[Pd(Ar-BIAN)(alkene)]-catalyzed highly chemo-, regio-, and stereoselective semihydrogenation of 1,2-allenyl phosphonates and related compounds

Article abstract of DOI:10.1002/anie.200601366

(Chemical Equation Presented) Often elusive, trisubstituted (Z)-1-alkenyl phosphonates can be prepared by the semihydrogenation of allenyl phosphonates in the presence of Pd complex 1. This reaction, which occurs in high yield with high chemo-, regio-, an

Full text of DOI:10.1002/anie.200601366

Angewandte
Chemie
Catalytic Hydrogenation
DOI: 10.1002/anie.200601366
[
Pd(Ar-BIAN)(alkene)]-Catalyzed Highly
Chemo-, Regio-, and Stereoselective
Semihydrogenation of 1,2-Allenyl Phosphonates
and Related Compounds**
Hao Guo, Zilong Zheng, Fei Yu, Shengming Ma,*
Alexandre Holuigue, Dorette S. Tromp,
Cornelis J. Elsevier,* and Yihua Yu
Allenes are an important class of compounds with many
[
1,2]
applications in organic chemistry.
However, the hydro-
genation of allenes is challenging, as there are issues of
chemo-, regio-, and stereoselectivity to be addressed
[
2d]
(
Scheme 1). Only a very limited number of studies in this
area have been reported, and the selectivity in the reported
[
3]
cases is low.
Scheme 1. The hydrogenation of allenes.
[
*] H. Guo, Z. Zheng, F. Yu, Prof. S. Ma
State Key Laboratory of Organometallic Chemistry
Shanghai Institute of Organic Chemistry
Chinese Academy of Sciences
354 Fenglin Road, Shanghai 200032 (P. R. China)
Fax: (+86)21-6416-7510
E-mail: masm@mail.sioc.ac.cn
A. Holuigue, D. S. Tromp, Prof. C. J. Elsevier
Van’t Hoff Institute for Molecular Sciences
University of Amsterdam
Nieuwe Achtergracht 166, 1018 WV Amsterdam (The Netherlands)
Fax: (+31)20-525-6456
E-mail: elsevier@science.uva.nl
Y. Yu
Key Laboratory of Optical and Magnetic Resonance Spectroscopy
East China Normal University
3663 Zhongshan Road, Shanghai 200062 (P. R. China)
[
**] The Chinese authors acknowledge financial support from the
International Program of the National Natural Science Foundation
of China. This research has also been partially funded by the
National Research School Combination Catalysis (project number:
2000-14) and by the Universiteit van Amsterdam (grant SAP 2255).
We thank Mr. Tao Bai of this group for independently reproducing
representative examples of the work reported herein. Ar-BIAN=
bis(arylimino)acenaphthene.
Supporting information for this article is available on the WWW
under http://www.angewandte.org or from the author.
Angew. Chem. Int. Ed. 2006, 45, 4997 –5000
ꢀ 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
4997

Communications
[
a,b]
One of the authors and co-work-
ers have previously reported the
hydrogenation of alkynes catalyzed
by [Pd(Ar-BIAN)(alkene)] com-
Table 2: Hydrogenation of 2b–j.
plexes
1 (Ar-BIAN = bis(arylimi-
no)acenaphthene) to afford Z-
Entry
Allene
R
Product
Yield [%]
alkenes in excellent yields with high
[
c]
[
4]
1
2
3
4
5
6
7
8
9
0
2b
2b
2c
2d
2e
2 f
2g
2h
2i
Me
Me
tBu(
n-C H
Ph
p-MeOC
p-MeC H
p-NO C H
4
–
n.r.
91
90
94
95
99
93
90
93
91
stereoselectivity. Herein we report
a highly chemo-, regio-, and stereo-
selective hydrogenation of 1,2-
allenyl phosphonates to give di- or
trisubstituted (Z)-1-alkenyl phos-
phonates with the same catalysts.
Such trisubstituted alkenes are oth-
erwise difficult to obtain.
(Z)-3b
Z)-3c
(Z)-3d
(Z)-3e
(Z)-3 f
(Z)-3g
(Z)-3h
(Z)-3i
(Z)-3j
7
15
H
6
4
6
4
2
6
p-MeO CC H
4
H
2
6
1
2j
We first chose the 1,2-allenyl phosphonate 2a as the
model substrate to study the solvent effects of the reaction at
08C. In most solvents, such as diethyl ether, dioxane, N,N-
[a] The reaction was carried out at room temperature with 2 (0.2 mmol)
and 1b (1 mol%) in THF (3 mL) under H2 (1 atm) for 24 h. [b] The
chemo-, regio-, and stereoselectivities were determined by H NMR
spectroscopic analysis of the crude reaction product. [c] The reaction
was conducted with 1a (1 mol%) as the catalyst. n.r.=no reaction.
2
1
dimethyl formamide, dimethyl sulfoxide, CH Cl , CH CCl ,
2
2
3
3
toluene, CH NO , CH OH, AcOH, and Et N, the hydro-
3
2
3
3
genation did not proceed. Fortunately, when the reaction was
conducted in CH CN or THF, only the trisubstituted (Z)-1-
3
alkenyl phosphonate (Z)-3a was formed, in excellent yield
with excellent chemo-, regio-, and stereoselectivity (Table 1,
for the other substrates. Interestingly, the hydrogenation of
2k under these conditions gave the (Z)-1-alkenyl phospho-
nate (Z)-3k in 93% yield as the only product, in which the
isolated allylic C=C bond in 2k had also been hydrogenated,
Table 1: [Pd(Ar-BIAN)(alkene)]-catalyzed hydrogenation of 2a under
[
a,b]
various conditions.
but the conjugated electron-deficient carbon–carbon double
bond remained (Scheme 2). The configuration of the C=C
1
bond in the products 3 was determined by analysis of the H-
1
H NOESY spectra of (Z)-3i.
Entry
Solvent
Catalyst
T [8C]
Yield [%]
1
2
3
4
5
CH CN
1a
1a
1a
1a
1b
20
20
30
50
20
92
94
94
92
94
3
THF
THF
THF
THF
[a] The reaction was carried out at the temperature stated with 2a
Scheme 2. The hydrogenation of 2k.
(
0.2 mmol) and 1a or 1b (1 mol%) in 3 mL of solvent under H (1 atm)
2
for 24 h. [b] The chemo-, regio-, and stereoselectivities were determined
by H NMR spectroscopic analysis of the crude reaction product.
1
The hydrogenation of the 1,3-disubstituted 1,2-allenyl
phosphonate 2l and 1,3,3-trisubstituted 1,2-allenyl phospho-
nates 2m and 2n under the conditions indicated in Table 2
was also studied. Compounds (Z)-3l, (Z)-3m, and (Z)-3n
were formed highly selectively in 92, 95, and 85% yield,
respectively (Scheme 3).
On the basis of these and previous results, a mechanism
for this reaction is proposed in Scheme 4. The catalytic cycle
starts with the loss of the alkene ligand from 1b. Next, the
more electron rich C=C bond in 2 coordinates to palladium in
entries 1 and 2). As the yield in THF was slightly higher than
that in CH CN, THF was chosen as the solvent for this
3
reaction. When we increased the reaction temperature, no
obvious changes were observed (Table 1, entries 3 and 4). It
was also found that the activity of catalyst 1b was the same as
that of 1a for the hydrogenation of 2a (Table 1, entry 5).
We next investigated the hydrogenation of various 1,2-
allenyl phosphonates 2b–j (Table 2). It was surprising to note
that 1a failed to catalyze the hydrogenation of the methyl-
substituted 1,2-allenyl phosphonate 2b (Table 2, entry 1). As
the lack of hydrogenation activity may result from the
stronger coordination of the fumaronitrile ligand, we decided
to attempt the reaction with palladium complex 1b, which has
a more labile alkene ligand. Indeed, 1b catalyzed the partial
hydrogenation reaction to afford alkene (Z)-3b in 91% yield
(
Table 2, entry 2). Therefore, the same conditions were used
Scheme 3. The semihydrogenation of 2l–n.
4
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Angewandte
Chemie
Scheme 5. The semihydrogenation of some related compounds.
tube under a nitrogen atmosphere. The nitrogen atmosphere was
replaced with a hydrogen atmosphere (1 atm), and the solution was
stirred at 208C for 24 h. The reaction mixture was then filtered.
Evaporation of the solvent and flash chromatography on silica gel
Scheme 4. A possible mechanism for this reaction.
(
petroleum ether/diethyl ether 1:2) afforded (Z)-3a (44 mg, 94%) as
1
a liquid. H NMR (300 MHz, CDCl ): d = 6.24 (dtq, J = 0.9, 7.2,
3
5
3
0.7 Hz, 1H), 4.13–3.96 (m, 4H), 2.22–2.12 (m, 2H), 2.03–1.98 (m,
place of the alkene ligand to form a [Pd(Ar-BIAN)(allene)]
H), 1.48–1.38 (m, 2H), 1.35–1.23 (m, 8H), 0.88 ppm (t, J = 7.2 Hz,
1
3
complex 5. In analogy with the mechanism for alkyne
3H); C NMR (CDCl , 75.4 MHz): d = 142.2 (d, J = 11.8 Hz), 129.8
(d, JPC = 170.3 Hz), 61.0 (d, JPC = 5.8 Hz), 35.0 (d, JPC = 12.1 Hz), 31.7
3
P
C
[
4c]
hydrogenation studied by one of us and co-workers, we
propose the heterolytic hydrogen cleavage of 5 to afford the
monohydridopalladium complex 6, which may undergo highly
stereoselective hydropalladation to generate the palladium
hydride 7a or 7b after transfer of the NÀH hydrogen atom to
(d, JPC = 3.0 Hz), 22.2, 16.3 (d, J = 4.4 Hz), 16.2 (d, JPC = 2.6 Hz),
PC
3
1
1
3.8 ppm; P NMR (121.5 MHz, CDCl ): d = 21.0 ppm; IR (neat):
3
+
À1
n˜ = 1632, 1444, 1391, 1245, 1026 cm ; MS :m/z: 234 (M , 9.87), 44
+
+
(100); HRMS(MALDI): m/z calcd for C H O P [M ]: 233.1385;
11 23 3
found: 234.1400.
[
5]
Pd. The final product 3 is produced by reductive elimination
from 7a or 7b. Meanwhile, the catalytically active [Pd(Ar-
BIAN)(allene)] species 5 is regenerated through the inter-
action of 8 with the starting allene. On the basis of the
stereoselectivity observed, we reason that the reaction most
likely proceeds via the intermediate 7a, in which the mutual
trans orientation of the palladium and phosphonate moieties
may determine the stereoselectivity.
This protocol was successfully extended to allenes sub-
stituted with other functionalities, namely, the 1,2-allenyl
phosphine oxide 9, the 1,2-allenyl sulfone 11, and the 2,3-
allenoate 13 (Scheme 5). In these cases the semihydrogena-
tion also proceeds with very high chemo-, regio-, and
stereoselectivity. Note that toluene should be used as the
solvent for the 2,3-allenoate 13.
Received: April 6, 2006
Published online: June 29, 2006
Keywords: alkenes · allenes · homogeneous catalysis ·
.
hydrogenation · palladium
[1] a) Allenes in Organic Synthesis (Eds.: H. F. Schuster, G. M.
Coppola), Wiley, New York, 1984; b) The Chemistry of Ketenes,
Allenes, and Related Compounds, Part 1 (Ed.: S. Patai), Wiley,
New York, 1980; c) Modern Allene Chemistry (Eds.: N. Krause,
A. S. K. Hashmi), Wiley-VCH, Weinheim, 2004.
[
2] For reviews, see: a) K. K. Wang, Chem. Rev. 1996, 96, 207; b) R.
Zimmer, C. Dinesh, E. Nandanan, F. Khan, Chem. Rev. 2000, 100,
3067; c) J. Marshall, Chem. Rev. 2000, 100, 3163; d) A. S. K.
Hashmi, Angew. Chem. 2000, 112, 3737; Angew. Chem. Int. Ed.
In conclusion, we have demonstrated a novel, highly
chemo-, regio-, and stereoselective [Pd(Ar-BIAN)(alkene)]-
2000, 39, 3590; e) X. Lu, C. Zhang, Z. Xu, Acc. Chem. Res. 2001,
[
6,7]
34, 535; f) R. Bates, V. Satcharoen, Chem. Soc. Rev. 2002, 31, 12;
g) S. Ma, Handbook of Organopalladium Chemistry for Organic
Synthesis (Ed.: E. Negishi), Wiley, New York, 2002, p. 1491; h) L.
Sydnes, Chem. Rev. 2003, 103, 1133; i) S. Ma, Acc. Chem. Res.
2003, 36, 701; j) M. Tius, Acc. Chem. Res. 2003, 36, 284; k) L.-L.
Wei, H. Xiong, R. P. Hsung, Acc. Chem. Res. 2003, 36, 773; l) L.
Brandsma, N. A. Nedolya, Synthesis 2004, 735; m) F. Pan, C. Fu, S.
Ma, Chin. J. Org. Chem. 2004, 24, 1168; n) S. Ma, Chem. Rev.
catalyzed hydrogenation of 1,2-allenyl phosphonates
other 1,2-allenyl compounds to form di- or trisubstituted (Z)-
-alkenyl phosphonates, sulfones, and esters in excellent
and
1
yields. Further studies in this field are being carried out in our
laboratories, including investigations into synthetic applica-
tions of the reaction.
2005, 105, 2829; o) S. Ma in Topics in Organometallic Chemistry
(Ed.: J. Tsuji), Springer, Heidelberg, 2005; p) C. J. Elsevier in
Experimental Section
Houben-Weyl Methoden der Organischen Chemie, Stereoselective
Synthesis, Vol. E21a (Eds.: G. Helmchen, R. W. Hoffmann, J.
Mulzer, E. Schaumann), Thieme, Stuttgart, 1995, pp. 537 – 566.
Typical procedure: Catalyst 1b (1 mg, 0.002 mmol), 2a (46 mg,
0
.2 mmol), and anhydrous THF (3 mL) were added to a Schlenk
Angew. Chem. Int. Ed. 2006, 45, 4997 –5000
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Communications
[
3] a) D. G. Pete, N. Munisamappa, J. Org. Chem. 1961, 26, 3518;
b) D. Devaprabhakara, P. D. Gardner, J. Am. Chem. Soc. 1963, 85,
48; c) J. M. Brown, Chem. Ind. 1963, 1689; d) P. Down, J. Chem.
6
Soc. Chem. Commun. 1965, 568; e) G. Nagendrappa, D. Devap-
rabhakara, Tetrahedron Lett. 1970, 4243; f) R. Baudouy, J. Gore,
Tetrahedron 1975, 31, 383; g) L. Crombie, P. A. Jenkins, D. A.
Mitchard, J. Chem. Soc. Perkin Trans. 1 1975, 1081; h) F.
Hammerschmidt, G. Bovermann, K. Bayer, Liebigs Ann. Chem.
1990, 1055.
[
4] a) M. W. Laren, C. J. Elsevier, Angew. Chem. 1999, 111, 3926;
Angew. Chem. Int. Ed. 1999, 38, 3715; b) J. W. Sprengers, J.
Wassenaar, N. D. Clement, K. J. Cavell, C. J. Elsevier, Angew.
Chem. 2005, 117, 2062; Angew. Chem. Int. Ed. 2005, 44, 2026;
c) A. M. Kluwer, T. S. Koblenz, T. Jonischkeit, K. Woelk, C. J.
Elsevier, J. Am. Chem. Soc. 2005, 127, 15470.
[
[
[
5] A. Dedieu, S. Humbel, C. J. Elsevier, C. Grauffel, Theor. Chem.
Acc. 2004, 112, 305.
6] R. Asselt, C. J. Elsevier, W. J. J. Smeets, A. L. Spek, Inorg. Chem.
1994, 33, 1521.
7] H. Altenbach, R. Korff, Tetrahedron Lett. 1981, 22, 5175.
5
000 www.angewandte.org
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