J. Mazuela et al. / Tetrahedron: Asymmetry 21 (2010) 2153–2157
2157
3
. Conclusions
COST D40 and the Swiss National Research Foundation (Grant No.
00020-113332) for their financial support.
2
A biaryl-based monophosphoroamidite L1–L4a–f and amino-
phosphine L5–L7a–f ligand library was tested to determine its ef-
fects on the asymmetric Rh-catalyzed hydroformylation of several
vinylarenes and heterocyclic olefins. Our results indicated that
selectivity strongly depended on the type of functional group, the
substituents and the configurations at both the biaryl moiety and
the amine group, and the substrate type. For vinylarenes S1–S5
and the heterocyclic olefin 2,5-dihydrofuran S6, enantioselectivi-
ties (ees up to 46%) were best with ligand L1a, whereas for 4,7-
dihydro-1,3-dioxepin substrates S8 and S9 enantioselectivities
References
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(
Yamamoto, H., Eds.; Springer: Berlin, 1999; Vol. 382,. Chapter 11 (d) Godard, C.;
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Ojima, I., Ed.; New Jersey; Wiley, 2010; p 799. Chapter 10.
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2004, 15, 2113; (b) Breit, B. Top. Curr. Chem. 2007, 279, 139; (c) Klosin, J.; Landis,
(
ees up to 58%) were best with ligand L1b. These results extend
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the range of substrates for which monodentate phosphoroamidite
ligands have proven to be promising and therefore open up new
lines of research on the use of monophosphoroamidites for the
asymmetric hydroformylation of more challenging substrates such
as heterocyclic olefins.
van Leeuwen, P. W. N. M., Claver, C., Eds.; Kluwer Academic Press: Dordrecht,
2000; (e) Claver, C.; Pàmies, O.; Diéguez, M.. In Phosphorous Ligands in
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3. See for example: (a) Axtell, A. T.; Cobley, C. J.; Klosin, J.; Whiteker, G. T.; Zanotti-
Gerosa, A.; Abboud, K. A. Angew. Chem., Int. Ed. 2005, 44, 5834; (b) Huang, J.;
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4
4
. Experimental section
4.
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J. Am. Chem. Soc. 2005, 127, 5040; (b) Thomas, P. J.; Axtell, A. T.; Klosin, J.; Peng,
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.1. General considerations
(
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All experiments were carried out under an argon atmosphere.
All solvents were dried using standard methods and distilled prior
5
.
1
7
to use. Ligands were prepared by previously described methods.
6. See for instance. (a) Reetz, M. T.; Mehler, G. Angew. Chem., Int. Ed. 2000, 39,
889; (b) Peña, D.; Minnaard, A. J.; Boogers, J. A.; de Vries, A. H. M.; de Vries, J.
3
Commercial substrates S1–S8 were used without further purifica-
tion. cis-2,2-Dimethyl-4,7-dihydro-1,3-dioxepin S9 was prepared
according to the method described in the literature.18
G.; Feringa, B. L. Org. Biomol. Chem. 2003, 1, 1087.
7
.
.
See for instance: (a) Biswas, K.; Prieto, O.; Goldsmith, P. J.; Woodward, S. Angew.
Chem., Int. Ed. 2005, 44, 2232; (b) Mata, Y.; Diéguez, M.; Pàmies, O.; Woodward,
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A.; Vuagnoux-d’Augustin, M.; Rosset, S.; Bernardinelli, G.; Alexakis, A. Angew.
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Alexakis, A.; Bäckvall, J. E.; Krause, N.; Pàmies, O.; Diéguez, M. Chem. Rev. 2008,
8
4
.2. Typical hydroformylation procedure for vinylarenes S1–S5
In a typical experiment, the autoclave was purged three times
with CO. The solution was formed from [Rh(acac)(CO)
2
] (3.1 mg,
1
08, 2796.
0
.0125 mmol) and ligand (0.025 mmol) in toluene (10 mL). After
9
.
Hua, Z.; Vassar, V. C.; Choi, H.; Ojima, I. PNAS 2004, 101, 5411.
pressurizing to the desired pressure with syngas and heating the
autoclave to the reaction temperature, the reaction mixture was
stirred for 16 h to form the active catalyst. The autoclave was
depressurized and a solution of substrate (6.25 mmol) in toluene
10. It should be pointed out that related monophosphite ligands provided lower
enantioselectivities (up to 43%) in the Rh-catalyzed hydroformylation of allyl
cyanide. See: (a) Cobley, C. J.; Klosin, J.; Qin, C.; Whiteker, G. T. Org. Lett. 2004, 6,
3277; (b) Cobley, C. J.; Gardner, K.; Klosin, J.; Praquin, C.; Hill, C.; Whiteker, G.
T.; Zannotti-Gerosa, A.; Petersen, J. L.; Abboud, K. J. Org. Chem. 2004, 69, 4031.
1. See for example: (a) Reetz, M. T. Chim. Oggi 2003, 21, 5; (b) Minnaard, A. J.;
Feringa, B. L.; Lefort, L.; de Vries, J. G. Acc. Chem. Res. 2007, 40, 1267; (c)
Diéguez, M.; Pàmies, O.; Ruiz, A.; Claver, C. Phosphite Ligands in Asymmetric
Hydrogenation. In Methodologies in Asymmetric Catalysis; Malhotra, S. V., Ed.;
ACS: Washington, 2004; Vol. 880, p 161.
1
(
5 mL) was introduced into the autoclave, which was pressurized
again. During the reaction several samples were taken from the
autoclave. After the desired reaction time, the autoclave was
cooled to room temperature and depressurized. The reaction mix-
ture was analyzed by gas chromatography.19
12.
See for instance: (a) Lefort, L.; Boogers, J. A. F.; de Vries, A. H. M.; de Vries, J. G.
Org. Lett. 2004, 6, 1733; (b) Swennenhuis, B. H. G.; Chen, R.; van Leeuwen, P. W.
N. M.; de Vries, J. G.; Kamer, P. C. J. Org. Lett. 2008, 10, 989.
4
.3. Typical hydroformylation procedure for heterocyclic
13. See for instance: (a) Reetz, M. T.; Sell, T.; Meiswinkel, A.; Mehler, G. Angew.
Chem., Int. Ed. 2003, 42, 790; (b) Reetz, M. T.; Li, X. Angew. Chem., Int. Ed. 2005,
substrates S6–S9
4
4, 2962.
1
4. (a) See for instance: Vietti, D. E. U.S. Patent 43,76,208, 1983; (b) Hoiuchi, T.;
Ota, T.; Shirakawa, E.; Nozaki, K.; Takaya, H. J. Org. Chem 1997, 62, 4285; (c) del
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S. H.; Bellini, R.; Berthon-Gelloz, B.; van der Vlugt, J. I.; de Bruin, B.; Reek, J. N. H.
Chem. Commun. 2010, 46, 1244.
The autoclave was purged three times with carbon monoxide.
2
The solution of [Rh(acac)(CO) ] (3.1 mg, 0.0125 mmol), ligand
(
0.025 mmol) and substrate (5 mmol for S6 and S7 and 1.25 mmol
for S8 and S9) in toluene (5 mL) was transferred to the stainless-
steel autoclave. After pressurizing to 25 bar of syngas and heating
the autoclave to the desired temperature, the reaction mixture was
stirred for the time shown in Tables 4–6. Conversions and selectiv-
1
1
5. (a) Polo, A.; Real, J.; Claver, C.; Castillón, S.; Bayón, J. C. J. Chem. Soc., Chem.
Commun. 1990, 600; (b) Polo, A.; Claver, C.; Castillón, S.; Ruiz, A.; Bayón, J. C.;
Real, J.; Mealli, C.; Masi, D. Organometallics 1992, 11, 3525.
6. There are only two Rh-catalytic systems that have provided better
enantioselectivities. One modified with the phosphine–phosphite binaphos
ligand (ees up to 76% and 69% for S8 and S9, respectively, see Ref. 14b) and the
second modified with a furanoside diphosphite ligand (ees up to 68%, see Ref.
1
ities of the reaction were determined immediately by H NMR
analysis of the crude reaction mixture without evaporation of the
solvent. The enantiomeric excesses and absolute configurations
were determined using the procedures described in Ref. 14b.
14e).
1
7. For the preparation of L1–L4 see: Alexakis, A.; Polet, D.; Rosset, S.; March, S. J.
Acknowledgements
Org. Chem. 2004, 69, 5660; For L5–L7 see: Palais, L.; Alexakis, A. Chem. Eur. J.
2009, 15, 10473.
1
1
8. Elliott, W. J.; Fried, J. J. Org. Chem. 1976, 41, 2469.
9. (a) Diéguez, M.; Pàmies, O.; Ruiz, A.; Castillón, S.; Claver, C. Chem. Eur. J. 2001, 7,
We thank the Spanish Government (Consolider Ingenio
CSD2006-0003, 2008PGIR/07 to O.P. and 2008PGIR/08 and ICREA
Academia award to M.D.), the Catalan Government (2009SGR116),
3086; (b) Guimet, E.; Parada, J.; Ruiz, A.; Claver, C.; Diéguez, M. APCATA 2005,
282, 215.