp-H), 6.94 (d, 2H, 4-CF3C6H4N-
), 6.31 (s, 2H, Tp-H), 5.43 (d, 1H, Tp-H), 5.35 (t, 1H, Tp-
H); 31P{1H} NMR (161.7 MHz, CDCl3, 258C): d=80.66 (s);
13C{1H} NMR (100.61 MHz, CDCl3, 258C): d=201.06 (t,
+
ꢀ
J
P, C =14.7 Hz, -C O); ESI-MS: m/z=872.24 [M] .
422
asc.wiley-vch.de
ꢁ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2011, 353, 411 – 425

Hydro(trispyrazolyl)borato-Ruthenium(II) Diphosphinoamino Complex-Catalyzed Addition of b-Diketones
Table 3. TpRu[4-CF3C6H4NACHTNUTRGENNUG(PPh2)2]ACHUTNTGRNE(NUGN OTf) (I)-catalyzed hydroamination of 1-alkynes with sec-
ondary amines.[a]
[a]
Reaction conditions: catalyst (0.01 mmol), secondary amine (1 mmol), terminal alkyne
(1.2 mmol); in 0.1 mL MeOH, 1208C, 24 h.
Conversion determined by H NMR spectroscopy with 1,1,2,2-tetrachloroethane as an in-
ternal standard.
48 h.
[b]
[c]
1
and were characterized by comparing their 1H NMR data
with the reported ones.
1.96 (s, 6H, methyl-CH3); 13C{1H} NMR (100 MHz, CDCl3):
d=191.52, 160.09, 143.26, 132.55, 127.51, 116.53, 114.42,
114.38, 55.51, 23.798; HR-MS (+ESI): m/z=233.1171, calcd.
for C14H16O3 [M+H]+: 232.1099.
4-Hydroxy-3-(1-p-tolylvinyl)pent-3-en-2-one (3c): Pale
yellow oil; 1H NMR (400 MHz, CDCl3): d=16.73 (s, 1H,
enol-OH), 7.38 (d, J=8 Hz, 2H, 4-CH3C6H4-), 7.18 (d, J=
8 Hz, 2H, 4-CH3C6H4-), 5.91 (s, 1H, -C=CH2), 5.21 (s, 1H,
-C=CH2), 2.38 (s, 3H, 4-CH3C6H4-), 2.02 (s, 6H, methyl-
CH3); 13C{1H} NMR (100 MHz, CDCl3): d=191.59, 143.78,
138.43, 137.26, 129.86, 126.29, 117.74, 114.37, 23.90, 21.48;
HR-MS (+ESI): m/z=217.1227, calcd. for C14H16O2 [M+
H]+: 216.2756.
NMR Monitoring of TpRu[4-CF3C6H4NACHTNUTGRENUNG(PPh2)2]OTf
(I)-Catalyzed Hydroamination of Phenylacetylene
with Diethylamine
The reaction was carried out in a 5-mm NMR pressure-
valved NMR tube. The ruthenium complex TpRu[4-
CF3C6H4NACHTUNGTRENNUNG(PPh2)2]OTf (0.01 mmol, 1.00 mol%) was loaded
to the tube; it was evacuated and filled with nitrogen for
four cycles. CD3OD (0.1 mL), diethylamine (1.0 mmol) and
phenylacetylene (1.2 mmol) were then added to the tube via
syringes and needles. The tube was heated in a silicon oil
bath at 1208C under 10 bar of argon. At different time inter-
vals, the NMR tube was rapidly cooled down to room tem-
perature and 1H and 31P{1H} NMR spectra of the solution
were taken. The relative concentrations of the species pres-
ent were obtained by comparing the integrations of their
signals in the 31P{1H} NMR spectra. Conversion of the reac-
tion was obtained by measuring the integrations of the char-
acteristic peaks of the products with reference to distinct
3-[1-(4-Bromophenyl)vinyl]-4-hydroxypent-3-en-2-one
1
(3d): Pale yellow oil; H NMR (400 MHz, CDCl3): d=16.84
(s, 1H, enol-OH), 7.56 (d, J=8 Hz, 2H, 4-BrC6H4-), 7.44 (d,
J=8 Hz, 2H, 4-BrC6H4-), 6.04 (s, 1H, -C=CH2), 5.39 (s, 1H,
-C=CH2), 2.08 (s, 6H, methyl-CH3); 13C{1H} NMR
(100 MHz, CDCl3): d=191.71, 143.14, 139.31, 132.47, 128.18,
122.85, 119.68, 113.90, 24.12; HR-MS (+ESI): m/z=
281.0188, calcd. for C13H13BrO2 [M]+: 281.1451.
3-[1-(4-Fluorophenyl)vinyl]-4-hydroxypent-3-en-2-one
1
1
(3e): Pale yellow oil; H NMR (400 MHz, CDCl3): d=16.66
peaks of unreacted diethylamine in the H NMR spectrum.
(s, 1H, enol-OH), 7.38 (dd, J=6, 8 Hz, 2H, 4-FC6H4-), 6.97
3-(1-Hydroxyethylidene)-4-(4-methoxyphenyl)pent-4-en-
2-one (3b): Pale yellow oil; H NMR (400 MHz, CDCl3): d=
16.66 (s, 1H, enol-OH), 7.35 (d, J=9 Hz, 2H, 4-OCH3C6H4-
1
(t, J=8 Hz, 2H, 4-FC6H4-), 5.81 (s, 1H, -C=CH2), 5.18 (s,
ACTHNGUTERNNUG
1H, -C=CH2), 1.93 (s, 6H, methyl-CH3); 13C{1H NMR
), 6.85 (d, J=9 Hz, 2H, 4-OCH3C6H4-), 5.78 (s, 1H, -C= (100 MHz, CDCl3): d=191.62, 164.38, 161.92, 142.99, 136.36,
CH2), 5.10 (s, 1H, -C=CH2), 3.77 (s, 3H, 4-OCH3C6H4-), 128.09, 118.55, 116.12, 115.91, 114.13, 23.84; HR-MS (+
Adv. Synth. Catal. 2011, 353, 411 – 425
ꢁ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
423

Hung Wai Cheung et al.
FULL PAPERS
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4-Hydroxy-3-(1-(thiophen-3-yl)vinyl)pent-3-en-2-one (3f):
Pale yellow oil; 1H NMR (400 MHz, CDCl3): d=16.59 (s,
1H, enol-OH), 7.08 (m, 1H, thiophene-H), 7.25–7.29 (m,
1H, thiophene-H), 7.29–7.33 (m, 1H, thiophene-H), 5.81 (s,
1H, -C=CH2), 5.15 (s, 1H, -C=CH2), 2.00 (s, 6H, methyl-
CH3); 13C{1H} NMR (100 MHz, CDCl3): d=191.57, 142.85,
139.00, 127.12, 125.52, 122.97, 117.52, 114.51; HR-MS (+
ESI): m/z=209.0639, calcd. for C11H12O2S [M+H]+:
208.2768.
3-(1-Cyclopentylideneethyl)-4-hydroxypent-3-en-2-one
1
(3g): Pale yellow oil; H NMR (400 MHz, CDCl3): d=16.12
(s, 1H, enol-OH), 2.11 (m, 2H, cyclopentyl-CH2), 1.82 (m,
2H, cyclopentyl-CH2), 1.79 (s, 6H, methyl-CH3), 1.59 (s,
6H, methyl-CH3), 1.53 (m, 2H, cyclopentyl-CH2), 1.44 (m,
2H, cyclopentyl-CH2); 13C{1H} NMR (100 MHz, CDCl3): d=
190.29, 144.85, 121.53, 116.12, 32.41, 30.97, 27.21, 22.98,
21.18; HR-MS (+ESI): m/z=195.1384, calcd. for C12H18O2
[M+H]+: 194.2701.
3-(1-Hydroxyethylidene)-4,7-dimethyloct-4-en-2-one (3h):
Pale yellow oil; 1H NMR (400 MHz, CDCl3): d=16.46 (s,
1H, enol-OH), 5.54 (t, J=7 Hz,1H, =CHCH2-), 1.99 (s, 6H,
methyl-CH3), 1.83 (s, 3H, methyl-CH3), 1.74 (t, J=7 Hz,
2H, =CHCH2-), 1.61 [m, 1H, -CHACHTUNGTREN(NUGN CH3)2], d 0.86 [d, J=
6 Hz, 6H, -CH
ACHTUNGTRENNUNG
d=190.77, 132.28, 131.98, 113.46, 39.14, 29.00, 25.82, 23.49,
23.27; HR-MS (+ESI): m/z=197.1543, calcd. for C12H20O2
[M+H]+: 196.286.
4-Hydroxy-6-methyl-3-(1-phenylvinyl)heptan-2-one (3k):
Pale yellow oil; 1H NMR (400 MHz, CDCl3): d=17.17 (s,
1H, enol-OH), 7.66 (d, J=7 Hz, 2H, Ph-H), 7.54 (t, J=
7 Hz, 2H, Ph-H), 7.49 (m, 1H, Ph-H), 6.14 (s, 1H, -C=CH2),
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[m, 2H, -CH2CH(CH3)2], 2.20 (s, 3H, methyl-CH3), 1.03–
1.71 [m, 6H, -CH2CH
(CH3)2]; 13C{1H} NMR (100 MHz,
CDCl3): d=193.00, 192.68, 143.72, 140.28, 129.09, 128.55,
126.27, 118.89, 114.48, 44.79, 26.17, 24.31, 22.93; HR-MS
(+ESI): m/z=245.1540, calcd. for C16H20O2 [M+H]+:
244.3288.
ACHTUGNTRNEN(UNG CH3)2], 2.33
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
Acknowledgements
We acknowledge financial support from the Research Grant
Council of Hong Kong (Project Nos. PolyU 5006/07P, PolyU
5011/08P).
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