Yvette Mata et al.
COMMUNICATIONS
KOAc were added. The reaction mixture was stirred at room
temperature. After 30 min the reaction mixture was diluted
with Et2O (5 mL) and saturated aqueous NH4Cl (25 mL) was
added. The mixture was extracted with Et2O (3ꢀ10 mL) and
the extract dried over MgSO4. Conversion and enantiomeric
excess was determined by GC.
To determine the ee by HPLC (Chiralcel OJ, 13% 2-propanol/
hexane, flow 0.5 mL/min), a sample was filtered over silica us-
ing 10% Et2O/hexane mixture as the eluent.
Acknowledgements
Typical Procedure for Allylic Alkylation of rac-3-
Acetoxycycloheptene (S3) and rac-3-
Acetoxycyclohexene (S4)
A degassed solution of [PdCl(h3-C3H5)]2 (1.8 mg, 0.005 mmol)
and the phosphite-oxazoline 2 (0.009 mmol) in dichlorome-
thane (0.5 mL) was stirred. After 30 minutes the solution was
brought to the desired temperature and subsequently, a solu-
tion of racemic substrate (0.5 mmol) in dichloromethane
(1.5 mL) at the desired temperature, dimethyl malonate
This work was supported by the Spanish Ministerio de Educa-
´
cion, Cultura y Deporte (BQU2001-0656), the Spanish Minis-
terio de Ciencia y Tecnologia (Ramon y Cajal fellowship to
O. P.) and the Generalitat de Catalunya (Distinction to M. D.).
References and Notes
[1] For recent reviews, see: a) B. M. Trost, D. L. van Vrank-
en, Chem. Rev. 1996, 96, 395; b) M. Johannsen, K. A. Jor-
gensen, Chem. Rev. 1998, 98, 1689; c) A. Pfaltz, M. Laut-
ens, in: Comprehensive Asymmetric Catalysis, (eds.: E. N.
Jacobsen, A. Pfaltz, H. Yamamoto), Springer-Verlag:
Berlin, 1999, Vol. 2, Chapter 24; d) G. Helmchen, A.
Pfaltz, Acc. Chem. Res. 2000, 33, 336; e) B. M. Trost,
M. L. Crawley, Chem. Rev. 2003, 103, 2921.
(171 mL,
1.5 mmol),
N,O-bis(trimethylsilyl)-acetamide
(370 mL, 1.5 mmol) and a pinch of KOAc were added. The re-
action mixture was stirred at the desired temperature. After 24
hours the reaction mixture was diluted with Et2O (5 mL) and
saturated aqueous NH4Cl (25 mL) was added. The mixture
was extracted with Et2O (3ꢀ10 mL) and the extract dried
over MgSO4. Conversion was determined by GC. For substrate
S3, to determine the ee by 1H NMR (using Eu(hfc)3 as resolving
reagent), a sample was purified on silica using an Et2O/hexane
(1/4) mixture as the eluent. For substrate S4, the enantiomeric
excess was determined by GC.
´
´
´
[2] A. M. Masdeu-Bulto, M. Dieguez, E. Martin, M. Gomez,
Coord. Chem. Rev. 2003, 242, 159.
´
`
[3] a) M. Dieguez, O. Pamies, C. Claver, Chem. Rev. 2004,
´
`
104, 3189; b) M. Dieguez, O. Pamies, A. Ruiz, Y. Díaz,
´
S. Castillon, C. Claver, Coord. Chem. Rev. 2004, 248,
´
2165; c) M. Dieguez, A. Ruiz, C. Claver, Dalton Trans.,
2003, 2957.
Typical Procedure for Allylic Alkylation of rac-1-(1-
Naphthyl)allyl Acetate (S5)
[4] a) B. Gläser, H. Kunz, Synlett 1998, 53; b) K. Yonehara,
T. Hashizume, K. Mori, K. Ohe, S. Uemura, Chem. Com-
mun. 1999, 415; c) K. Yonehara, T. Hashizume, K. Mori,
K. Ohe, S. Uemura, J. Org. Chem. 1999, 64, 9374.
[5] Bulky biphenyl phosphites are known to provide larger
bite angles than phosphinites. The opening of the bite an-
gle is necessary for high chiral recognition in the Pd-cat-
alyzed alkylation reactions: a) B. M. Trost, D. L. van V-
ranken, C. Bingel, J. Am. Chem. Soc. 1992, 114, 9327;
b) P. W. N. M. van Leeuwen, P. C. J. Kamer, J. N. H.
Reek, P. Dierkes, Chem. Rev. 2000, 100, 2741.
[6] The flexibility offered by the biphenyl moiety can be
used to fine-tune the chiral pocket formed upon com-
plexation.
[7] To date, phosphite ligands have proven to be highly ver-
satile in Pd-catalyzed asymmetric substitution reactions,
A degassed solution of [PdCl(h3-C3H5)]2 (3.6 mg, 0.01 mmol)
and the phosphite-oxazoline 5 (0.018 mmol) in dichlorome-
thane (0.5 mL) was stirred for 30 min at room temperature.
Subsequently, a solution of rac-1-(1-naphthyl)allyl acetate
(0.5 mmol) in dichloromethane (1.5 mL), dimethyl malonate
(171 mL,
1.5 mmol),
N,O-bis(trimethylsilyl)-acetamide
(370 mL, 1.5 mmol) and a pinch of KOAc were added. After
2 hours the reaction mixture was diluted with Et2O (5 mL)
and saturated aqueous NH4Cl (25 mL) was added. The mixture
was extracted with Et2O (3ꢀ10 mL) and the extract dried over
MgSO4. Solvent was removed and conversion and regioselec-
1
tivity were measured by H NMR. To determine the ee by
HPLC (Chiralcel OJ, 13% 2-propanol/hexane, flow 0.7 mL/
min), a sample was filtered over basic alumina using dichloro-
methane as the eluent.
´
`
see, for example: a) M. Dieguez, O. Pamies, C. Claver,
Typical Procedure for Allylic Amination of rac-1,3-
`
´
J. Org. Chem. 2005, 70, 3363; b) O. Pamies, M. Dieguez,
Diphenyl-3-acetoxyprop-1-ene (S1)
´
C. Claver, J. Am. Chem. Soc. 2005, 127, 3646; c) M. Die-
`
guez, O. Pamies, C. Claver, Adv. Synth. Catal. in press.
A degassed solution of [PdCl(h3-C3H5)]2 (3.6 mg, 0.01 mmol)
and the phosphite-oxazoline 2 (0.018 mmol) in dichlorome-
thane (0.5 mL) was stirred for 30 min. Subsequently, a solution
of S1 (126 mg, 0.5 mmol) in dichloromethane (1.5 mL) and
benzylamine (131 mL, 1.5 mmol) were added. The reaction
mixture was stirred at room temperature. After 24 hours the re-
action mixture was diluted with Et2O (5 mL) and saturated
aqueous NH4Cl (25 mL) was added. The mixture was extracted
with Et2O (3ꢀ10 mL) and the extract dried over MgSO4. Sol-
vent was removed and conversion was measured by 1H NMR.
[8] Phosphorochloridites are easily prepared in one step
from the corresponding bisphenol as described in:
G. J. H. Buisman, P. C. J. Kamer, P. W. N. M. van Leeu-
wen, Tetrahedron: Asymmetry 1993, 4, 1625.
[9] This behavior is in contrast with the phosphite-substitu-
ent effect observed for other phosphite ligands, for which
enantioselectivities were highly affected by the substitu-
ents at the ortho positions of the biphenyl moieties, see
ref.[7]
1946
asc.wiley-vch.de
ꢀ 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2005, 347, 1943 – 1947