Hydroselenation and carboselenation of electron-deficient alkynes with isolable (Hydrido)(selenolato)platinum(II) complexes and a selenaplatinacycle bearing a triptycene skeleton

Article abstract of DOI:10.1002/ejoc.200901408

The reaction of [PtH(SeTrip) (PPh₃)₂] (Trip = 9-triptycyl) (3) with dimethyl acetylenedicarboxylate (DMAD) or methyl propiolate gave hydroselenation syn adducts. The reaction of [PtH(SeTrip)(dppe)J [dppe = 1,2-bis(diphenylphosphanyl)ethane], which has a stronger phosphane σ-donor ligand than 3, with DMAD gave both syn and anti adducts. The reaction of 3 and DMAD in the presence of PPh₃ yielded no adducts. These observations indicate that, in the hydroselenation, the dissociation of a PPh3 ligand from 3 is a key step. The selenaplatinacycle 6, which is a thermal reaction product of 3, reacted with DMAD to give the carboselenation product, 1H-2-benzoselenin 7, which was also formed by the reaction of TripSeH with DMAD.

Full text of DOI:10.1002/ejoc.200901408

FULL PAPER
DOI: 10.1002/ejoc.200901408
Hydroselenation and Carboselenation of Electron-Deficient Alkynes with
Isolable (Hydrido)(selenolato)platinum(II) Complexes and a
Selenaplatinacycle Bearing a Triptycene Skeleton
Akihiko Ishii,*[a] Hitomi Kamon,[a] Keiko Murakami,[a] and Norio Nakata[a]
Keywords: Platinum / Insertion / Hydride ligands / Phosphane ligands / Selenium
The reaction of [PtH(SeTrip)(PPh3)2] (Trip = 9-triptycyl) (3)
with dimethyl acetylenedicarboxylate (DMAD) or methyl
propiolate gave hydroselenation syn adducts. The reaction of
[PtH(SeTrip)(dppe)] [dppe = 1,2-bis(diphenylphosphanyl)-
ethane], which has a stronger phosphane σ-donor ligand
adducts. These observations indicate that, in the hydroselen-
ation, the dissociation of a PPh3 ligand from 3 is a key step.
The selenaplatinacycle 6, which is a thermal reaction product
of 3, reacted with DMAD to give the carboselenation prod-
uct, 1H-2-benzoselenin 7, which was also formed by the re-
than 3, with DMAD gave both syn and anti adducts. The re- action of TripSeH with DMAD.
action of 3 and DMAD in the presence of PPh3 yielded no
reductive elimination from which yields the vinyl selenide
Introduction
and [Pt(PPh3)2].[2a,9] As far as we know, however, there have
been no reports on a direct, stoichiometric reaction between
(hydrido)(selenolato)palladium(II) or -platinum(II) com-
plexes with alkynes.
Regioselective and/or stereoselective, transition-metal-
catalyzed hydroselenation of terminal alkynes,[1–3] as well as
other chalcogenation reactions of alkynes,[4–6] are impor-
tant reactions that provide synthetically useful vinyl selen-
ides [Equation (1)]. Carboselenation and carbothiolation[7]
are also important synthetic reactions from the point of
view of providing C–Se and C–C bonds in one step.[8] Con-
cerning the mechanism for hydroselenation catalyzed by
group 10 metals, Ogawa proposed a possible mechanism in-
volving ligand exchange of [Pd(SePh)2Ln] (L = pyridine),
formed by the reaction of [Pd(OAc)2] with 2 PhSeH and 2
L, with a terminal alkyne, followed by insertion of the al-
kyne into the Pd–Se bond to give [(Z)-2-selenovinyl]palladi-
um(II) complexes.[1b] The protonolysis of the vinyl PdII
complexes with PhSeH gives the Markovnikov-type adduct
(1,1-disubstituted alkene) accompanying the regeneration
of the catalyst.[1b] Ananikov proposed a similar mechanism
for the Pd(PPh3)4-catalyzed hydroselenation that involved
both trans-[PdH(SePh)(PPh3)2] and dinuclear PdII com-
plexes, cis- and trans-[{Pd(SePh)(PPh3)}2(µ-SePh)2], instead
of mononuclear diselenolato complexes.[2a] In the case
of the Pt(PPh3)4-catalyzed hydroselenation with PhSeH,
(1)
Scheme 1. Catalytic cycle for the hydroselenation proposed by An-
anikov.[4b]
Ananikov observed
a
key intermediate,
trans-
[PtH(SePh)(PPh3)2] (1), by 1H NMR spectroscopy and pro-
We recently succeeded in the isolation of stable
posed the catalytic cycle shown in Scheme 1.[2a] (Hydrido)- (hydrido)(selenolato)platinum(II) complexes with cis con-
platinum(II) complex 1 undergoes insertion of the alkyne figuration of two phosphane ligands by the reaction of 9-
into the Pt–Se bond to give 2 (syn-selenoplatination), the triptyceneselenol (TripSeH, Trip
= 9-triptycyl) with
[Pt(C2H4)(PPh3)2][10a] [Equation (2)] or [Pt(dppe or
dppf)][10b] [dppe = 1,2-bis(diphenylphosphanyl)ethane; dppf
= 1,1Ј-bis(diphenylphosphanyl)ferrocene] (Figure 1).[11] The
investigation of the stoichiometric reaction of (hydrido)-
(selenolato)platinum(II) complexes with alkynes is quite in-
[a] Department of Chemistry, Graduate School of Science and
Engineering, Saitama University,
255 Shimo-okubo, Sakura-ku, Saitama 338-8570, Japan
Fax: +81-48-858-3394
E-mail: ishiiaki@chem.saitama-u.ac.jp
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A. Ishii, H. Kamon, K. Murakami, N. Nakata
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formative for clarifying the course of the hydroselenation.
Here, we report the reaction of two (hydrido)(selenolato)-
platinum(II) complexes, [PtH(SeTrip)(PPh3)2] (3) and
[PtH(SeTrip)(dppe)] (4), with electron-deficient alkynes and
the related carboselenation reactions.
(2)
Figure 2. ORTEP drawing of (E)-5 at the 30% probability level.
Selected bond lengths [Å] and angles [°]: Se1–C2 1.890(3), Se1–C7
1.953(3), C1–C2 1.335(5), C1–C3 1.468(5), C2–C5 1.506(5); C2–
Se1–C7 106.15(14), Se1–C2–C1 130.0(3), Se1–C2–C5 106.9(2), C1–
C2–C5 123.1(3), C2–C1–C3 120.8(3).
Figure 1. [PtH(SeTrip)(dppe)] (left, 4) and [PtH(SeTrip)(dppf)]
(right).
(δ = 5.43 and 6.27 ppm) indicated the trans stereochemistry.
The structure of (E)-9 was finally confirmed by X-ray crys-
tallography (Figure 3).[12] The stereoselectivity found here
contrasts with that reported by Ananikov and co-workers
for the reaction between methyl propiolate and PhSeH in
the presence of Pt(PPh3)4 in toluene at 80 °C, which gave a
1:7 (E)/(Z) mixture of 9 through a noncatalytic reaction.[2a]
They also reported that reactions of terminal alkynes with
PhSeH under similar conditions gave Markovnikov-type
products [H2C=C(SePh)R] regioselectively in the case of 2-
propyn-1-ol, 1-hexyne, 3-dimethylaminopropyne, and 1-eth-
ynylcyclohexanol, and anti-Markovnikov-type products, (E)
and (Z) isomers, in the case of phenylacetylene.[2a] The reac-
tion of 3 with 1-hexyne, phenylacetylene, diphenylacetylene,
or methyl 2-butynoate, did not yield hydroselenation ad-
ducts, which is probably due to the steric hindrance of the
bulky 9-triptycyl group and to the strong coordinating abil-
ity of this alkaneselenolato ligand compared with the ben-
zeneselenolato ligand.
Results and Discussion
Hydroselenation
The reaction of [PtH(SeTrip)(PPh3)2] (3) with dimethyl
acetylenedicarboxylate (DMAD) in benzene at 60 °C for 2 h
gave syn adduct (E)-5 in 24% yield, together with selena-
platinacycle 6 (7%), 1H-2-benzoselenin derivative 7 (2%),
diselenide 8 (12%), 3 (13%), and [Pt(dmad)(Ph3P)2] (79%)
[Equation (3)]. The structure of (E)-5 was determined un-
ambiguously by X-ray crystallography (Figure 2).[12] The
selenaplatinacycle 6 is formed as a thermal reaction product
of 3 as reported previously.[10a] 1H-2-Benzoselenin 7 is a
carboselenation product of DMAD with 6 or TripSeH, as
discussed in the next section.
(4)
(3)
The regio- and stereoselective formation of (E)-5 and
(E)-9 supports the syn insertion of DMAD or methyl pro-
Similarly, the reaction of 3 with methyl propiolate was piolate into the Pt–Se bond of 3 to give the [(Z)-2-seleno-
carried out in benzene at 60 °C for 3 h to produce syn ad- vinyl]platinum(II) complex, followed by reductive elimi-
duct (E)-9 in 36% yield, together with [Pt(mp)(PPh3)2] nation. On the other hand, the reaction of [PtH(Se-
(64%), selenaplatinacycle 6 (24%), and diselenide 8 (35%) Trip)(dppe)] (4) with DMAD in benzene proceeded slug-
1
[Equation (4)]. In the H NMR spectrum of (E)-9, a large gishly at 60 °C, and heating in refluxing benzene for 38 h
coupling constant (16 Hz) between the two vinylic protons was necessary to bring about complete consumption of 4
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Hydro- and Carboselenation of Electron-Deficient Alkynes
Scheme 2. Proposed mechanism for the reaction of [PtH-
(SeTrip)(PPh3)2] (3) with DMAD to give the syn adduct (E)-5.
Figure 3. ORTEP drawing of (E)-9 at the 30% probability level.
The hexane solvent molecule is omitted. Selected bond lengths [Å]
and angles [°]: Se1–C2 1.888(2), Se1–C5 1.959(2), C1–C2 1.326(3),
C1–C3 1.468(3); C2–Se1–C5 97.08(9), Se1–C2–C1 125.26(18), C2–
C1–C3 122.8(2).
Figure 4 summarizes the bond lengths around the Pt
atoms of 3[10a] and 4[10b] obtained from X-ray crystallo-
graphic data. The Pt–P bonds in 3 [2.2474(12) and
2.3295(12) Å] are longer than those in 4 [2.2190(19) and
2.3093(16) Å], indicating the weaker coordination of PPh3
to the Pt atom compared to that of dppe, due to the weaker
σ-donor ability and larger steric hindrance. This consider-
ation is based on the structures of 3 and 4 in the crystalline
state and is in agreement with their reactivities in solution.
In both complexes, the Pt–P bonds trans to the H ligand
are longer by 0.08–0.09 Å than those trans to the TripSe
ligand, which is probably due to the P(1) ligands, suffering
large steric repulsion from both cis ligands, in addition to
a stronger trans influence of the H ligand. This would lead
to a stronger trans effect of the H ligand observed for the
PPh3 dissociation step. Incidentally, the Pt–Se bond
[2.4376(8) Å] in 4 is only slightly longer (0.01 Å) than that
in 3 [2.4272(5) Å]. If the insertion of DMAD into the Pt–
Se bonds of 3 and 4 occurred in the four-coordinate states,
almost similar reactivity of both complexes toward DMAD
might be observed.
to yield (E)-5 (11%), (Z)-5 (21%), 1H-2-benzoselenin 7
(3%), and diselenide 8 (31%) [Equation (5)]. These prod-
ucts are considered to form by the reaction of TripSeH and
DMAD as described in the next section.
(5)
The difference in reactivities between [PtH(SeTrip)-
(PPh3)2] (3) and [PtH(SeTrip)(dppe)] (4) toward DMAD is
attributed to the weaker coordination ability of PPh3 com-
pared to dppe, that is, the dissociation of one phosphane
ligand (PPh3) from 3 is essential for the hydroselention reac-
tion. The dissociation of PPh3 from 3 should be depressed
by the addition of PPh3, which was evidenced by the reac-
tion of 3 with DMAD in the presence of additional PPh3
(2 equiv.); this impeded the formation of (E)-5 to give dis-
elenide 8 (39%), 3 (35%), and [Pt(dmad)(PPh3)2] (53%).
Thus, as depicted in Scheme 2, dissociation of one of the
PPh3 ligands from 3 occurs first to give coordination-unsat-
Figure 4. Bond lengths [Å] around the Pt atoms of [PtH-
(SeTrip)(PPh3)2] (3)[10a] and [PtH(SeTrip)(dppe)] (4).[10b]
Similar prior dissociation of a phosphane ligand was re-
urated intermediate 10, where the ligand trans to H would ported for the insertion of an alkyne into the Pt–S bond in
be detached owing to the stronger trans effect of the H li- trans-[Pt(SAr)2(PPh3)2][13] and the Pt–Si bond in cis-
gand than that of the selenolato ligand. The larger trans [Pt(SiR3)2(PMe2Ph)2].[14] Kuniyasu and Kambe succeeded
influence of hydrido ligands compared to the selenolato li- in the isolation of (selenolato)(2-selenovinyl)plati-
gands in 3 and 4 has been discussed on the basis of NMR num(II)[15a] and -palladium(II) complexes[15b] correspond-
spectroscopic data in solution and X-ray structures in the ing to 2 and 11. In the present hydroselenation, we have
crystalline state.[10] Then, 10 undergoes insertion of DMAD neither isolated nor observed 11.
and re-coordination of PPh3 to yield the (hydrido)(2-sel-
We examined whether hydrido complex 3 serves as a cat-
enoalkenyl)platinum(II) intermediate 11, from which re- alyst for the hydroselenation of DMAD with TripSeH.
ductive elimination provides the syn adduct (E)-5 and Thus, when TripSeH and DMAD were heated at 60 °C in
[Pt(PPh3)2].
benzene in the presence of 10 mol-% of 3, both (E)-5 (19%)
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and (Z)-5 (30%) were obtained, together with 7 (1%) and data; in the 1H NMR spectrum, signals of two cis-vinyl pro-
diselenide 8 (25%) [Equation (6)]. This result can largely tons in (Z)-9 appeared at δ = 6.53 and 7.72 ppm with a
be explained by the thermal reaction between TripSeH and coupling constant of 9.6 Hz. Because the reaction of Trip-
DMAD. [Pt(PPh3)2], generated during the reductive elimi- SeH with methyl propiolate in the absence of 3 proceeded
nation step, does not work as a catalyst, because it would very slowly under similar conditions to give a mixture of
undergo coordination of DMAD, preferentially furnishing (E)-9, (Z)-9 and recovered TripSeH in a ratio of 7:5:88, an
[Pt(dmad)(Ph3P)2], which is persistent under the reaction alternative catalytic process promoting the addition of Trip-
conditions.
SeH to methyl propiolate is presumably operating here;
however, the details are unclear.
(6)
(7)
The catalytic ability of 3 in the reaction of TripSeH with
methyl propiolate was also examined. When the reaction
was carried out in benzene at 60 °C for 5 h, both (E)-9
(21%) and (Z)-9 (38%) were obtained [Equation (7)]. The
structure of (Z)-9 was determined from the spectroscopic
Carboselenation
As mentioned above, we observed the formation of 1H-
2-benzoselenin derivative 7, which is an anticipated car-
boselenation product of DMAD with selenaplatinacycle 6.
Indeed, complex 6 reacted with DMAD in refluxing xylene
to give 7 in good yield [Equation (8)]. Unexpectedly, the
reaction of TripSeH with DMAD in benzene at 60 °C led
to the formation of 7 (18%) together with (E)-5 (16%), (Z)-
5 (18%), and diselenide 8 (28%) [Equation (9)]. Heating of
(E)-5 or (Z)-5 under similar conditions, in the absence or
presence of DMAD or TripSeH, did not yield any 7. These
observations suggest that, in the reaction of PtH(Se-
Trip)(dppe) (4) with DMAD [Equation (5)], 4 did not react
directly with DMAD, but instead eliminated TripSeH,
which reacted with DMAD to yield a mixture of 7, (E)-5,
and (Z)-5. Since 2,6-di-tert-butyl-4-methylphenol, a radical
inhibitor, prevented the formation of 7 in the reaction of
TripSeH and DMAD, a radical process may play a role in
the formation of 7. However, the details are not clear at
present.
Figure 5. ORTEP drawing of 7 at the 30% probability level. Se-
lected bond lengths [Å], angles [°], and torsion angles [°]. 7A: Se1–
C1 1.896(4), Se1–C9 1.961(3), C1–C2 1.344(6), C1–C23 1.483(4),
C2–C3 1.467(4), C2–C25 1.508(6), C3–C4 1.411(6), C3–C8
1.400(5), C4–C5 1.373(4), C5–C6 1.392(6), C6–C7 1.385(6), C7–C8
1.391(4), C7–C22 1.524(6), C8–C9 1.543(5), C23–O1 1.197(5),
C23–O2 1.342(5), O2–C24 1.447(4), C25–O3 1.192(5), C25–O4
1.342(5), O4–C26 1.444(5); C1–Se1–C9 101.1(1), Se1–C1–C2
125.4(3), Se1–C1–C23 113.0(3), C2–C1–C23 121.5(3), C1–C2–C3
125.6(3), C1–C2–C25 118.2(3), C3–C2–C25 116.3(3), C2–C3–C4
118.8(3), C2–C3–C8 123.8(3), C4–C3–C8 117.5(3), C3–C4–C5
121.9(3), C4–C5–C6 120.0(3), C5–C6–C7 119.0(3), C6–C7–C8
121.4(3), C6–C7–C22 123.9(3), C8–C7–C22 114.7(3), C3–C8–C7
120.1(3), C3–C8–C9 128.1(3), C7–C8–C9 111.8(3), Se1–C9–C8
115.3(2), C1–C23–O1 125.6(4), C1–C23–O2 110.5(3), O1–C23–O2
124.0(4), C23–O2–C24 116.0(3), C2–C25–O3 124.1(3), C2–C25–O4
111.0(3), O3–C25–O4 124.8(4), C25–O4–C26 114.3(3); C2–C1–
C23–O2 –10.6(6), C1–C2–C25–O3 –87.2(5), C3–C8–C9–Se1 3.4(4).
7B: C28–C27–C51–O7 –1.5(6), C27–C28–C49–O5 96.3(4), C29–
C34–C35–Se2 –0.4(5).
(8)
(9)
The structure of 7 was elucidated by its 1H, 13C, and
77Se NMR spectroscopic data, and finally verified by X-ray
crystallography.[12] As depicted in Figure 5, there are two
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Hydro- and Carboselenation of Electron-Deficient Alkynes
independent molecules (7A and 7B) in the unit cell, the geo- whereas the reaction of 6 with diphenylacetylene, 4-octyne,
metries of which are slightly different in dihedral angles in- or methyl 2-butynoate did not occur, and the starting mate-
cluding the Se atom and torsion angles of methoxycarbonyl rial was recovered almost quantitatively. As selenaplatinacy-
groups to the respective 1H-2-benzoselenin ring. The C3– cle 6 itself is stable under the reaction conditions (no de-
C8–C9–Se1 dihedral angle in 7A is 3.4(4)° and the corre- composition took place when heated in toluene at 80 °C
sponding C29–C34–C35–Se2 dihedral angle in 7B is overnight), the above observations suggest an interaction
–0.4(5)°, indicating that the Se-containing ring in 7A is between 6 and methyl propiolate leads to the decomposi-
slightly more puckered than that in 7B. The 3- and 4-meth- tion of 6.
oxycarbonyl groups are almost coplanar and perpendicular,
respectively, to the 1H-2-benzoselenin ring, where the tor-
sion angles are –10.6(6)° (C2–C1–C23–O1) and –87.2(5)°
(C1–C2–C25–O3) for 7A and –1.5(6)° (C28–C27–C51–O7)
and 96.3(4)° (C27–C28–C49–O5) for 7B. Intermolecular
short contact distances are also observed in the crystalline
Conclusions
We have shown for the first time that the reactions of
isolable (hydrido)(selenolato)platinum(II) complex 3 with
activated alkynes (DMAD and methyl propiolate) proceed
state. As shown in Figure 6, the distances Se1···Se1
through syn addition. The initial dissociation of one of the
(3.462 Å) and Se2···Se2 (3.401 Å) are both shorter than the
PPh3 ligands from 3 is necessary for the hydroselenation.
These results provide a necessary condition for the hydro-
selenation of alkynes with selenols catalyzed by Pt0 com-
plexes and offer an insight into the reaction mechanism.
Carboselenation of DMAD with selenaplatinacycle 6
yielded 1H-2-benzoselenin derivative 7, which was also
formed by the reaction of TripSeH with DMAD.
sum of the van der Waals radii (3.80 Å).[16] The benzene
ring of the 1H-2-benzoselenin moiety adopts a π-stacking
arrangement, where the C4···C30 distance is 3.334 Å.
Experimental Section
General: Melting points were determined with a Mel-Temp capil-
lary-tube apparatus. 1H (400 MHz), 13C (100.7 MHz), and 77Se
(76.3 MHz) NMR spectra were obtained with Bruker DRX400 or
DPX400 spectrometers. IR spectra were recorded with a Perkin–
Elmer System 2000 FTIR spectrometer. Mass spectra were deter-
mined with a JEOL JMS-700AM spectrometer operating at 70 eV
in the EI mode. X-ray crystallography was performed with a Bruker
AXS SMART diffractometer. The intensity data were collected at
103 K by employing graphite-monochromated Mo-Kα radiation (λ
= 0.71073 Å), and the structures were solved by direct methods
and refined by full-matrix least-squares procedures on F2 for all
reflections (SHELX-97).[17] Gel permeation chromatography
(GPC) was performed with a Japan Analytical Industry LC-908.
Elemental analyses were performed at the Molecular Analysis and
Life Science Center of Saitama University.
Reaction of [PtH(SeTrip)(PPh3)2] (3) with DMAD: A mixture of
3 (32.0 mg, 0.0304 mmol) and DMAD (4.4 mg, 0.0309 mmol) in
benzene (2.5 mL) was heated at 60 °C under argon for 2 h. The
residue was subjected to column chromatography (acidic silica gel;
dichloromethane) to give diselenide 8 (1.2 mg, 12%), a mixture of
selenaplatinacycle 6 and 3 (6.5 mg; 6: 7%; 3: 13%), and a mixture
of (E)-5 and 1H-2-benzoselenin 7 [3.8 mg; (E)-5: 24%; 7: 2%] in
this order. The yields of 6, 3, (E)-5, and 7 were calculated on the
basis of the integral ratios in the 1H NMR spectra of the respective
mixtures. The yield of [Pt(dmad)(PPh3)2][18] (79%) was estimated
from the integral ratio in the 1H NMR spectrum (δ = 3.31 ppm for
CO2Me) of the reaction mixture.
Figure 6. A part of the crystal packing of 7 showing (a) the short
contacts between selenium atoms and π-stacking and (b) a top view
showing stacking of two benzene rings: Se1···Se1 3.462 Å, Se2···Se2
3.401 Å, C4···C30 3.334 Å.
Reaction of [PtH(SeTrip)(PPh3)2] (3) with Methyl Propiolate: To a
solution of 3 (81.8 mg, 0.0777 mol) in benzene (7 mL), was added
a solution of methyl propiolate in benzene (0.378 , 0.420 mL,
0.159 mmol) under argon. The mixture was heated at 60 °C for 3 h,
then the solvent was removed in vacuo. The residue was subjected
to column chromatography (acidic silica gel; dichloromethane) to
Carboselenation of other alkynes with selenaplatinacycle
6 did not progress as expected. Heating of 6 with methyl
propiolate (5.6 equiv.) either in refluxing benzene or in
chlorobenzene at 50 °C resulted in decomposition of 6, give a mixture of selenaplatinacycle 6 and diselenide 8 (28.5 mg; 6:
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A. Ishii, H. Kamon, K. Murakami, N. Nakata
24%; 8: 35%, based on the integral ratio) and (E)-9 (11.6 mg, for 5 h. The solvent was removed under reduced pressure, and the
FULL PAPER
36%). A signal assignable to the CH3 group of [Pt(mp)(PPh3)2][19]
was detected at δ = 3.32 ppm in the 1H NMR spectrum of the
reaction mixture; the ratio of (E)-9/[Pt(mp)(PPh3)2] was 9:16 based
on the integral ratio. An analytical sample of (E)-9 was obtained
by purification with GPC.
residue was subjected to column chromatography (silica gel; hex-
ane/dichloromethane, 1:2 and then dichloromethane) to give dis-
elenide 8 (24.4 mg, 25%), (Z)-5 (43 mg, 30%), and (E)-5 (27.9 mg,
20%) in this order.
Reaction of TripSeH with Methyl Propiolate in the Presence of
Methyl (E)-3-(9-Triptycylseleno)propenoate [(E)-9]: Colorless crys-
[PtH(SeTrip)(PPh3)2] (3) (0.1 Equiv.): To a solution of TripSeH
tals; m.p. 178–180 °C. 1H NMR (400 MHz, CDCl3, 25 °C): δ = (98.5 mg, 0.295 mmol) and 3 (31.1 mg, 0.0295 mg) in benzene
3.68 (s, 3 H, OCH3), 5.43 (s, 1 H, Trip-10-H), 6.27 (d, J = 16 Hz, (3 mL) under argon, was added a solution of methyl propiolate in
1 H, vinyl-H), 7.00–7.09 (m, 6 H, Ar-H), 7.41–7.47 (m, 6 H, Ar- benzene (1.2 , 2.00 mL, 2.36 mmol). The mixture was heated at
H), 8.18 (d, J = 16 Hz, 1 H, vinyl-H) ppm. 13C NMR (100.6 MHz,
CDCl3, 25 °C): δ = 51.61 (CH3), 54.10 (CH), 61.52 (C), 122.30
(CH), 123.60 (CH), 123.83 (CH), 125.28 (C), 126.01 (CH), 141.12
(CH), 143.72 (C), 145.27 (C), 164.94 (C) ppm. 77Se NMR
60 °C for 5 h, then the solvent was removed under reduced pressure.
The residue was subjected to column chromatography (silica gel;
hexane/dichloromethane, 1:2 and then diethyl ether) to give a mix-
ture of TripSeH and diselenide 8 (18.7 mg), (Z)-9 (47.2 mg, 38%),
and (E)-9 (26.2 mg, 21%) in this order. An analytical sample of
(Z)-9 was obtained by purification with GPC.
(76.3 MHz, CDCl , 25 °C): δ = 250.3 ppm. IR: ν = 1715 (C=O)
˜
3
cm–1. C24H18O2Se (417.37): calcd. C 69.07, H 4.35; found C 68.90,
H 4.44. Crystallographic data: C24H18O2Se·0.5C6H14; MW =
460.43; triclinic; space group P1; a = 8.1389(5), b = 11.4869(8), c
= 12.1267(8) Å, α = 88.351(2), β = 72.4300(10), γ = 84.0920(10)°;
V = 1075.10(12) Å3; Z = 2; Dcalcd. = 1.422 gcm–3; R1 [IϾ2σ(I)] =
0.0341, wR2 = 0.0873 (all data) for 4201 reflections, 273 parameters,
GOF = 1.073.
Methyl (Z)-3-(9-Triptycylseleno)propenoate [(Z)-9]: Colorless crys-
tals; m.p. 170–172 °C. 1H NMR (400 MHz, CDCl3, 25 °C): δ =
3.92 (s, 3 H, OCH3), 5.43 (s, 1 H, Trip-10-H), 6.53 (d, J = 9.6 Hz,
1 H, vinyl-H), 6.99–7.08 (m, 6 H, Ar-H), 7.41–7.57 (m, 6 H, Ar-
H), 7.72 (d, J = 9.6 Hz, 1 H, vinyl-H) ppm. 13C NMR (100.6 MHz,
CDCl3, 25 °C): δ = 51.8 (CH3), 54.2 (CH), 60.3 (C), 117.2 (CH),
123.6 (CH), 123.9 (CH), 125.1 (CH), 125.8 (CH), 144.4 (CH), 145.6
¯
Reaction of [PtH(SeTrip)(dppe)] (4) with DMAD: A mixture of 4
(30.2 mg, 0.0326 mmol) and DMAD (34.7 mg, 0.244 mmol) in ben-
zene (3 mL) was heated under reflux for 38 h. The solvent was re-
moved in vacuo, and the residue was subjected to preparative TLC
(silica gel, dichloromethane) to give diselenide 8 (3.4 mg, 31%), a
mixture of 4 and 6 (2.3 mg), (Z)-5 (3.2 mg, 21%), and a mixture of
(E)-5 and 7 (2.1 mg; 11% and 3%, respectively). An analytical sam-
ple of (Z)-5 containing 0.5 equiv. of H2O in 1 equiv of (Z)-5 (de-
(C), 145.8 (C), 168.1 (C) ppm. IR (KBr): ν = 1714 (C=O) cm–1.
˜
C24H18O2Se (417.37): calcd. C 69.07, H 4.35; found C 68.67, H
4.30.
Reaction of TripSeH with Methyl Propiolate: To a solution of Trip-
SeH (35.6 mg, 0.107 mmol) in benzene (2 mL) under argon, was
added a solution of methyl propiolate in benzene (1.2 , 0.105 mL,
0.128 mmol). The mixture was heated at 60 °C for 5 h, then the
1
tected by H NMR) was obtained by recrystallization from a sol-
1
solvent was removed under reduced pressure. The H NMR spec-
vent mixture (dichloromethane/hexane). A pure sample of (E)-5
was obtained by purification with GPC.
trum, which was measured with bibenzyl (2.1 mg, 0.012 mmol) as
the internal standard, showed the formation of (Z)-9 (4%) and (E)-
Dimethyl 2-(9-Triptycylseleno)maleate [(E)-5]: Colorless crystals; 9 (1%), together with TripSeH (89%).
1
m.p. 210–212 °C. H NMR (400 MHz, CDCl3, 25 °C): δ = 3.57 (s,
Reaction of Selenaplatinacycle 6 with DMAD: A mixture of 6
3 H, OCH3), 4.02 (s, 3 H, OCH3), 5.29 (s, 1 H, vinyl-H), 5.43 (s, 1
H, Trip-10-H), 7.01–7.08 (m, 6 H, Ar-H), 7.41–7.43 (m, 3 H, Ar-
H), 7.51–7.53 (m, 3 H, Ar-H) ppm. 13C NMR (100.6 MHz, CDCl3,
25 °C): δ = 51.80 (CH3), 53.42 (CH3), 54.04 (CH), 63.11 (C), 123.61
(CH), 123.64 (CH), 124.00 (CH), 125.30 (CH), 126.24 (CH), 141.42
(C), 142.24 (C), 144.95 (C), 163.85 (C), 167.01 (C) ppm.
C26H20O4Se (475.40): calcd. C 65.68, H 4.24; found C 65.50, H
4.32. Crystallographic data: C26H20O4Se; MW = 475.40; triclinic;
(91.9 mg, 0.0874 mmol) and DMAD (92.6 mg, 0.652 mmol) in xy-
lene (16 mL) was heated under reflux under argon for 5 h, and then
the solvent was removed in vacuo. The residue was subjected to
column chromatography (acidic silica gel; dichloromethane) to give
1H-2-benzoselenin 7 (27.4 mg, 66%). [Pt(dmad)(PPh3)2] was de-
1
tected in the H NMR spectrum of the reaction mixture, and the
yield was estimated to be 12% on the basis of the integral ratio to
7. An analytical sample of 7 was obtained by recrystallization from
¯
space group P1; a = 9.4998(9), b = 9.6335(9), c = 13.1369(12) Å, α
1
a solvent mixture (diethyl ether/dichloromethane/hexane). The H
= 74.787(2), β = 69.956(2), γ = 71.244(2)°; V = 1053.67(17) Å3; Z
= 2; Dcalcd. = 1.498 gcm–3; R1 [IϾ2σ(I)] = 0.0457, wR2 = 0.1145
(all data) for 3912 reflections, 282 parameters, GOF = 1.043.
NMR spectrum showed that the sample contained 1 equiv. of H2O
in 1 equiv. of 7.
2,3-Bis(methoxycarbonyl)-1-selena-7H-7,11b[1Ј,2Ј]-benzeno-1H-
benzo[de]anthracene (1H-2-Benzoselenine 7): Colorless crystals;
Dimethyl 2-(9-Triptycylseleno)fumarate [(Z)-5]: Colorless crystals;
m.p. 209 °C (dichloromethane/hexane). 1H NMR (400 MHz,
CDCl3, 25 °C): δ = 2.50 (s, 3 H, OCH3), 3.93 (s, 3 H, OCH3), 5.37
(s, 1 H, Trip-10-H), 6.99–7.02 (m, 7 H, Ar-H and vinyl-H), 7.35–
7.38 (m, 3 H, Ar-H), 7.59–7.61 (m, 3 H, Ar-H) ppm. 13C NMR
(100.6 MHz, CDCl3, 25 °C): δ = 51.43 (CH3), 52.24 (CH3), 54.09
(CH), 62.81 (C), 123.08 (CH), 123.70 (CH), 124.39 (CH), 124.63
(CH), 125.51 (CH), 144.76 (C), 145.09 (C), 146.33 (C), 165.65 (C),
166.69 (C) ppm. 77Se NMR (76.3 MHz, CDCl3, 25 °C): δ =
346.7 ppm. C26H20O4Se·0.5H2O (484.41): calcd. C 64.47, H 4.37;
found C 64.31, H 4.09.
1
m.p. 234 °C (Et2O/dichloromethane/hexane). H NMR (400 MHz,
CDCl3, 25 °C): δ = 3.92 (s, 3 H, OCH3), 3.97 (s, 3 H, OCH3), 5.40
(s, 1 H, 7-H), 6.81 (d, J = 8 Hz, 1 H, 4-H or 6-H), 7.01 (t, J =
8 Hz, 1 H, 5-H), 7.05 [t, J = 8 Hz, 2 H, 9(4Ј)-H or 10(5Ј)-H], 7.12
[dt, J = 8, 1 Hz, 2 H, 10(5Ј)-H or 9(4Ј)-H], 7.41 [d, J = 8 Hz, 2 H,
8(3Ј)-H or 11(6Ј)-H], 7.45 (d, J = 8 Hz, 1 H, 6-H or 4-H), 7.83 [d,
J = 8 Hz, 2 H, 11(6Ј)-H or 8(3Ј)-H] ppm. 13C NMR (100.6 MHz,
CDCl3, 25 °C): δ = 52.8 (CH3), 53.4 (CH3), 54.0 (CH), 54.9 (C),
118.5 (C), 123.6 (CH), 124.9 (CH), 125.42 (CH), 125.44 (CH),
125.7 (CH), 126.46 (C), 126.53 (CH), 126.6 (CH), 135.5 (CH),
136.8 (CH), 144.0 (C), 145.9 (C), 146.0 (C), 164.3 (C), 169.1 (C)
ppm. 77Se NMR (76.3 MHz, CDCl3, 25 °C): δ = 136.8 ppm. IR
Reaction of TripSeH with DMAD in the Presence of [PtH(SeTrip)-
(PPh3)2] (3) (0.1 Equiv.):
0.299 mmol), DMAD (64 mg, 0.45 mmol), and
0.0287 mmol) in benzene (2 mL) was heated at 50 °C under argon
A
mixture of TripSeH (99.7 mg,
3
(30.2 mg,
(KBr): ν = 1718, 1736 cm–1. C H O Se·H O (491.40): calcd. C
˜
26 18
4
2
63.55, H 4.10; found C 63.35, H 3.81. Crystallographic data:
1658
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© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2010, 1653–1659

Hydro- and Carboselenation of Electron-Deficient Alkynes
¯
For a review, see; o) G. Perin, E. J. Lenardão, R. G. Jacob,
R. B. Panatieri, Chem. Rev. 2009, 109, 1277–1301.
C26H18O4Se; MW = 473.36; triclinic; space group P1; a =
12.6203(7), b = 12.8827(7), c = 13.7795(8) Å, α = 103.7120(10), β
= 103.4520(10), γ = 103.0010(10)°; V = 2021.6(2) Å3; Z = 4; Dcalcd.
= 1.555 gcm–3; R1 [IϾ2σ(I)] = 0.0399, wR2 (all data) = 0.0973 for
7490 reflections, 563 parameters, GOF = 1.015.
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Reaction of TripSeH with DMAD: A mixture of TripSeH (36.7 mg,
0.110 mmol) and DMAD (0.8  in benzene, 0.160 mL,
0.132 mmol) in benzene (2 mL) was heated at 60 °C under argon
for 6 h. The solvent was removed in vacuo, and the residue was
subjected to column chromatography (acidic silica gel; hexane/
dichloromethane, 1:2) to give 2 (10.6 mg, 28%), (Z)-5 (9.4 mg,
18%), 1H-2-benzoselenin 7 (3.8 mg, 7%), and a mixture of 7 and
(E)-5 (14.4 mg; 11% and 16%, respectively) in this order.
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This work was supported by a Grant-in-Aid for Science Research
(C) (No. 21550035) and a Grant-in-Aid for Scientific Research on
Priority Areas (Nos. 19027014 and 20036013, Synergy of Elements)
from the Ministry of Education, Culture, Sports, Science and Tech-
nology, Japan.
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Received: December 4, 2009
Published Online: February 11, 2010
Eur. J. Org. Chem. 2010, 1653–1659
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
1659