Palladium and platinum catalyzed hydroselenation of alkynes: Se-H vs Se-Se addition to C≡C bond

Article abstract of DOI:10.1016/S0022-328X(03)00546-1

A mechanistic study of the hydroselenation of alkynes catalyzed by Pd(PPh₃)₄ and Pt(PPh₃)₄ has shown that the palladium complex gives products of both Se-H and Se-Se bond addition to the triple bond of alkynes, while the platinum complex selectively catalyzes Se-H bond addition. The key intermediate of PhSeH addition to the metal center, namely Pt(H)(SePh)(PPh₃)₂, was detected by ¹H-NMR spectroscopy. The analogous palladium complex rapidly decomposes with evolution of molecular hydrogen. A convenient method was developed for the preparation of Markovnikov hydroselenation products H₂C=C(SePh)R, and the scope of this reaction was investigated. The first X-ray structure of the Markovnikov product H₂C=C(SePh)CH₂N⁺ HMe₂·HOOC=COO^- is reported.

Full text of DOI:10.1016/S0022-328X(03)00546-1

Journal of Organometallic Chemistry 679 (2003) 162Á172
/
www.elsevier.com/locate/jorganchem
Palladium and platinum catalyzed hydroselenation of alkynes:
SeꢀH vs SeꢀSe addition to CꢁC bond
/
/
/
Valentine P. Ananikov a,*, Denis A. Malyshev a, Irina P. Beletskaya b,*,1,
Grigory G. Aleksandrov c, Igor L. Eremenko c
a Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect 47, Moscow 119991, Russia
b Department of Chemistry, Lomonosov Moscow State University, Vorob’evy gory, Moscow 119899, Russia
c Kurnakov Institute of General and Inorganic Chemistry, Leninsky Prospect 31, Moscow 117907, Russia
Received 12 March 2003; received in revised form 8 June 2003; accepted 9 June 2003
Abstract
A mechanistic study of the hydroselenation of alkynes catalyzed by Pd(PPh3)4 and Pt(PPh3)4 has shown that the palladium
complex gives products of both SeꢀH and SeꢀSe bond addition to the triple bond of alkynes, while the platinum complex selectively
catalyzes SeꢀH bond addition. The key intermediate of PhSeH addition to the metal center, namely Pt(H)(SePh)(PPh3)2, was
/
/
/
1
detected by H-NMR spectroscopy. The analogous palladium complex rapidly decomposes with evolution of molecular hydrogen.
A convenient method was developed for the preparation of Markovnikov hydroselenation products H2CꢂC(SePh)R, and the scope
C(SePh)CH2NꢀHMe2×
HOOCꢀ
/
of this reaction was investigated. The first X-ray structure of the Markovnikov product H2Cꢂ
/
/
/
COOꢁ is reported.
# 2003 Elsevier B.V. All rights reserved.
Keywords: Hydroselenation; Vinyl selenide; Platinum complex; Palladium complex; Catalytic reaction; 77Se-NMR
1. Introduction
bonds to alkynes is significantly less studied. In many
addition reactions of this type either palladium or
platinum complexes are involved. The yields and
selectivity of the catalytic processes are dependent on
metal and very often are rather difficult to rationalyze
The transition-metal-catalyzed addition of Eꢀ
EꢀH bonds to alkynes is an important method of
organic synthesis [1Á4]. It successfully serves as an
/E and
/
/
initial step in the catalytic heterofunctionalization of
organic compounds, highly valuable for the develop-
ment of various carbon-element frameworks [1]. Vinyl
selenides are in demand in both the synthetic organic
[1Á
/
17].
Our recent study on the addition of PhSeSePh to Cꢁ
/C
bond has shown that the similar Pd(PPh3)4 and
Pt(PPh3)4 complexes lead to different intermediates in
the catalytic cycle [15]. Palladium catalyzed transforma-
tion involves dinuclear complexes (2, 3). In contrast,
platinum complexes (5, 6) are mononuclear, and only
the unstable cis-isomer (5) exhibits the desired activity
[15] as shown in Scheme 1 (PPh3 ligand dissociation/
association is omitted in the schemes for simplicity
reasons). Under reaction conditions platinum complexes
quickly lose the catalytic activity due to the isomeriza-
chemistry [5Á8] and material science [9,10].
/
However, the mechanism of these catalytic reactions
is not fully understood and deserves further detailed
studies. Much attention has been paid to develop
appropriate methodology of Sꢀ
[1,4,14] addition reactions to alkynes. However, the
addition of SeꢀSe [14,15] and, especially, SeꢀH [16,17]
/
H [3,11Á
/
13] and Sꢀ
/S
/
/
* Corresponding author. Tel.: ꢀ
5328.
E-mail
beletska@org.chem.msu.ru (I.P. Beletskaya).
/
7-95-135-5328; fax: ꢀ
/
7-95-135-
tion 50
dium and mononuclear complexes of platinum were also
observed in stoichiometric EꢀE addition and ligand
substitution reactions [18Á25].
/
6. Dinuclear chalchogenide complexes of palla-
addresses:
val@ioc.ac.ru
(V.P.
Ananikov),
/
1
/
Fax: ꢀ7-95-939-3618.
/
0022-328X/03/$ - see front matter # 2003 Elsevier B.V. All rights reserved.
doi:10.1016/S0022-328X(03)00546-1

V.P. Ananikov et al. / Journal of Organometallic Chemistry 679 (2003) 162Á
/172
163
Scheme 1.
Therefore, we decided to investigate platinum and
palladium catalyzed addition of PhSeH to alkynes, and
to compare the catalytic activity of Pt vs Pd complexes
are formed in a non-catalytic addition (Table 1). For
activated alkynes the side reaction leading to 10 and 11
is fast compared to catalytic transformation and we
were unable to obtain Markovnikov products in a good
and the mechanism of Seꢀ
/
H vs Seꢀ/Se bond addition.
In the present article we report the mechanistic study
of transition metal catalyzed PhSeH addition to alkynes.
Both Pd- and Pt-catalyzed reactions are described.
yield (Table 1, No. 5, 6). In the other cases (7AÁ7D) in
/
palladium catalyzed reaction both the Markovnikov
product 8 and bis-selenide 9 were detected. The struc-
tures of the products were determined using 2D 1H-77Se
HMQC, NOESY and LR-COSY NMR experiments.
The use of platinum catalyst with the same set of alkynes
2. Results and discussion
(7AÁ
/
7D) leads to the formation of 8 and Ph2Se2 (Table
1).
Palladium catalyzed addition of PhSH and PhSeH to
terminal alkynes is known to occur according to the
The most interesting feature of the studied system is
the presence of both mono- and bis-seleno substituted
products (8 and 9, respectively) in comparable yields for
palladium catalyzed transformation while with platinum
catalyst the reaction is highly selective and yields only 8
Markovnikov rule [11Á17]. In some cases anti-Markov-
/
nikov by-products of cis- or trans- geometry may be
formed as a result of non-catalytic side-reactions. In our
study PhSeH addition leads to Markovnikov product
(Table 1, No. 1Á
To clarify the reaction mechanism we have under-
taken 31P- and 1H-NMR study of the Pd(PPh3)4Á
PhSeH
/
4).
(8), except for activated alkynes with RꢂPh, COOMe
(Scheme 2). Performing the reaction without catalyst
clearly showed that anti-Markovnikov products (10, 11)
/
/
Scheme 2.

164
V.P. Ananikov et al. / Journal of Organometallic Chemistry 679 (2003) 162Á
/172
Table 1
The yields a (in %) of PhSeH addition reaction to alkynes under various conditions
No Alkyne
Pd(PPh3)4 catalyzed 8:9:10:11
Pt(PPh3)4 catalyzed b 8:9:10:11
Non-catalyzed 8:9:10:11
1
2
3
4
5
6
7A
7B
7C
7D
7E
7F
20:36:0:0
49:25:0:0
42:42:0:0
40:40:0:0
19:0:19:62
0:15 c:18:67
60:0:0:0
60:0:0:0
0:0:0:0
0:0:0:0
0:0:0:0
0:0:0:0
0:0:17:63
0:0:7:73
55:0:0:0
51:0:0:0
21:0:13:62
0:3 c:10:70
Heated at 80 8C for 13 h in toluene solutions, see Section 4 for details.
Determined by NMR spectroscopy and calculated according to PhSeH conversion.
a
b
Ph2Se2 is also obtained in 20Á
/
25% yield.
Mixture of E/Z isomers see Ref. [15] for details.
c
system in benzene-d6 at room temperature. 31P{1H}-
NMR spectrum showed dꢂ28.2 and 26.8 ppm peaks
additional check has been performed with the authentic
sample of H2 dissolved in benzene-d6 (Fig. 1C).
/
We suggest that PhSeH undergoes oxidative addition
to Pd0 and molecular hydrogen is formed as a result of
Pd(H)(SePh)(PPh3)2 decomposition (Pathway A,
Scheme 3). The other possible pathway of hydrogen
formation may involve a direct reaction of the above
complex with PhSeH (Pathway B) or oxidative addition
of the second phenylselenol molecule and reductive
elimination from the PdIV complex (Pathway C). It
was shown earlier that mononuclear palladium disele-
nides are subject of fast dimerization to form dinuclear
[19,21,22]. In agreement with this observation
Pd(PPh3)2(SePh)2 gives dinuclear complexes 2 and 3,
both detected with 31P-NMR spectroscopy.
with the relative ratio of about 3:1, which correspond to
trans- and cis-isomers of dinuclear complex (2, 3) [15].
The other signals in the spectrum were: 25.0 ppm
(OPPh3), 22.3 ppm and ꢁ4.6 ppm (PPh3). Thus, in
/
reaction of PhSeH with Pd(PPh3)4 the same intermedi-
ate complexes are formed as in the oxidative addition of
PhSeSePh to Pd(PPh3)4. Since we have shown that
dinuclear complexes (2, 3) catalyze the addition of
diphenyl diselenide to alkynes [15], this observation
explains why product 9 is formed under the catalytic
conditions.
Upon the addition of palladium complex colorless
PhSeH solution rapidly darkened and gas evolution was
1
The catalytic Eꢀ
proceed via the following sequence: (i) oxidative addi-
tion of Eꢀ
H to Pd0 giving 12, (ii) alkyne insertion
leading to s-vinyl derivative 13 and (iii) releasing the
final product 8 after the CꢀH reductive elimination
stage (Scheme 4). It should be noted that alkyne
insertion occurs only into the PdꢀSe bond, otherwise
/H bond addition to alkynes can
observed. In H-NMR spectrum the signal at dꢂ
/
4.5
ppm corresponding to H2 dissolved in benzene was
/
detected (Fig. 1A, literature data [26]: d :4.5 ppm in
/
toluene-d8). The hydrogen signal disappears after pur-
ging the solution with argon in NMR tube (Fig. 1B). An
/
/
anti-Markovnikov products should be observed. Under
catalytic conditions intermediate 12 can give the di-
nuclear complexes (2, 3). The dinuclear complexes are
known to catalyze PhSeSePh addition to alkynes [15],
through the alkyne insertion (14) and Cꢀ
/
Se reductive
elimination giving 9. Reductive elimination releases Pd0
complex, and the process is most likely accompanied by
the dissociation of dinuclear derivative 14. Another
mechanism of Markovnikov product (8) formation
involves trapping of the intermediate 14 with acid
(PhSeH). Trapping with PhSeH does not change palla-
dium oxidation state and the corresponding dinuclear
derivatives (2, 3) are formed from 14.
In fact, three catalytic processes may take place in the
studied system: one pathway to accomplish a formal
PhSeSePh addition to the triple bond leading to 9, and
two other pathways to achieve PhSeH addition giving 8.
To clarify the Markovnikov product formation me-
chanism we have performed additional experiments. A
Fig. 1. (A) 1H-NMR spectrum of hydrogen in reaction mixture
(benzene-d6); (B) 1H-NMR spectrum of the reaction mixture after
purging with argon; (C) 1H-NMR spectrum of authentic hydrogen
sample (benzene-d6).

V.P. Ananikov et al. / Journal of Organometallic Chemistry 679 (2003) 162Á
/172
165
Scheme 3.
mixture of complexes 2 and 3 has been prepared in
benzene-d6 by the oxidative addition reaction of Ph2Se2
to Pd0 (15 min, 80 8C). Alkyne (HCꢁ
CCH2CH2OH)
and acid (CF3COOH) were added and the mixture was
product 8 (Table 1). Comparing Pd(PPh3)4 and
Pt(PPh3)4 one may clearly see that the latter is superior
to provide better selectivity of the process and higher
yield. In our experience the mixture of 8 and 9 is rather
difficult to separate. Therefore, the less selective palla-
dium catalyzed reaction should be considered as inferior
from practical point of view. Since no by-products are
formed in the platinum catalyzed transformation (except
Ph2Se2), the isolation procedure can be significantly
simplified. In addition, platinum catalyzed reaction is
not sensitive to Ph2Se2 impurities in PhSeH, which may
be present due to easy oxidation of the latter by air.
The key intermediate of PhSeH oxidative addition
/
heated at 80 8C for 3 h. H- and H-77Se HMQC NMR
analysis of the products has detected a mixture of 8 and
9 in 31 and 15% yields, respectively, calculated based on
initial Pd0. If the same reaction is performed in the
absence of acid only 9 is obtained in 50% yield.
Therefore, the experiments confirm that 8 can be
obtained upon trapping complex 14 with acid. Since
hydride complex 12 was not detected and complexes 2, 3
are immediately formed, trapping 14 with PhSeH could
be the dominating pathway of hydroselenation of
alkynes catalyzed by palladium complexes. This finding
is in agreement with earlier study [16], suggesting that
phenylselenol addition to alkynes involves the formation
of palladium complex with s-vinyl ligand (14) followed
by reaction with PhSeH. However, our results show that
the Markovnikov product 8 is not the only one [16].
Besides trapping with PhSeH, the intermediate complex
14 can undergo reductive elimination leading to bis-
seleno substituted compound 9.
1
1
1
reaction to Pt0 has been detected by H-NMR spectro-
scopy (15, Scheme 5). The singlet at dꢂ
with platinum and selenium satellites (JPtꢀH
JSeꢀH 44.1 Hz) clearly confirms the presence of
/
ꢁ
/
8.77 ppm
ꢂ/999.8 Hz,
ꢂ
/
hydride proton bonded to the metal (Fig. 2). Since
2
2JPꢀH coupling is not observed, while JSeꢀH coupling is
present, most likely there is no phosphine ligand in
trans- position to hydrogen and we can conclude that 15
is trans-[Pt(H)(SePh)(PPh3)2]. This finding agrees with
earlier studies of oxidative addition of thiols and
selenols to low-valent transition metal complexes
[27,28].
31P{1H}-NMR monitoring of the PhSeH reaction
with Pt(PPh3)4 in benzene-d6 at room temperature has
shown the major resonances: 20.8 ppm with 195Pt
Recently, we have shown that Pt(PPh3)4 does not
catalyze the addition of PhSeSePh to alkynes contrary
to palladium [15]. Surprisingly, Pt(PPh3)4 was found to
serve as efficient catalyst in PhSeH addition reaction,
which results in the formation of a single Markovnikov
Scheme 4.

166
V.P. Ananikov et al. / Journal of Organometallic Chemistry 679 (2003) 162Á172
/
Scheme 5.
in 31P{1H}-NMR spectra of the catalytic reaction
mixture after heating at 80 8C only the signals corre-
sponding to the trans-isomer were detected. Most likely
there is a competition of PhSeSePh and PhSeH oxidative
addition to zero valent metal. The product is formed by
trapping of 15 with alkyne. During the catalytic reaction
Ph2Se2 accumulates due to the decomposition of hydride
complex, and this process may lower the overall yield of
8. The presence of Ph2Se2 in the reaction mixture was
unambiguously confirmed by 1H-77Se HMQC experi-
ment. The final yield of diphenyl diselenide is 20Á25%
/
based on initial PhSeH (Table 1). For preparative
purposes PhSeSePh can be easily separated and recycled
to PhSeH (for the PhSeH synthesis from Ph2Se2 see
[8,29]).
To confirm the reaction mechanism trans-
[Pt(SePh)2(PPh3)2] (6) was prepared and used as a
catalyst in PhSeH addition to 7B. The same 60% yield
of 8B was obtained as in the Pt(PPh3)4 catalyzed
reaction (Table 1).
To clarify the mechanism of Markovnikov product
formation an additional experiment has been per-
formed, similar to palladium system discussed above.
After Ph2Se2 reaction with Pt0 (15 min, 80 8C in
Fig. 2. 1H-NMR spectrum of hydride proton region of 15 (toluene-d8).
satellites JPtꢀP
JPtꢀP 2966 Hz, which correspond to trans-
[Pt(SePh)2(PPh3)2] (6) and cis-[Pt(SePh)2(PPh3)2] (5),
respectively, [15] 25.0 ppm (OPPh3) and ꢁ4.6 ppm
ꢂ
/
2842 Hz, 18.5 ppm with 195Pt satellites
ꢂ
/
benzene-d6) the addition of alkyne (HCꢁ
and acid (CF3COOH) gave no product. Only the traces
of 8 (yield Â
0.5% based on initial Pt0) were detected
/CCH2CH2OH)
/
(PPh3). The other minor resonances in the spectrum are:
20.8, 23.7, 30.6 ppm. One of the minor resonances may
correspond to the hydride complex 15. It should be
noted that analogous palladium complex (12) was not
detected under the similar conditions. The most likely
reason is a higher reactivity of 12 compared to 15. At
room temperature 5 slowly isomerizes to 6.
For platinum complexes we can suggest an analogous
mechanism as for the palladium complexes discussed
above. Reaction of Pt0 with two molecules of PhSeH
leads to the same metal complexes (5, 6) as reaction of
Pt0 with PhSeSePh (Scheme 5). However, at 80 8C cis-
[Pt(SePh)2(PPh3)2] (5) very rapidly isomerizes to trans-
[Pt(SePh)2(PPh3)2] (6) (Scheme 1) [15], thus avoiding bis-
selenide 9 formation under catalytic conditions. Indeed,
/
after 3 h at 80 8C. These observation rules out the
pathways involving trapping of platinum s-vinyl inter-
mediate with acid, in contrast to the palladium catalyzed
reaction.
The X-ray quality single crystals were obtained for the
oxalic acid salt of 8C. The molecular structure of the
compound is shown in Fig. 3, main geometry para-
meters are summarized in Table 2. Two slightly different
conformations were found in the crystal (see torsion
angles in Table 2). The molecule possess typical
geometry expected for Markovnikov product with the
vinyl group Cꢂ
/
C bond lengths of 1.322(8) and 1.330(8)
Se bond lengths are of 1.917(6) and 1.918(6)
˚
A. The hydrogen bonds involving carboxylic oxygen
˚
A. The Cꢀ
/

V.P. Ananikov et al. / Journal of Organometallic Chemistry 679 (2003) 162Á
/172
167
Fig. 3. Molecular structure and crystal packing for H2Cꢂ
/
C(SePh)CH2NꢀHMe2×
/
HOOCꢀ
/
COOꢁ (8C×
/
HOOCꢀCOOH).
/
atoms were found in the studied molecule, N(2)ꢀ
/
H(2)
/
Á Á Á
2.155 A (N(1)ꢀ
H(1) O(1)ꢂ2.137
Á Á Á
A). To the best of our knowledge this is the first X-ray
structure of organic molecule with H2CꢂCꢀSeꢀ frag-
ment. A very interesting feature of 8C is the presence of
noncovalent Se O interaction in the crystal, Se(2)ꢀ
Á Á Á
/
are responsible for modulation of biological activity of
selenium compounds [30].
A very interesting rearrangement of the terminal
vinylselenide 8B has been observed in chloroform
solution (Scheme 6). The 50% conversion of 8B was
˚
˚
O(5)ꢂ
/
2.098 A and N(2)ꢀ
/
H(2)
/
Á Á Á
/
O(7)ꢂ
/
/
˚
H(1)
˚
/
Á Á Á
/
O(3)ꢂ
/
2.134 A and N(1)ꢀ
/
/
/
/
/
/
/
achieved after Â
/
24 h and the reaction was almost
complete after a week with the final ratio 16B:17B:
/
/
/
/
˚
˚
1.4:1.0. Heterosubstituted vinyl selenides containing a-
hydrogen atoms (8A, 8C) under similar conditions do
O(5)ꢂ
/
3.741 A and Se(2)ꢀ
/
O(7)ꢂ
/
3.385 A. It was
suggested recently that noncovalent Se
/
Á Á ÁO interactions
/

168
V.P. Ananikov et al. / Journal of Organometallic Chemistry 679 (2003) 162Á172
/
Table 2
˚
Selected geometry parameters for 8C: bond lengths (in A), bond angles and torsion angles (8)
Parameter
Value
Parameter
Value
Parameter
Value
Bond lengths
Bond angles
Torsion angles
Se(1)ꢀ
Se(1)ꢀ
Se(2)ꢀ
Se(2)ꢀ
O(1)ꢀ
O(2)ꢀ
O(3)ꢀ
O(4)ꢀ
O(5)ꢀ
O(6)ꢀ
O(7)ꢀ
O(8)ꢀ
N(1)ꢀ
N(1)ꢀ
N(1)ꢀ
N(2)ꢀ
N(2)ꢀ
N(2)ꢀ
C(1)ꢀ
C(2)ꢀ
C(6)ꢀ
C(6)ꢀ
C(7)ꢀ
C(8)ꢀ
C(9)ꢀ
C(10)ꢀ
C(12)ꢀ
C(13)ꢀ
C(17)ꢀ
C(17)ꢀ
C(18)ꢀ
C(19)ꢀ
C(20)ꢀ
C(21)ꢀ
C(23)ꢀ
C(25)ꢀ
/
C(2)
1.918(6)
1.921(6)
1.917(6)
1.918(7)
1.193(7)
1.321(7)
1.277(7)
1.203(7)
1.199(7)
1.313(7)
1.265(6)
1.250(7)
1.490(7)
1.498(8)
1.500(7)
1.486(9)
1.492(7)
1.509(8)
1.322(8)
1.501(9)
1.350(9)
1.383(9)
1.393(9)
1.351(10)
1.373(11)
1.386(10)
1.330(8)
1.479(9)
1.373(8)
1.401(9)
1.359(10)
1.375(12)
1.366(11)
1.372(9)
1.541(8)
1.541(8)
C(2)ꢀ
C(13)ꢀ
C(3)ꢀN(1)ꢀ
C(3)ꢀN(1)ꢀ
C(4)ꢀN(1)ꢀ
C(15)ꢀ
C(15)ꢀ
C(16)ꢀ
C(1)ꢀC(2)ꢀ
C(1)ꢀC(2)ꢀ
C(3)ꢀC(2)ꢀ
N(1)ꢀC(3)ꢀ
C(11)ꢀC(6)ꢀ
C(11)ꢀC(6)ꢀ
C(7)ꢀC(6)ꢀ
C(6)ꢀC(7)ꢀ
C(9)ꢀC(8)ꢀ
C(8)ꢀC(9)ꢀ
C(9)ꢀ
C(6)ꢀ
C(12)ꢀ
C(12)ꢀ
C(14)ꢀ
C(13)ꢀ
C(22)ꢀ
C(22)ꢀ
C(18)ꢀ
C(19)ꢀ
C(18)ꢀ
C(21)ꢀ
C(20)ꢀ
C(21)ꢀ
O(1)ꢀC(23)ꢀ
O(1)ꢀC(23)ꢀ
O(2)ꢀC(23)ꢀ
O(4)ꢀC(24)ꢀ
O(4)ꢀC(24)ꢀ
O(3)ꢀC(24)ꢀ
O(5)ꢀC(25)ꢀ
O(5)ꢀC(25)ꢀ
O(6)ꢀC(25)ꢀ
O(8)ꢀC(26)ꢀ
O(8)ꢀC(26)ꢀ
O(7)ꢀC(26)ꢀ
/
Se(1)ꢀ
Se(2)ꢀ
/
C(6)
99.9(2)
100.4(3)
110.4(5)
111.9(5)
111.6(5)
111.0(5)
109.1(5)
111.1(5)
121.4(6)
125.7(5)
112.9(4)
113.7(5)
120.2(6)
121.5(5)
118.3(5)
118.7(6)
121.3(7)
119.1(7)
120.4(6)
120.3(7)
120.8(6)
124.3(5)
114.9(4)
113.6(5)
118.8(7)
120.0(5)
121.1(5)
119.5(7)
120.7(7)
120.4(8)
119.3(7)
121.2(7)
124.8(6)
122.0(6)
113.2(5)
127.6(5)
119.7(6)
112.7(5)
124.4(6)
122.0(6)
113.6(5)
126.1(6)
119.5(5)
114.4(5)
C(1)ꢀ
C(2)ꢀ
C(2)ꢀ
C(1)ꢀ
C(3)ꢀ
C(12)ꢀ
C(14)ꢀ
C(12)ꢀ
C(13)ꢀ
C(13)ꢀ
/
C(2)ꢀ
C(3)ꢀ
C(3)ꢀ
C(2)ꢀ
C(2)ꢀ
C(13)ꢀ
C(13)ꢀ
C(13)ꢀ
C(14)ꢀ
C(14)ꢀ
/
C(3)ꢀ
N(1)ꢀ
N(1)ꢀ
Se(1)ꢀ
Se(1)ꢀ
/
N(1)
113.22(0.67)
179.45(0.50)
54.49(0.62)
3.50(0.64)
/C(6)
/
/C(17)
/
/
/
C(4)
ꢁ
ꢁ
ꢁ
/
/C(13)
/
/
C(4)
C(5)
C(5)
/
/
/
C(5)
/
/C(17)
/
/
/
/
/
C(6)
C(6)
/
/
C(23)
C(23)
C(24)
C(24)
C(25)
C(25)
C(26)
C(26)
/
/
/
/
/
176.92(0.43)
0.91(0.64)
/
/
N(2)ꢀ
N(2)ꢀ
N(2)ꢀ
/C(16)
/
/
Se(2)ꢀ
Se(2)ꢀ
C(14)ꢀ
/
C(17)
C(17)
N(2)
/
/
/C(14)
/
/
/
ꢁ
/
176.72(0.47)
111.48(0.69)
176.29(0.55)
/
/
/C(14)
/
/
/
/
/
/
C(3)
Se(1)
Se(1)
/
/
N(2)ꢀ
/
C(15)
ꢁ/
/
/
/
/
/
N(2)ꢀ
/
C(16)
ꢁ/53.59(0.66)
/
/
/
/
/
/C(2)
/
C(3)
C(4)
/
/C(7)
/
/
/Se(1)
/
C(5)
/
/Se(1)
/
C(15)
C(16)
C(14)
C(2)
/
/C(8)
/
/
/C(7)
/
/
/C(10)
/
/
C(10)ꢀ
/C(11)
/
C(3)
/
C(11)ꢀ
/C(10)
/
C(11)
/
C(13)ꢀ
C(13)ꢀ
C(13)ꢀ
C(14)ꢀ
C(17)ꢀ
C(17)ꢀ
C(17)ꢀ
C(18)ꢀ
C(19)ꢀ
C(20)ꢀ
C(21)ꢀ
C(22)ꢀ
/
C(14)
Se(2)
Se(2)
N(2)
/
C(7)
/
/
/
C(8)
/
/
/
C(9)
/
/
/
C(10)
/
/
C(18)
Se(2)
Se(2)
C(17)
C(20)
C(19)
C(22)
C(17)
/
C(11)
C(13)
C(14)
C(22)
C(18)
C(19)
C(20)
C(21)
C(22)
C(24)
C(26)
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
O(2)
/
/
/
C(24)
C(24)
O(3)
/
/
/
/
/
/
/
/
C(23)
C(23)
O(6)
/
/
/
/
/
/
C(26)
C(26)
O(7)
/
/
/
/
/
/
C(25)
C(25)
/
/
that for the isomerization of vinyl selenide 8B transition
metal complexes are not required. This side reaction
may lower the overall selectivity of the PhSeH addition
to hexyne-1 (7B) leading to the mixture of isomers.
The theoretical calculations at the B3LYP/Lanl2dz
level were performed to predict relative stability of the
isomers. On the DH energy surface both 16B and 17B
are more stable compared to 8B by 3.0 and 2.4 kcal
molꢁ1, respectively. Therefore, the isomerization is
thermodynamically driven, while 8B is the kinetic
product.
Scheme 6.
not undergo the isomerization. In the case of PhSH
addition to alkynes double bond migration has been
observed under palladium catalyzed conditions [13],
again only for the acetylenic hydrocarbons without
heteroatomic substituents. The present study shows

V.P. Ananikov et al. / Journal of Organometallic Chemistry 679 (2003) 162Á
/172
169
1
3. Conclusions
4.2.1. 2D H-77Se HMQC NMR experiment
The spectrum was collected with 1H and 77Se 908
pulses of 12.5 and 16.0 ms, respectively, a relaxation
delay of 2s, Dꢂ
long range coupling constant of 2 Hz), a 0.25 s
acquisition time and 4500 and 25 000 Hz spectral
windows for the 1H(F2) and 77Se(F1) dimensions
correspondingly. Four or eight transients were averaged
for each of 256 increments on t1. The data was zero filled
We have shown that Pd(PPh3)4 catalyzed PhSeH
addition to alkynes leads to the mixture of mono- and
bis-seleno substituted products 8 and 9, whereas
Pt(PPh3)4 provides better selectivity and yield resulting
in Markovnikov product only (8). In both cases
palladium and platinum diselenide derivatives (2, 3
and 5, 6) can be formed from M0 and PhSeH. However,
/
(2×
/
JHꢀSe
)
ꢁ1ꢂ
250 ms (optimized for
/
Seꢀ
presence of platinum complex and PhSeSePh is released
instead. In contrast, palladium complexes catalyze Seꢀ
Se addition to the CꢁC bond leading to the mixture of
products. The CꢀH bond formation in palladium
/
Se addition to alkynes does not take place in the
to
2048ꢃ
/
2048
matrix
and
processed
with
2) window function for both F2 and F1
QSINE(SSBꢂ
/
/
dimensions. The 1 ms sine shaped pulse field gradient
pulses with the ratio 50.0:30.0:35.3 (%) followed with
100 ms recovery delay were applied.
/
/
catalyzed transformation most likely is an intermolecu-
lar trapping of s-vinyl intermediate 14 with PhSeH, in
contrast to intramolecular reductive elimination occur-
ring when platinum catalyst is used.
4.2.2. 2D NOESY NMR experiment
The spectra were recorded using bipolar gradient
pulse sequence: 90-t1-90-tmix/2Á
/
G1Á
/
180Á
/
G2-tmix/2Á
/
The earlier studies on Markovnikov Sꢀ
/
H and Seꢀ
/
H
90Áacq, with tmix 1Á2 s, and 40.0, ꢁ
/
ꢂ
/
/
/
40.0 (%) field
addition reactions were concentrated on palladium
complexes, while the present work suggests that plati-
num complexes are superior, particularly in where it
concerns the selectivity. Low overall selectivity of
PhSeH addition to activated alkynes and acetylenic
hydrocarbons may be observed due to side reactions of
non-catalyzed addition and double bond isomerization,
respectively.
gradient pulses for G1 and G2, respectively. The further
details as described earlier [32].
The rest of NMR experiments were performed using
pulse sequences supplied by hardware manufacturer.
1
4.3. Detecting H2 with H-NMR
At room temperature (r.t.) PhSeH (15.7 mg, 1ꢃ
mol) was dissolved in 0.5 ml of C6D6 and placed in
NMR tube. Pd(PPh3)4 (57.8 mg, 5ꢃ
10ꢁ5 mol) was
added to the solution immediately changing its’ color to
/
10ꢁ4
/
4. Experimental
dark. Gas evolution occurs for the time period over 10Á
/
15 min. 1H-NMR spectra indicate appearing of H2 peak
at 4.5 ppm, which vanishes after purging the solution
with argon. Authentic H2 sample was prepared by
purging hydrogen from balloon through the C6D6 and
4.1. General
Unless otherwise stated, synthetic work was carried
out under argon atmosphere. The reagents, namely
Pd(PPh3)4 (Aldrich), Pt(PPh3)4 (Acros), Ph2Se2 (Acros),
PhSeH (Acros), alkynes (Acros and Fluka) were
checked with NMR and used as supplied.
dꢂ
/
4.5 ppm was the only new peak appeared.
4.4. Trapping with acid (Mꢂ
/
Pd, Pt)
Ph2Se2 (9.4 mg, 3ꢃ
/
10ꢁ5 mol) and M(PPh3)4 (2ꢃ
/
10ꢁ5 mol) were dissolved in 0.5 ml of C6D6 and the
mixture was heated at 80 8C for 15 min. The 31P{1H}-
NMR spectrum was recorded to insure corresponding
4.2. NMR spectroscopy
oxidative addition products formation. The alkyne HCꢁ
CꢀCH2CH2OH (2.8 mg, 4ꢃ
10ꢁ5 mol) and the acid
CF3COOH (4.6 mg, 4ꢃ
10ꢁ5 mol) were added and the
/
All NMR measurements were performed using a three
channel Bruker DRX500 spectrometer operating at
/
/
1
500.1, 202.5, 125.8 and 95.4 MHz for H, 31P, 13C and
/
77Se nuclei, respectively. The spectra were processed on
a Silicon Graphics workstation using XWINMR 3.0
software package. All 2D spectra were recorded using
inverse triple resonance probehead with active shielded
solution was heated at 80 8C for 3 h.
4.5. Detecting complex Pt(H)(SePh)(PPh3)2 with
NMR spectroscopy
1
Z-gradient coil. H and 13C chemical shifts are reported
relative to the corresponding solvent signals used as
At r.t. PhSeH (7.9 mg, 5ꢃ
0.5 ml of C6D6 and Pt(PPh3)4 (62.2 mg, 5ꢃ
/
10ꢁ5 mol) was dissolved in
10ꢁ5 mol)
internal reference, external 85% H3PO4/H2O (dꢂ
ppm) used for 31P and Ph2Se2/CDCl3 (dꢂ
463.0 ppm)
for 77Se [31].
/0.0
/
/
was added to the solution changing its’ color to orange.
NMR monitoring has shown that the hydride resonance

170
V.P. Ananikov et al. / Journal of Organometallic Chemistry 679 (2003) 162Á172
/
(dꢂ
/
ꢁ
/
8.77 ppm) slowly decrease in intensity upon
5.19; N, 4.24; Se, 23.91. Found: C, 47.20; H, 5.15; N,
4.04; Se, 23.99%. Mass spectrum (EI), m/e 241 [Mꢀ
vanishing after several hours.
ꢁ
/
HOOCꢀ/COOH, 15].
4.6. General synthetic procedure for 8AÁ
/
8D
4.6.4. H2Cꢂ
Yellow oil; 1H-NMR (500 MHz; CDCl3; d, ppm):
7.58 (m, 2H, Ph), 7.30 (m, 3H, Ph), 5.76 (s, 1H, HCꢂ),
5.00 (s, 1H, HCꢂ), 1.85Á1.55 (m, 9H, ꢀC6H10ꢀ), 1.24
(m, 1H, ꢀC6H10ꢀ
). 13C{1H} (126 MHz; CDCl3; d,
ppm): 153.9, 141.6, 135.0, 129.3, 127.9, 114.3 (H2Cꢂ),
), 37.1(CH2), 25.5 (CH2), 22.0 (CH2).
77Se (95 MHz; CDCl3; d, ppm): 376.2. Anal. Calc. for
C14H8OSe: C, 59.79; H, 5.69; Se 28.07. Found: C, 59.56;
H, 6.01; Se, 28.37%. Mass spectrum (EI), m/e 282 [Mꢀ,
20].
/
C(SePh)ꢀ
/
C6H10(OH) (8D)
Phenylselenol (157 mg, 1ꢃ
/
10ꢁ3 mol) was dissolved
in 0.5 ml of toluene giving clear solution. Pt(PPh3)4 or
Pd(PPh3)4 (3 mol.%) was dissolved in the solution
changing the color to orange or dark brown in the
/
/
/
/
/
/
/
former and latter cases, respectively. The alkyne (1.5ꢃ
/
/
10ꢁ3 mol) was added to the solution and reaction
mixture was heated for 13 h at 80 8C in a sealed tube.
After completing the reaction the solvent was removed
on rotor evaporator and the product extracted with 2.0
ml of CHCl3. The product was further purified with
chromatography on silica.
75.1 (ꢀ
/
C(OH)ꢀ
/
Structure elucidation of the products was made
utilizing 2D NOESY, LR-COSY, 1H-13C HSQC,
4.7. Isomerization of 8B to 16B and 17B
1
1H-13C HMBC, H-77Se HMQC NMR experiments.
After purification on silica 8B was placed in NMR
tube with 0.5 ml of CDCl3 and kept at the r.t. NMR
spectra were taken daily to follow isomerization reac-
tion. Half conversion was observed after 24 h, about
97% conversion was achieved after 7 days. The same
4.6.1. H2Cꢂ
/
C(SePh)ꢀ
/
CH2OH (8A)
Yellow oil; 1H-NMR (500 MHz; CDCl3; d, ppm):
7.55 (m, 2H, Ph), 7.30 (m, 3H, Ph), 5.89 (br.s, 1H,
HCꢂ
13C{1H} (126 MHz; CDCl3; d, ppm): 152.8, 141.4,
133.9, 129.3, 127.8, 118.4 (H2Cꢂ
), 66.4(CH2). 77Se (95
/
), 5.44 (s, 1H, HCꢂ
/
), 4.19 (br.s, 2H, ꢀ
/
CH2ꢀ/).
ratio 16B:17B:1.4:1.0 was observed during the iso-
/
1
merization process as determined with H-NMR. Re-
moving chloroform on rotary evaporator gives mixture
of 16B and 17B with no other by-products formed. The
same set of 2D NMR methods was utilized in structure
determination as described in Section 4.6.
/
MHz; CDCl3; d, ppm): 385.6. Anal. Calc. for
C9H10OSe: C, 50.72; H, 4.73; Se 37.05. Found: C,
50.96; H, 4.67; Se, 36.67%. Mass spectrum (EI), m/e
214 [Mꢀ, 15].
aCH2ꢀ
/
bCH2ꢀ
/
gCH2ꢀ
White oil; H-NMR (500 MHz; CDCl3; d, ppm; J,
/
dCH3 (8B)
4.7.1. Z-H3Cꢀ
(16B)
White oil; 1H-NMR (500 MHz; C6D6; d, ppm; J, Hz):
7.45 (m, 2H, Ph), 6.97 (m, 3H, Ph), 5.64 (br.t, 1H, Jꢂ
7.1, HCꢂ), 2.30 (dt, 2H, J1ꢂ7.1, J2ꢂ CH2ꢀ),
7.3, ꢀa
1.98 (br.s, 3H, CH3), 1.36 (tq, 2H, J1ꢂ7.3, J2ꢂ7.3,
ꢀb 7.3, ꢀgCH3). 13C{1H} (126
CH2ꢀ), 0.87 (t, 3H, Jꢂ
MHz; C6D6; d, ppm): 134.9 (ꢂCHꢀ), 133.4, 130.3,
126.9, 129.2, 128.3, 34.3 (ꢀa
CH2ꢀ), 26.8 (CH3ꢀ), 22.9
(ꢀb ), 14.1 (ꢀgCH3). 77Se (95 MHz; C6D6; d, ppm):
CH2ꢀ
/
HCꢂ
/
C(SePh)ꢀ
/
aCH2ꢀ
/
bCH2ꢀ
/
gCH3
4.6.2. H2Cꢂ
/
C(SePh)ꢀ
/
1
Hz): 7.56 (m, 2H, Ph), 7.30 (m, 3H, Ph), 5.50 (br.s, 1H,
/
HCꢂ
ꢀa
CH2ꢀ
1.32 (tq, 2H, J1ꢂ
Jꢂ
7.4, ꢀdCH3). 77Se (95 MHz; CDCl3; d, ppm): 423.5.
Mass spectrum (EI), m/e 240 [Mꢀ, 10].
/
), 5.12 (s, 1H, HCꢂ
), 1.53 (tt, 2H, J1ꢂ
7.5, J2ꢂ
7.4, ꢀg
/
), 2.30 (br.t, 2H, Jꢂ
7.4, J2ꢂ CH2ꢀ
7.5, ꢀb
CH2ꢀ), 0.90 (t, 3H,
/7.4,
/
/
/
/
/
/
/
/
/
/
/),
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
4.6.3. H2Cꢂ
/
C(SePh)ꢀ
/
CH2ꢀ
/
NMe2 (8C)×
/
HOOCꢀ
/
363.8. Anal. Calc. for C11H16Se: C, 60.25; H, 6.74; Se
33.01. Found (E/Z mixture): C, 60.22; H, 6.79; Se,
33.10%. Mass spectrum (EI), m/e 240 [Mꢀ, 10].
COOH
White solid. After completing the reaction and
removing the solvent and unreacted alkyne on rotor
evaporator the crude was dissolved in 3 ml of toluene.
The THF solution of HOOCꢀ
/
COOH (1.5ꢃ
/
10ꢁ3 mol
4.7.2. E-H3Cꢀ
(17B)
White oil; 1H-NMR (500 MHz; C6D6; d, ppm; J, Hz):
7.51 (m, 2H, Ph), 7.01 (m, 3H, Ph), 6.02 (br.t, 1H, Jꢂ
7.4, HCꢂ), 1.92 (br.s, 3H, CH3), 1.87 (dt, 2H, J1ꢂ7.4,
J2ꢂ CH2ꢀ), 1.23 (tq, 2H, J1ꢂ7.3, J2ꢂ7.3,
7.3, ꢀa
ꢀb 7.3, ꢀgCH3). 13C{1H} (126
CH2ꢀ), 0.78 (t, 3H, Jꢂ
MHz; C6D6; d, ppm): 137.4 (ꢂCHꢀ), 133.1, 131.1,
129.4, 128.2, 126.7, 31.7 (ꢀa ), 22.4 (ꢀb
CH2ꢀ CH2ꢀ), 20.4
(CH3ꢀ
), 13.9 (ꢀgCH3). 77Se (95 MHz; C6D6; d, ppm):
471.6. Anal. Calc. for C11H16Se: C, 60.25; H, 6.74; Se,
/
HCꢂ
/
C(SePh)ꢀ
/
aCH2ꢀ
/
bCH2ꢀ
/
gCH3
in 2 ml) was added resulting in immediate white
precipitate formation. The solid was washed with
toluene, THF, extracted with 4 ml of methanol and
dried in vacuum.
/
/
/
1H-NMR (500 MHz; CD3OD; d, ppm;): 7.60 (m, 2H,
/
/
/
/
/
Ph), 7.40 (m, 3H, Ph), 6.07 (br.s, 1H, HCꢂ
HCꢂ
), 3.92 (br.s, 2H, CH2), 2.89 (s, 6H, CH3). 13C{1H}
(126 MHz; CD3OD; d, ppm): 165.9 (CꢂO), 136.1, 133.1,
131.1, 130.2, 128.2, 127.9 (H2Cꢂ), 63.2 (ꢀCH2ꢀ), 43.4
(ꢀCH3). Anal. Calc. for C13H17NO4Se: C, 47.28; H,
/
), 5.59 (s, 1H,
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/

V.P. Ananikov et al. / Journal of Organometallic Chemistry 679 (2003) 162Á
/172
171
33.01. Found (E/Z mixture): C, 60.22; H, 6.79; Se,
33.10%. Mass spectrum (EI), m/e 240 [Mꢀ, 10].
were calculated geometrically and refined using the
riding model. The positions of the other hydrogen
atoms were found from the difference Fourier map.
All calculations were carried out with the use of the
SHELEX-97 program package [35]. The main geometric
parameters are given in Table 2.
4.8. Crystal structure determination
Single crystals of 8C×
/
HOOCꢀ
/
COOH were obtained
by slow evaporation of methanol solution. The samples
were mounted in air on glass fiber using 5 min epoxy
resin. The X-ray intensity data sets were collected on a
Bruker AXS SMART 1000 diffractometer equipped
with a CCD detector (graphite monochromator, 230(2)
K, v scanning technique, scan step was 0.38, frames
were exposed for 30 s) using a standard procedure [33].
The semiempirical absorption correction was applied
[34]. The crystallographic parameters and selected de-
tails of the refinement of structures are given in Table 3.
The structures were solved by direct and Fourier
techniques, and refined by full-matrix least-squares
method with anisotropic thermal parameters for all
non-hydrogen atoms. The positions of the hydrogen
atoms of the phenyl, methyl and methylene substituents
4.9. Theoretical calculations
B3LYP hybrid density functional method and
Lanl2dz ECP basis set were employed as implemented
in GAUSSIAN-98 package [36]. Normal coordinate ana-
lysis was performed to verify stationary points (no
imaginary frequencies) and to calculate DH energies.
The other calculation details are as described earlier [37].
5. Supplementary material
Crystallographic data for the structural analysis has
been deposited with the Cambridge Crystallographic
Data Centre, CCDC No. 205605. Copies of this
information may be obtained free of charge from The
Director, CCDC, 12 Union Road, Cambridge CB2 1EZ,
Table 3
Data collection and processing parameters for the compounds 8C×
/
HOOCꢀCOOH
/
UK (Fax: ꢀ44-1223-336033; e-mail: deposit@ccdc.cam.
/
ac.uk or www: http://www.ccdc.cam.ac.uk).
Parameter
Value
Empirical formula
Formula weight
Temperature (K)
C13H17NO4Se
330.24
230(2)
Acknowledgements
˚
Wavelength (A)
0.71073
Orthorhombic
Pca2(1)
Crystal system
Space group
Unit cell dimensions
The work was carried out with partial support from
the Chemistry and Material Science Branch of the
Russian Academy of Sciences (Program: ‘Theoretical
and experimental investigations of the nature of chemi-
cal bonding and mechanisms of the most important
chemical reactions and processes’). X-ray diffraction
analysis was performed in the Center of X-ray Diffrac-
tion Studies, A.N. Nesmeyanov Institute of Organoele-
ment Compounds, Russian Academy of Sciences,
Moscow.
˚
a (A)
16.525(4)
5.6633(13)
30.171(6)
90
˚
b (A)
˚
c (A)
a (8)
b (8)
90
90
g (8)
Volume (A3)
2823.6(11)
8
Z
Calculated density (Mg mꢁ3
)
1.554
2.669
1344
Absorption coefficient (mmꢁ1
F(0 0 0)
)
Crystal size (mm)
u Range for data collection (8)
Index ranges
0.02ꢃ
2.46Á30.07
235h 5
335l 542
/
0.03ꢃ
/
0.15
35
0.0481]
/
References
ꢁ
ꢁ/
/
/
/23, ꢁ
/
/k 5/7,
/
/
[1] A. Togni, H. Grutzmacher (Eds.), Catalytic Heterofunctionaliza-
¨
tion, Wiley-VCH, Weinheim, 2001.
Reflections collected/unique
11 056/5845 [Rint
ꢂ
/
Completeness to 2uꢂ/30.05
60.2%
Full-matrix least-squares on
F2
[2] I.P. Beletskaya, C. Moberg, Chem. Rev. 99 (1999) 3435.
[3] T. Kondo, T. Mitsudo, Chem. Rev. 100 (2000) 3205.
[4] A. Ogawa, J. Organomet. Chem. 611 (2000) 463.
[5] T. Wirth (Ed.), Organoselenium Chemistry: Modern Develop-
ments in Organic Synthesis, Springer-Verlag, Berlin, New York,
2000.
Refinement method
Data/restraints/parameters
Goodness-of-fit on F2
5845/1/349
1.001
Final R indices [I ꢀ
/
2s(I)]
R1ꢂ
R1ꢂ
0.288(14)
1.785 and ꢁ0.400
/0.0453, wR2ꢂ
/
0.0915
0.0955
R indices (all data)
Absolute structure parameter
/0.0686, wR2ꢂ
/
[6] T.G. Back (Ed.), Organoselenium Chemistry: A Practical Ap-
proach, Oxford University Press, New York, 1999.
[7] C. Paulmier, Selenium Reagents and Intermediates in Organic
Synthesis, Pergamon Press, Oxford, 1986.
Largest difference peak and hole
(e Aꢁ3
/
)

172
V.P. Ananikov et al. / Journal of Organometallic Chemistry 679 (2003) 162Á172
/
[8] S. Patai, Z. Rappoport (Eds.), The Chemistry of Organic
Selenium and Tellurium Compounds, vol. 1Á2, Wiley, New
York, 1986.
[27] R. Ugo, G. La Monica, S. Cenini, A. Serge, F. Conti, J. Chem.
Soc. A (1971) 522.
/
[28] K. Kawakami, Y. Ozaki, T. Tanaka, J. Organomet. Chem. 69
(1974) 151.
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