Rhodium catalyzed conjugated addition of unsaturated carbonyl compounds by triphenylbismuth in aqueous media and under an air atmosphere

Article abstract of DOI:10.1016/S0040-4039(00)02176-6

In the presence of a rhodium catalyst, α,β-unsaturated esters and ketones react with triphenylbismuth in aqueous media and under an air atmosphere to give the corresponding conjugated addition products in high yields.

Full text of DOI:10.1016/S0040-4039(00)02176-6

TETRAHEDRON
LETTERS
Pergamon
Tetrahedron Letters 42 (2001) 781–784
Rhodium catalyzed conjugated addition of unsaturated carbonyl
compounds by triphenylbismuth in aqueous media and under an
air atmosphere
Sripathy Venkatraman and Chao-Jun Li*
Department of Chemistry, Tulane University, New Orleans, LA 70118, USA
Received 1 November 2000; revised 20 November 2000; accepted 27 November 2000
Abstract—In the presence of a rhodium catalyst, a,b-unsaturated esters and ketones react with triphenylbismuth in aqueous media
and under an air atmosphere to give the corresponding conjugated addition products in high yields. © 2001 Published by Elsevier
Science Ltd.
most attentions have been focused on Grignard-type
reactions, the corresponding conjugated addition has
been explored much less. Previously, Luche et al.
reported a zinc–copper couple mediated conjugated
addition of unsaturated carbonyl compounds and
nitriles with alkyl iodides under sonication conditions
in aqueous ethanol.6 Giese and co-workers studied the
diastereoselectivity of these reactions.7 Recently, we
reported a Grignard-type phenylation of aldehydes in
water in which phenyltin derivatives (trimethyl and
tributyl) reacted effectively with aldehydes in water and
under an atmosphere of air to give nucleophilic addi-
tion products in high yields in the presence of a cata-
lytic amount of rhodium catalyst.8 The intriguing
insensitivity of the rhodium catalytic system towards air
and water led us to explore the potentials of other
synthetically useful reactions under similar conditions.9
Herein we wish to report that in the presence of a
rhodium catalyst, a,b-unsaturated esters and ketones
react with triphenylbismuth in aqueous media to give
the corresponding conjugated addition products in high
yields under an air atmosphere (Eq. (1)).10
Recently interest has been growing in carrying out
organic reactions in water because of its natural abun-
dance and the inherent advantages of using water as a
solvent. Various reactions that are traditionally carried
out in organic solvent have now been equally successful
or more effective in aqueous media.1 Such develop-
ments are exemplified by the aqueous Barbier–Grignard
type reactions that traditionally are considered highly
sensitive towards water.2 An important method that is
closely related to Grignard reactions for forming car-
bonꢀcarbon bonds is through the conjugated addition
of an organometallic reagent to unsaturated carbonyl
derivatives.3 Such reactions are generally carried out by
using copper reagents or catalysts.4 As in the case of
Grignard-type reactions, for conjugated additions
based on organometallic reagents, it is generally
accepted that strict anhydrous reaction conditions are
required.
On the other hand, the significance of performing
metal-mediated carbonꢀcarbon bond formation reac-
tions in water has been recognized recently.5 While
R
O
O
cat. Rh(I)
R'
+
Ph3Bi
R
R'
H2O/THF/12 h
50°C
(1)
air atmosphere
3
1
2
* Corresponding author.
0040-4039/01/$ - see front matter © 2001 Published by Elsevier Science Ltd.
PII: S0040-4039(00)02176-6

782
S. Venkatraman, C.-J. Li / Tetrahedron Letters 42 (2001) 781–784
To begin our study, triphenylbismuth was stirred with
yield (together with biphenyl). The reaction was equally
successful at room temperature albeit took a much
longer reaction time for a high conversion (2–3 days).
Cationic Rh(COD)2BF4 was also effective as the cata-
lyst. Various conjugated carbonyl compounds were
thus examined under the same reaction conditions with
Rh2(COD)2Cl2 (Table 1). In all cases when a disubsti-
ethyl acrylate and
a
catalytic amount of
a
Rh2(COD)2Cl2 (5 mol%) at 50°C in water.11 A compli-
cated mixture was obtained (including mono- and
bisphenylation products). However, when ethyl croto-
nate was used instead of acrylate, a smooth reaction
occurred to give the conjugated product in 80% isolated
Table 1. Rhodium catalyzed reaction of triphenylbismuth with unsaturated carbonyl compounds in aqueous media
Entry
Product (3)
Carbonyl Derivative (1)
Yield (%)
O
O
1
11
OEt
OEt
O
O
OEt
OEt
80
70
2
3
O
O
OMe
OMe
O
O
80
70
4
OMe
OMe
O
O
O
5
6
O
O
O
84
O
O
7
8
40a
75
CO2Et
CO2Et
CO2Et
CO2Et
9
74
68
O
OMe
OMe
O
10
11
OMe
O
O
73
HO
OMe
CO2Me
HO
12
13
nr
nr
O
All reactions were carried out at 50ºC and yields were isolated ones after column chromatography on silica gel.
a: Carried out at room temperature and the yield was based on H NMR measurement of crude material.

S. Venkatraman, C.-J. Li / Tetrahedron Letters 42 (2001) 781–784
783
L
Media; John Wiley & Sons: New York, 1997. See also:
Li, C. J. Chem. Rev. 1993, 93, 2023; Lubineau, A.;
Auge, J.; Queneau, Y. Synthesis 1994, 741; Organic Syn-
thesis in Water; Grieco, P. A., Ed.; Blackie Academic &
Professional: Glasgow, 1998; Cornils, B.; Wiebus, E.
Chemtech 1995, 25, 33; Hermann, W. A.; Kohlpainter,
C. W. Angew. Chem., Int. Ed. Engl. 1993, 32, 1524;
Kuntz, E. G. Chemtech 1987, 17, 570.
Ph3Bi
O
Ph-Rh-BiPh2
L
R
R'
+ H2O
R
O
L
R'
Rh(I)
L
2. Kharasch, M. S.; Reinmuth, O. Grignard Reactions of
Nonmetallic Substances; Prentice-Hall: New York, 1954.
3. Taylor, R. J. K. Synthesis 1985, 364.
+ Ph2BiOH
4. For reviews, see: Posner, G. H. An Introduction to Syn-
thesis using Organocopper Reagents; Wiley: New York,
1980; Lipshutz, B. H. In Organometallics in Synthesis,
Schlosser, M. Ed.; Wiley: New York, 1994, p. 283. Pal-
ladium, nickel, rhodium, and ruthenium compounds
have also been used as catalysts for conjugated addition
reactions, see: Cho, C. S.; Motofusa, S.; Ohe, K.;
Uemura, S.; Shim, S. C. J. Org. Chem. 1995, 60, 883;
Ikeda, S.; Cui, D. M.; Sato, Y. J. Am. Chem. Soc. 1999,
121, 4712; Sawamura, M.; Hamashima, H.; Ito, Y. J.
Am. Chem. Soc. 1992, 114, 8295; Trost, B. M. Angew.
Chem., Int. Ed. Engl. 1995, 34, 259; Qi, S.; Moro, M.;
Ono, S.; Inoue, Y. Chem. Lett. 1998, 83; Ohe, T.; Wak-
ita, T.; Motofusa, S.; Cho, C. S.; Ohe, K.; Uemura, S.
Bull. Chem. Soc. Jpn. 2000, 73, 2149.
5. For reviews, see: Li, C. J.; Chan, T. H. Tetrahedron
1999, 55, 11149; Li, C. J. Tetrahedron 1996, 52, 5643;
Chan, T. H.; Isaac, M. B. Pure Appl. Chem. 1996, 68,
919.
6. (a) Petrier, C.; Dupuy, C.; Luche, J. L. Tetrahedron
Lett. 1986, 27, 3149; (b) Luche, J. L.; Allavena, C.
Tetrahedron Lett. 1988, 29, 5369; (c) Dupuy, C.; Petrier,
C.; Sarandeses, L. A.; Luche, J. L. Synth. Commun.
1991, 21, 643; (d) Luche, J. L.; Allavena, C.; Petrier, C.;
Dupuy, C. Tetrahedron Lett. 1988, 29, 5373; (e)
Pietrusiewicz, K. M.; Zablocka, M. Tetrahedron Lett.
1988, 29, 937.
7. (a) Giese, B.; Damm, W.; Roth, M.; Zehnder, M. Syn-
lett 1992, 441; (b) Erdmann, P.; Schafer, J.; Springer,
R.; Zeitz, H. G.; Giese, B. Helv. Chim. Acta 1992, 75,
638; (c) Roth, M.; Damm, W.; Giese, B. Tetrahedron
Lett. 1996, 37, 351.
8. Meng, Y.; Li, C. J. J. Am. Chem. Soc. 2000, 120, 9538.
9. For other water and air tolerant transition-metal cata-
lyzed reactions reported from our group, see: Venkatra-
man, S.; Li, C. J. Org. Lett. 1999, 1, 1133;
Venkatraman, S.; Li, C. J. Tetrahedron Lett. 2000, 41,
4831; Li, C. J.; Meng, Y.; Yi, X. H.; Ma, J. H.; Chan,
T. H. J. Org. Chem. 1998, 63, 7498; Wang, D.; Chen,
D. L.; Haberman, J. X.; Li, C. J. Tetrahedron 1998, 54,
5129; Wang, D.; Li, C. J. Synth. Commun. 1998, 28,
507; Li, C. J.; Meng, Y.; Yi, X. H.; Chan, T. H. J. Org.
Chem. 1997, 62, 8632; Li, C. J.; Wang, D.; Chen, D. L.
J. Am. Chem. Soc. 1995, 117, 12867.
10. Recently, rhodium catalyzed conjugated additions on
a,b-unsaturated esters with arylboronic acids were
reported in aqueous dioxane at 100°C under an inert gas
atmosphere, however, no reaction occurred for hydroxy
bearing substrates. Sakuma, S.; Sakai, M.; Itooka, R.;
Miyaura, N. J. Org. Chem. 2000, 65, 5951 and refer-
ences cited therein.
Scheme 1. Tentative mechanism for the rhodium catalyzed
conjugated addition of triphenylbismuth to unsaturated car-
bonyl compounds in aqueous media.
tuted unsaturated CꢁC was involved, the reaction pro-
ceeded smoothly to generate the desired conjugated
addition product. Interestingly, the use of tri-substi-
tuted double bonds shut down the reaction completely.
Both ketones (linear and cyclic) and esters are effective
as the electron-withdrawing functional groups. The use
of conjugated nitriles, acids, and aldehydes led to either
the failure of the conjugated reaction or a mixture of a
variety of products. Compounds bearing a hydroxyl
group reacted as expected and did not require any
protection (entry 11). Scheme 1 outlines a tentative
mechanism in which rhodium serves as a catalyst for
the conjugated addition.12 In conclusion, a highly effec-
tive aqueous and air-stable rhodium catalyzed conju-
gated addition of a,b-unsaturated carbonyl compounds
was developed by using triphenylbismuth. The scope,
mechanism, and synthetic applications of this novel
reaction are under investigation.
A typical experimental procedure is as follows: A mix-
ture of cyclohex-2-en-1-one (100 mg, 1.04 mmol),
triphenylbismuth (504 mg, 1.14 mmol), and bis(1,4-
cyclooctadiene)dirhodium dichloride (25 mg, 5 mol%)
in 4 mL water/THF (7:3) was capped and stirred at
50°C (oil bath temperature) for 12 h. Upon cooling, the
reaction mixture was extracted with ether. The com-
bined organic fractions were dried over MgSO4 and
concentrated. The residue was purified by column chro-
matography on silica gel (eluent: hexane/ethyl acetate=
20:1 to 10:1) to give 3-phenylcyclohexanone (151 mg,
84% yield).
Acknowledgements
We are grateful to NSF (CAREER Award), the NSF-
EPA joint program for a sustainable environment, and
Louisiana Board of Regents for partial support of our
research.
References
1. For general reviews on organic reactions in water, see:
Li, C. J.; Chan, T. H. Organic Reactions in Aqueous
.

784
S. Venkatraman, C.-J. Li / Tetrahedron Letters 42 (2001) 781–784
11. Previously, bismuth has been used for allylation of alde-
hydes and immonium cations: Wada, M.; Ohki, H.;
Akiba, K. Y. Bull. Chem. Soc. Jpn. 1990, 63, 1738 and J.
Chem. Soc., Chem. Commun. 1987, 708; Katritzky, A. R.;
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25, 2751; Minato, M.; Tsuji, J. Chem. Lett. 1988, 2049.
12. The oxidative addition of CꢀBi bond to Rh was proposed
earlier, see: Cho, C. S.; Yoshimori, Y.; Uemura, S. Bull.
Chem. Soc. Jpn. 1995, 68, 950.
.