A novel one-pot reaction: Zwitterionic rhodium complex-catalyzed hydroaminovinylation of vinyl sulfones and a vinylphosphonate [1]

Full text of DOI:10.1021/ja010923+

J. Am. Chem. Soc. 2001, 123, 7719-7720
7719
Table 1. Hydroaminovinylation of Methyl Vinyl Sulfone in the
Presence of Syngas and Isopropylaminea
A Novel One-Pot Reaction: Zwitterionic Rhodium
Complex-Catalyzed Hydroaminovinylation of Vinyl
Sulfones and a Vinylphosphonate
Yong-Shou Lin, Bassam El Ali,† and Howard Alper*
Center for Catalysis Research and InnoVation
Department of Chemistry
UniVersity of Ottawa, 10 Marie Curie
Ottawa, Ontario, Canada K1N 6N5
yield (mol %)b
entry
L (mol %)
T (°C)
CO/H2 (psi)
4a
5a
ReceiVed April 10, 2001
1
2c
3
(BINAP (3)
dppb (3)
dppe (3)
dppm (3)
PPh3 (6)
PCy3 (6)
80
80
80
80
80
80
80
50
80
80
100/100
100/100
100/100
100/100
100/100
100/100
100/100
100/100
100/500
100/100
96 (86)
92 (87)
93
17
61
10
0
68
95
4
3
7
49
25
61
100
32
5
It is well-known that functionalized vinyl sulfones and phos-
phonates have wide applications in organic synthesis.1 Nitrogen-
containing vinyl sulfones and vinyl phosphonates are important
intermediates involved in biochemical synthesis.2,3 The develop-
ment of new processes for synthesizing amino-substituted unsat-
urated sulfones and phosphonates has attracted considerable
attention.1b One approach is the hydroaminomethylation of olefins
as a one-pot synthesis of amines.4,5 Recently, we have found that
hydroaminomethylation of aryl-substituted ethylenes affords
mainly branched chain amines, under relatively mild conditions,
by using the zwitterionic rhodium complex [Rh+(cod)(η6-
PhBPh3)-] (1) as a catalyst.6 These results stimulated us to explore
the reactions of vinyl sulfones and a phosphonate under hydro-
aminomethylation conditions. A novel type of one-pot reaction,
hydroaminoVinylation, took place. We now report the results of
this investigation.
4d
5c,e
6c,e
7
none
8
(BINAP (3)
(BINAP (3)
(BINAP (3)
9
10f
94
6
a Reaction conditions: methyl vinyl sulfone (1 mmol), isopropyl-
amine (1.2 mmol), 1 (0.01 mmol), phosphine, THF (5 mL), 24 h. b The
yields were determined by 1H NMR and GC (the isolated yield is given
in parentheses). c A small amount of MeSO2CH2CH2SO2Me (<4 mol
%) was formed. d Methyl vinyl sulfone (34%) was recovered. e Un-
identified byproducts were formed (14% in entry 5, and 29% in entry
6). f The reaction was carried out for 1 h.
Table 2. Hydroaminovinylation of Methyl Vinyl Sulfone in the
Presence of Various Aminesa
Reaction of methyl vinyl sulfone (2), isopropylamine (3a), and
1:1 carbon monoxide/hydrogen (total pressure of 200 psi), with
1 mol % of 1 and 3 mol % of BINAP as an added phosphine
ligand, for 24 h at 80 °C, afforded the sulfonylated enamine 4a
in 86% isolated yield (eq 1 and Table 1, entry 1).7 The Michael-
† Present address: KFUPM, Chemistry Department, Dhahran 31261, Saudi
Arabia.
(1) (a) Metzner, P.; Thuillier, A. Sulfur Reagents in Organic Synthesis;
Academic Press: London, 1994. (b) Minami, T.; Motoyoshiya, J. Synthesis
1992, 333. (c) Cadogan, J. I. G. Organophosphorus Reagents in Organic
Synthesis; Academic Press: London, 1979.
(2) For recent examples related to sulfones, see: (a) Ravindran, B.;
Sakthivel, K.; Suresh, C. G.; Pathak, T. J. Org. Chem. 2000, 65, 2637. (b)
Overkleeft, H. S.; Bos, P. R.; Hekking, B. G.; Gordon, E. J.; Ploegh, H. L.;
Kessler, B. M. Tetrahedron Lett. 2000, 41, 6005. (c) Joyeau, R.; Maoulida,
C.; Guillet, C.; Frappier, F.; Teixeira, A. R. L.; Schrevel, J.; Santana, J.;
Grellier, P. Eur. J. Med. Chem. 2000, 35, 257. (d) Clark, R. B.; Pearson, W.
H. Org. Lett. 1999, 1, 349. (e) Schmidtke, G.; Holzhutter, H. G.; Bogyo, M.;
Kairies, N.; Groll, M.; de Giuli, R.; Emch, S.; Groettrup, M. J. Biol. Chem.
1999, 274, 35734. (f) Xia, L. H.; Kilb, J. Wex, H.; Li, Z. Q.; Lipyansky, A.;
Breuil, V.; Stein, L.; Palmer, J. T.; Dempster, D. W.; Bromme, D. Biol. Chem.
1999, 380, 679. (g) Bogyo, M.; Shin, S.; Mcmaster, J. S.; Ploegh, H. L. Chem.
Biol. 1998, 5, 307. (h) Caturla, F.; Na´jera, C. Tetrahedron Lett. 1996, 37,
2833. (i) Smith, D. C.; Fuchs, P. L. J. Org. Chem. 1995, 60, 2692.
(3) For examples related to phosphonates, see: (a) Thomas, A. A.;
Sharpless, K. B. J. Org. Chem. 1999, 64, 8379. (b) Stowasser, B.; Budt, K.-
H.; Li, J.-Q.; Peyman, A.; Ruppert, D. Tetrahedron Lett. 1992, 33, 6625. (c)
Patel, D. V.; Rielly-Gauvin, K.; Ryono, D. E. Tetrahedron Lett. 1990, 31,
5587. (d) Patel, D. V.; Rielly-Gauvin, K.; Ryono, D. E. Tetrahedron Lett.
1990, 31, 5591. (e) Zygmunt, J. Tetrahedron 1985, 41, 4979. (f) Engel, R.
Chem. ReV. 1977, 77, 349.
yield (mol %)b
entry
amine
4
5
1
2
3
4
5
6
butylamine (3b)
tert-butylamine (3c)
cyclohexylamine (3d)
benzylamine (3e)
aniline (3f)
66 (43, 4b)
100 (89, 4c)
90 (75, 4d)
87 (67, 4e)
100 (73, 4f)
84 (66, 4g)
34 (5b)
0
10 (5d)
13 (5e)
0
HNEt2 (3g)
16 (5g)
a Reaction conditions: methyl vinyl sulfone (1 mmol), amine (1.2
mmol), 1 (0.01 mmol), (BINAP (0.03 mmol), THF (5 mL), 80 °C for
1 h. b The yields were determined by 1H NMR and GC (isolated yield
is given in parentheses).
type addition product 5a was a minor byproduct of the reaction.
To our knowledge, this is the first example of the one-pot
formation of a sulfonated enamine from the corresponding vinyl
sulfone catalyzed by a rhodium complex. Various reaction
conditions were examined for this hydroaminovinylation reaction
(Table 1). For example, other chelating phosphine ligands, such
as 1,4-bis(diphenylphosphino)butane (dppb) and 1,2-bis(diphen-
ylphosphino) ethane (dppe) also afforded 4a in good yields (entries
2 and 3). In contrast, 5a was the principal product using bis-
(diphenylphosphino)methane (dppm) as the ligand (entry 4). The
(4) Eilbracht, P.; Ba¨rfacker, L.; Buss, C.; Hollmann, C.; Kitsos-Rzychon,
B. E.; Kranemann, C. L.; Rische, T.; Roggenbuck, R.; Schmidt, A. Chem.
ReV. 1999, 99, 3329 and references therein.
(5) (a) Kranemann, C. L.; Eilbracht, P. Eur. J. Org. Chem., 2000, 2367.
(b) Rische, T.; Eilbracht, P. Tetrahedron 1999, 55, 1915. (c) Rische, T.; Mu¨ller,
K.-S.; Eilbracht, P. Tetrahedron 1999, 55, 9801. (d) Zimmermann, B.; Herwig,
J.; Beller, M. Angew. Chem., Int. Ed. 1999, 38, 2372. (e) Breit, B. Tetrahedron
Lett. 1998, 39, 5163. (f) Dong, Y.; Busacca, C. A. J. Org. Chem. 1997, 62,
6464. (g) To¨ro¨s, S.; Ge´mes-Pe´csi, L.; Heil, B.; Maho´, S.; Tuba, Z. J. Chem.
Soc., Chem. Commun. 1992, 858.
(6) Lin, Y.-S.; Alper, H. Tetrahedron Lett. 2001, 42, 2423.
(7) See Supporting Information for general procedures and details on the
1H, 13C, 31P NMR, MS, and HRMS of the enamines.
10.1021/ja010923+ CCC: $20.00 © 2001 American Chemical Society
Published on Web 07/12/2001

7720 J. Am. Chem. Soc., Vol. 123, No. 31, 2001
Communications to the Editor
reason for this change in behavior is not clear. While the use of
a monodentate phosphine, triphenylphosphine, resulted in the
formation of 4a in 61% yield (entry 5), the more basic and
sterically encumbered ligand, tricyclohexylphosphine, was of little
value here (entry 6). In the absence of a phosphine ligand, 5a
was formed exclusively (entry 7). Consequently BINAP, dppb,
and dppe are effective ligands for the hydroaminovinylation
reaction. A decrease of the reaction temperature to 50 °C resulted
in reducing the selectivity to form 4a (entry 8). Interestingly,
reduction of the double bond in 4a did not occur even though
the hydrogen pressure was increased to 500 psi (entry 9). It is
noteworthy that the hydroaminovinylation of sulfones can be
completed in only 1 h, that is, one does not have to let the reaction
proceed for 24 h (entry 10).
The scope of the reaction was examined with a number of
amines and vinyl sulfones. Fine yields of 4b-4g were obtained
using primary amines (RNH2, R ) n-C4H9, t-C4H9, C6H11, PhCH2,
and Ph, Table 2, entries 1-5) and diethylamine (entry 6).
Hydroaminovinylation of ethyl vinyl sulfone gave the corre-
sponding unsaturated enamine 7 in good yield, with dppb as the
ligand (eq 3). Phenyl vinyl sulfone is less active toward
rus-containing vinylated amine 17a-h, in 63-88% isolated yields
(eq 6, Table 3). The primary amines, except aniline, gave 17 as
Table 3. Hydroaminovinylation of Diethyl Vinylphosphonate in
the Presence of Aminesa
entry
amine
yield (mol %)b
ratio trans/cis
1
2
isopropylamine (3a)
butylamine (3b)
tert-butylamine (3c)
benzylamine (3e)
aniline (3f)
HNEt2 (3g)
piperidine (3h)
100 (83, 17a)
98 (63, 17b)
97 (66, 17c)
96 (88, 17e)
95 (70, 17f)
100 (84, 17g)
100 (82, 17h)
88:12
86:14
88:12
80:20
100:0
100:0
100:0
3
4c
5d
6
7
a Reaction conditions: diethylvinylphosphonate (1 mmol), amine (1.2
mmol), 1 (0.01 mmol), dppb (0.03 mmol), THF (5 mL), 80 °C for 5 h.
1
b The yields were determined by H NMR and GC (the isolated yield
is given in parentheses). c (EtO)2P(O)CH(CH3)CHO (4%) was formed.
d 5% of unidentified byproducts.
hydroaminovinylation compared with methyl vinyl sulfone. The
addition reaction is the principal process when less than 4 equiv
of (BINAP was used for the reactions (eq 4). However,
1
a mixture of trans- and cis-isomers (based on H and 31P NMR
spectroscopy), with good selectivity for the trans-isomer. The fact
that only trans-enamines were formed when the secondary amines,
diethylamine and piperidine, were used indicates that the proton
attached to the nitrogen atom plays an important role in forming
the cis-isomer when the primary amine is employed. Intramo-
lecular hydrogen-bonding between the H atom of the NH group
and the O atom of the PdO moiety may be responsible for the
formation of some of the cis-isomer in the case of primary amines.
The formation of six-membered lithiated enaminoalkylphospho-
nates has been reported in the preparation of R,â-unsaturated
R-substituted aldehydes.8 The weakly electron-withdrawing phenyl
group in aniline probably diminishes hydrogen-bond formation
in 17f, which may be why only the trans-isomer is formed here.
In conclusion, a new one-pot hydroaminovinylation reaction
has been achieved for the synthesis of sulfonated and phospho-
nated enamines using the zwitterionic rhodium complex 1 together
with a chelating phosphine ligand as the catalyst. The regio- and
stereoselectivity of the reactions are often excellent.
increasing the amount of the ligand to 8 equiv significantly
impacted the degree of hydroaminovinylation, leading to the
formation of 10 in 78% yield as the major product (eq 4). Use of
8 mol % dppb as the ligand instead of (BINAP resulted in the
formation of 10 in a similar yield. Likewise, a sulfoxide, phenyl
vinyl sulfoxide, was converted to the corresponding enamine 14
in high yield by the described methodology (89%, eq 5).
The hydroaminovinylation of diethyl vinylphosphonate pro-
ceeded smoothly in the presence of a primary or secondary amine,
using 1/dppb as the catalyst system, affording only the phospho-
Acknowledgment. We are grateful to the Natural Sciences and
Engineering Research Council of Canada for support of this research.
Supporting Information Available: General procedures, 1H, 13C,
31P NMR, MS, and HRMS of enamines 4, 7, 10, 14, and 17 (PDF). The
material is available free of charge via the Internet at http://pubs.acs.org.
JA010923+
(8) Tay, M. K.; Aboujaoude, E. E.; Collignon, N.; Savignac, Ph. Tetra-
hedron Lett. 1987, 28, 1263.