Enantioselective palladium catalyzed allylic amination using new chiral pyridine-phosphine ligands

Article abstract of DOI:10.1055/s-1998-1561

Asymmetric palladium catalyzed allylic amination of 5 with various amines has been studied using a new class of chiral pyridine-phosphine ligands. High enantioselectivities of up to 94% ee have been observed using benzylamine, veratrylamine or morpholine

Full text of DOI:10.1055/s-1998-1561

January 1998
SYNLETT
49
Enantioselective Palladium Catalyzed Allylic Amination Using New Chiral
Pyridine-Phosphine Ligands
*
Thierry Constantieux, Jean-Michel Brunel, Agnès Labande, Gérard Buono
Ecole Nationale Supérieure de Synthèse, de Procédés et d’Ingénierie Chimiques d’Aix Marseille (E.N.S.S.P.I.C.A.M.), UMR 6516 CNRS, Av. Escadrille
Normandie Niemen, 13397 Marseille, Cedex 20, France
Fax : 04-91-02-77-76 ; E-mail : buono@spi-chim.u-3mrs.fr
Received 8 October 1997
Abstract
5
: Asymmetric palladium catalyzed allylic amination of with
various amines has been studied using a new class of chiral pyridine-
phosphine ligands. High enantioselectivities of up to 94% ee have been
observed using benzylamine, veratrylamine or morpholine as
nucleophiles.
In recent years, various C -symmetric and non symmetric chiral ligands
2
bearing phosphine(s), nitrogen(s) and/or sulfur(s) have been developed
1
and used in numerous transition metal catalyzed reactions such as
2
3
hydrogenations and allylic substitutions . Thus, a wide class of non
symmetric chiral PN-, SN- type ligands were efficiently used as ligands
for catalytic asymmetric reactions, on the basis of their electronic as
4,5
well as steric effects . In almost these cases, the phosphorus atom is
not stereogenic, the chirality being induced by a chiral oxazoline or
imidazoline group which have been recognized as effective parts
4b
inducing high enantioselectivity
.
Recently, we described the use of a new non symmetric chiral ligand
bearing the chirality at the phosphorus atom in a palladium catalyzed
6
asymmetric alkylation with enantioselectivities up to 87% . We report
1
the preparation of various analogues of chiral ligand
and their
7
application to the palladium catalyzed asymmetric allylic amination .
1-4
Diastereoselective synthesis of ligands
was accomplished by
toluene between
exchange reaction in refluxing
tris(dimethylamino)phosphine and (S)-2-anilinomethylpyrrolidine or
(S)-2-naphthylaminomethylpyrrolidine followed by addition of the
corresponding
hydroxypyridine
hydroxyquinoline,
.
hydroxymethylpyridine
or
8,9
Using benzylamine as test nucleophile, a dramatic solvent effect on the
conversion is observed. Thus, under various experimental conditions no
reaction occurred in THF. Diethylether (entry 1) and dichloromethane
5a
(entry 2) led respectively to 70% and 100% conversion of
with a
good enantiomeric excess (ee) (77 and 79% ee respectively).
Nevertheless, the best results were obtained using toluene as solvent. A
7
total conversion was observed and the desired product obtained with
an ee up to 93% (entry 6). Moreover, a significant effect of the
temperature has been noticed and the best results were obtained at -10°C
(entries 3-6). The effect of the ligand used has also been taken into
1
4
led to excellent results in terms of
account. Ligands
and
enantioselectivity at -10°C (93% ee) (entries 6 and 9). Nevertheless,
2
3
and led to the
under the best experimental conditions, ligands
desired product with lower ee and an incomplete conversion (entries 7
and 8). Even with 1 mol% of the palladium catalyst, the reaction
proceeded in high enantioselectivity (92% ee, entry 10) and the product
was isolated in 80% chemical yield. Excellent results have been also
obtained using veratrylamine (94% ee, entries 11 and 12) and
morpholine (88% ee, entry 13) as nucleophiles.
5a
Asymmetric allylic amination of 1,3-diphenyl-2-propenyl acetate
or
5b
1,3-diphenyl-2-propenyl carbonate
with primary or secondary
1-4
amines was carried out with palladium(II)-phosphines
catalysts (Table 1).
complex

50
LETTERS
SYNLETT
(6) Brunel, J. M.; Constantieux, T.; Labande, A.; Lubatti, F.; Buono, G.
It is generally well assumed that the enantioselective step in palladium
1997, , 5971.
38
Tetrahedron Lett.
catalyzed allylic amination is the substitution of π-allyl complexes with
nucleophiles, the nucleophilic attack occurring predominantly at the
(7) Various groups have already reported high ee in asymmetric
palladium catalyzed allylic amination, for example see : (a) Hayashi,
T.; Yamamoto, A.; Ito, Y.; Nishioka, E.; Miura, H.; Yanagi, K. J.
Am. Chem. Soc. 1989, 111, 6301. (b) Trost, B. M.; Van Vranken, D.
L. J. Am. Chem. Soc. 1993, 115, 444. (c) Togni, A.; Burkhardt, U.;
Gramlich, V.; Pregosin, P. S.; Salzmann, R. J. Am. Chem. Soc. 1996,
118, 1031. (d) Von Matt, P.; Loiseleur, O.; Koch, G.; Pfaltz, A.;
Lebefer, C.; Feucht, T.; Helmchen, G. Tetrahedron Asymmetry 1994,
5, 573.
4,10,11
alkyl terminus trans to the better π-acceptor (P>>N)
. Since the (S)
product was obtained as the major enantiomer the reaction probably
proceeds through an M-type.
(8) The reaction was monitored by 31P NMR spectroscopy and after 2 h,
the solvent was removed under vacuum. The product was purified by
column chromatography (eluent : AcOEt/petroleum ether) affording
the corresponding ligands 1-4 in good chemical yields and in a total
anti diastereoselectivity. Syn diastereomer could not be obtained due
to the highly unstable intermediate compound which totally
epimerizes at the phosphorus atom to produce the thermodynamic
diastereomer anti. (a) Cros, P.; Buono, G.; Peiffer, G.; Denis, D.;
Mortreux, A.; Petit, F. New. J. Chem. 1987, 11, 573.
(b) Arzoumanian, H.; Buono, G.; Choukrad, M’B.; Petrignani, J. F.
1988, , 59. (c) Brunel, J. M.; Chiodi, O.; Faure, B.;
Organometallics
7
This model proposes that trapping of the π-allyl species occurs opposite
to the phosphine, as its superior π-accepting properties makes C-1 of the
allylic acetate electron deficient. Therefore, based on this analysis, 8
Fotiadu, F.; Buono, G. J. Organomet. Chem. 1997, 529, 285. The
definitions of the syn and anti isomers are according to the position
of the pyrrolidine ring and the aryl group. If they are at the same side
of the five membered phosphorus-containing ring, we call it a syn
isomer; otherwise, it is an anti isomer.
rather than 9 would be the diastereomeric complex responsible for the
12
product
.
(9) 1 : White solid ; m.p. = 135°C ; [α]20D = -45.6 (c = 1, CH2Cl2) ; 1H
NMR δ (ppm, CDCl3) 1.52-2.27 (m, 4H), 3.38-3.64 (m, 2H), 3.81-
4.03 (m, 3H), 7.02-7.57 (m, 9H), 8.18-8.28 (dd, J = 16 Hz, 1H), 8.95-
9.05 (dd, J = 16 Hz, 1H) ; 13C δ (ppm, CDCl3) 26.5, 26.6, 31.9, 47.6,
48.2 (d, J = 13 Hz), 53.7, 62.5, 115.3 (d, J = 13 Hz), 119.4, 121.0,
121.7, 127.2, 128.9, 130.1, 135.7, 148.7 ; 31P δ (ppm, CDCl3) 128.6.
2 : White solid ; m.p. = 152°C ; [α]20 = -39.3 ( = 1, CH Cl ) ; 1H
In summary, we have demonstrated that palladium complexes derived
from new chiral pyridine-phosphine ligands are efficient catalysts for
allylic aminations leading to enantioselectivities up to 94% ee. Further
studies are under current investigation in order to use these new ligands
in other asymmetric reactions.
c
D
2
2
NMR δ (ppm, CDCl3) 1.51-2.12 (m, 4H), 3.29-3.42 (m, 2H), 3.74-
4.03 (m, 3H), 7.01-7.86 (m, 12H), 8.15-8.25 (dd, J = 16 Hz, 1H),
8.97-9.02 (dd, J = 16 Hz, 1H) ; 13C δ (ppm, CDCl3) 26.5, 26.6, 31.9,
47.6, 48.2 0 (d, J = 12 Hz), 53.7, 62.5, 115.3 (d, J = 13 Hz), 119.2,
121.2, 121.5, 121.7, 123.2, 124.8, 127.2, 128.9, 130.1, 135.7, 148.7 ;
31P δ (ppm, CDCl3) 138.0. 3 : Pale yellow oil ; [α]20D = -39.2 (c = 1,
CH2Cl2) ; 1H NMR δ (ppm, CDCl3) 1.77-1.99 (m, 5H), 3.12-3.46
(m, 3H), 3.80-4.30 (m, 1H), 6.76-7.34 (m, 9H) ; 13C δ (ppm, CDCl3)
26.4, 31.6, 46.4, 50.0 (d, J = 13 Hz), 53.8, 116.5, 116.7 (d, J = 14
Hz), 121.4, 121.8, 121.9, 124.9, 129.2, 129.5 ; 31P δ (ppm, CDCl3)
124.1. 4 : White solid ; [α]20D = -35.2 (c = 1, CH2Cl2) ; 1H NMR δ
(ppm, CDCl3) 1.77-1.89 (m, 5H), 3.15-3.46 (m, 3H), 3.80-4.52 (m,
3H), 6.76-7.34 (m, 9H) ; 13C δ (ppm, CDCl3) 26.4 (d, J = 3Hz),,
30.6, 40.5, 46.4, 49.5 (d, J = 13 Hz), 53.10 (d, J = 5 Hz), 116.5 (d, J =
14 Hz), 116.7, 119.4, 120.8, 120.9, 123.9, 129.2, 130.5 ; 31P δ (ppm,
CDCl3) 122.1.
References and Notes
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115. (c) Ojima, I. (Ed.) in Catalytic Asymmetric Synthesis ; VCH
Publishers, Inc.; New York, 1993. (d) Seyden-Penne, J. in Chiral
Auxiliaries and Ligands in Asymmetric Synthesis ; John Wiley &
Sons, Inc.; New York, 1995. (e) Togni, A.; Venanzi, L. M. Angew.
1994, , 497.
33
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Williams, J. M. J. Synlett 1996, 705. (c) Pfaltz, A. Acc. Chem. Res.
1993, , 329. (d) Hayashi, T. in
26
Ojima, I. (Ed.) ; VCH Publishers, Inc.; New York, 1993 pp. 325. (e)
Consiglio, G.; Waymouth, R. M. Chem. Rev. 1989, 89, 257.
;
Catalytic Asymmetric Synthesis
(10) Akermark, B.; Hansson, S.; Krakenberger, B.; Vitagliano, A.;
Zetterberg, K. Organometallics 1984, 3, 679. (b) Akermark, B.;
Krakenberger, B.; Hansson, S.; Vitagliano, A. Organometallics
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J.; Williams, J. M. J. J. Chem. Soc., Perkin Trans I 1994, 2065. (b)
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1987, , 620. (c) Peña-cabrera, E.; Norrby, P.; Sjögren, M.;
6
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8
1996, , 1597. (c) Langer, T.; Janssen, J.; Helmchem, G.
Asymmetry
7
(12) In the structure of diastereomeric complexes 8 and 9, the absolute
configuration at the phosphorus atom has been well established by
X-ray analysis structure of ligand 1. Brunel, J. M.; Constantieux, T.;
Buono, G. Unpublished results.
1996, , 1599. (d) Morimoto, T.; Tachibana,
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2