Palladium-catalyzed amination of aryl bromides utilizing arene-chromium complexes as ligands

Article abstract of DOI:10.1021/jo981327+

The arene - chromium complexes of o-diphenylphosphino α- phenylethylamine or α-phenylethyl methyl ether derivatives were examined with regard to their activity as ligands for palladium(0)-catalyzed aryl amination of aryl bromides with a variety of amines. Both steric and electronic factors were found to be significant for the efficient palladium- catalyzed aryl amination reactions. Modulation of the inductive capacity of the arylphosphine atom was achieved by photoinduced ligand exchange of one carbonyl of the chromium tripode in the presence of electron-donating triphenylphosphine or phosphite. Among these arene - chromium ligands, the use of the monophosphineor monophosphite-(dicarbonyl)chromium of N,N- dimethyl α-(o-diphenylphosphino)phenylethylamine and methyl α-(o- diphenylphosphino)phenylethyl ether produced the palladium(0)-catalyzed aryl amination products with cyclic amines or acyclic secondary amines in high yields; the corresponding strong electron-withdrawing tricarbonylchromium complex resulted in a modest yield of the aryl amination.

Full text of DOI:10.1021/jo981327+

J . Org. Chem. 1998, 63, 8407-8410
8407
P a lla d iu m -Ca ta lyzed Am in a tion of Ar yl Br om id es Utilizin g
Ar en e-Ch r om iu m Com p lexes a s Liga n d s
Ken Kamikawa,†,‡ Suguru Sugimoto,‡ and Motokazu Uemura*,‡,§
Department of Chemistry, Faculty of Integrated Arts and Sciences, Osaka Prefecture University, Sakai,
Osaka 599-8531 J apan, and Research Institute for Advanced Science and Technology, Osaka Prefecture
University, Sakai, Osaka 599-8570, J apan
Received J uly 8, 1998
The arene-chromium complexes of o-diphenylphosphino R-phenylethylamine or R-phenylethyl
methyl ether derivatives were examined with regard to their activity as ligands for palladium(0)-
catalyzed aryl amination of aryl bromides with a variety of amines. Both steric and electronic
factors were found to be significant for the efficient palladium-catalyzed aryl amination reactions.
Modulation of the inductive capacity of the arylphosphine atom was achieved by photoinduced ligand
exchange of one carbonyl of the chromium tripode in the presence of electron-donating triphen-
ylphosphine or phosphite. Among these arene-chromium ligands, the use of the monophosphine-
or monophosphite-(dicarbonyl)chromium of N,N-dimethyl R-(o-diphenylphosphino)phenylethylamine
and methyl R-(o-diphenylphosphino)phenylethyl ether produced the palladium(0)-catalyzed aryl
amination products with cyclic amines or acyclic secondary amines in high yields; the corresponding
strong electron-withdrawing tricarbonylchromium complex resulted in a modest yield of the aryl
amination.
In tr od u ction
ligands PPFA and PPF-OMe have been also employed
for the palladium(0)-catalyzed coupling of acyclic second-
ary amines with bromobenzene.4 Toward further devel-
opment of the palladium-catalyzed aryl aminations, we
have explored the reactivity of different ligands and
studied the effect of their structures on the outcome of
amine coupling. For this purpose, we chose to use
chromium-complexed chelating arene ligands due to their
easy preparation and availability for further structural
modification. Furthermore, these arene-chromium com-
plexes would be expected to be useful as the chiral ligands
for palladium-catalyzed asymmetric reactions. Herein,
we wish to report that the palladium complexes derived
from chromium-complexed arenes possessing diphen-
ylphosphine on the ring and a dimethylamine or meth-
oxyl group at the benzylic position are highly effective
for the aryl amination reaction with both acyclic and
cyclic secondary amines.
The recent development in the palladium-catalyzed
amination of aryl halides or triflates documented by
Buchwald and Hartwig, independently, has been shown
to be a general method for the formation of aromatic
carbon-nitrogen bonds.1 The mild conditions in the
palladium-catalyzed aryl amination offer considerable
advantages over the classical methods, which require
either activated molecules or severe reaction conditions.
In the palladium-catalyzed aryl amination, the stereo and
electronic effects of the employed palladium ligands and
the bite angle of the chelating ligands are significant
factors for efficient coupling reactions.2 In general terms,
modestly hindered and electron-rich aryl phosphine
ligands have been used for efficient palladium(0)-
catalyzed aryl amination reactions. Thus, the mono-
phosphine ligand P(o-tolyl)3 or bisphosphine ligands
BINAP and DPPF lead to efficient coupling of various
amines with aryl bromides.1,3 The ferrocenyl derived
Resu lts a n d Discu ssion
† Research Fellow of the J apan Society for the Promotion of Science.
‡ Faculty of Integrated Arts and Sciences, Osaka Prefecture Uni-
versity.
While arene-chromium complexes have been widely
employed for stoichiometrically asymmetric reactions
based on the characteristic properties of electron-
withdrawing ability and the steric bulkiness of the
tricarbonylchromium fragment,5 there have been few
§ Research Institute for Advanced Science and Technology, Osaka
Prefecture University.
(1) For representative review and references see: (a) Hartwig, J .
F. Synlett 1997, 329-340. (b) Wolfe, J . P.; Buchwald, S. L. J . Org.
Chem. 1997, 62, 1264-1267. (c) Louie, J . L.; Driver, M. S.; Hamann,
B. C.; Hartwig, J . F. J . Org. Chem. 1997, 62, 1268-1273. (d) Driver,
M. S.; Hartwig, J . F. J . Am. Chem. Soc. 1996, 118, 7217-7218. (e)
Wolfe, J . P.; Wagaw, S.; Buchwald, S. L. J . Am. Chem. Soc. 1996, 118,
7215-7216. (f) Guram, S.; Rennels, R. A.; Buchwald, S. L. Angew.
Chem., Int. Ed. Engl. 1995, 34, 1348-1350.
(4) (a) Marcoux, J .-F.; Wagaw, S.; Buchwald, S. L. J . Org. Chem.
1997, 62, 1568-1569. (b) Wolfe, J . P.; Buchwald, S. L. Tetrahedron
Lett. 1997, 38, 6359-6362.
(5) For some reviews see: (a) Collman, J . P.; Hegedus, L. S.; Norton,
J . R.; Finke, R. G. Principles and Applications of Organotransition
Metal Chemistry; University Science Books: Mill Valley, CA, 1987;
pp 922-940. (b) Solladie´-Cavallo, A. In Advances in Metal-Organic
Chemistry; Liebeskind, L. S., Ed.; J AI Press: Greenwich, CT, 1989;
Vol. 1, pp 99-133. (c) Davies, S. G.; Coote, S. J .; Goodfellow, C. L. In
Advances in Metal-Organic Chemistry; Liebeskind, L. S., Ed.; J AI
Press: Greenwich, CT, 1991; Vol. 2, pp 1-57. (d) Uemura, M. In
Advances in Metal-Organic Chemistry; Liebeskind, L. S., Ed.; J AI
Press: Greenwich, CT, 1991; Vol. 2, pp 195-245.
(2) Hamann, B. C.; Hartwig, J . F. J . Am. Chem. Soc. 1998, 120,
3694-3703.
(3) Some representative references include the following: (a) Guram,
A. S.; Buchwald, S. L. J . Am. Chem. Soc. 1994, 116, 7901-7902. (b)
Hartwig, J . F.; Paul, F. J . Am. Chem. Soc. 1995, 117, 5373-5374. (c)
Wagaw, S.; Rennels, R. A.; Buchwald, S. L. J . Am. Chem. Soc. 1997,
119, 8451-8458. (d) Singer, R. A.; Sadighi, J . P.; Buchwald, S. L. J .
Am. Chem. Soc. 1998, 120, 213-214. (e) Mann, G.; Hartwig, J . F.;
Driver, M. S.; Ferna´ndez-Rivas, C. J . Am. Chem. Soc. 1998, 120, 827-
828.
(6) Uemura, M.; Miyake, R.; Nakayama, K.; Shiro, M.; Hayashi, Y.
J . Org. Chem. 1993, 58, 1238-1244.
10.1021/jo981327+ CCC: $15.00 © 1998 American Chemical Society
Published on Web 10/21/1998

8408 J . Org. Chem., Vol. 63, No. 23, 1998
Kamikawa et al.
Ta ble 1. Liga n d Effect for P a lla d iu m (0)-Ca ta lyzed
Am in a tion of 4-Br om otolu en e w ith P ip er id in e
ligand
yield 13 (%)
ligand
yield 13 (%)
1
2
3
4
5
6
41
49
72
62
68
34
7
8
9
10
11
12
23
48
65
57
34
40
produced a chelated dicarbonyl(diphenylphosphine)-
chromium complex 12 even in the presence of triphen-
ylphosphine, and the structure was determined by X-ray
analysis.15
F igu r e 1. Arene ligands for palladium(0)-catalyzed aryl
amination.
examples of their use as the ligand of catalytic reactions6-11
compared with the number for ferrocenyl compounds. The
electronic and steric tuning of the arene-chromium
complexes could be easily modified by the introduction
of an appropriate functional group on the arene ring or
side chain or ligand exchange of the chromium tripode.
With the objective of expanding this emerging class of
new catalysts, we became interested in exploiting the
electronic properties of arene-chromium carbonyl com-
plexes, especially the ability to tune electronic param-
eters of the arene by selection of appropriate tripod
ligands.12 Modulation of the electronic parameters via
ligand substitution of the chromium tripode would be a
key feature for controlling the electron density of an aryl
phosphine group. The chromium and chromium-free
arene ligands employed in this palladium-catalyzed aryl
amination are shown in Figure 1, and the tricarbonyl-
chromium ligands 2 and 7 were easily prepared by
regioselective lithiation of tricarbonylchromium-com-
plexed N,N-dimethyl R-phenylethylamine and R-phenyl-
ethyl methoxymethyl ether followed by quenching with
chlorodiphenylphosphine in a racemic or an enantiomeri-
cally active form.13,14 Tricarbonylchromium-complexed
bisdiphenylphosphino compound 11 was prepared by the
previously reported procedure.8 The corresponding di-
carbonyl-monophosphines or -monophosphite complexes,
3, 4, 5, 8, 9, and 10, were prepared from 2 and 7 by a
photolytic ligand exchange reaction in the presence of the
corresponding phosphine or phosphite reagent.6,7 How-
ever, photolysis of the bisdiphenylphosphino complex 11
We initially examined the ability of the chromium-
complexed arene ligands for the palladium(0)-catalyzed
coupling of aryl bromide with a cyclic amine (Table 1).
The reaction optimization was conducted on 4-bromo-
toluene and piperidine in the presence of 1.5 equiv of
NaOtBu and a combination of 1.0 mol % of Pd(dba)2 and
3.0 mol % of the arene ligand in toluene at 100 °C for 5
h. Use of optically pure (-)-tricarbonyl[N,N-dimethyl
R-(o-diphenylphosphinophenyl)ethylamine]chromium (2)
as the ligand resulted in 49% yield of N-(p-methylphenyl)-
piperidine. The corresponding chromium-free amino-
phosphine ligand 1 gave a moderate 41% yield of the
coupling product. However, an electron-donating mono-
phosphine or monophosphite dicarbonyl chromium com-
plex instead of tricarbonylchromium ligands increased
the yield of the amination product remarkably under
same conditions. Thus, (-)-monotriphenylphosphine-
(dicarbonyl)chromium, (-)-monotrimethyl phosphite(di-
carbonyl)chromium, and (-)-monotriphenyl phosphite-
(dicarbonyl)chromium complexes of aminophosphine
ligands 3, 4, and 5 produced the coupling product in 72,
62, and 68% yields, respectively. These results showed
that both steric and electronic factors of the arene
chromiun ligands are significant for efficient palladium-
catalyzed aryl amination reactions. While the electron
density of the aryl phosphine atom of the ligand 2 was
reduced due to the strong electron-withdrawing ability
of the tricarbonylchromium fragment, the corresponding
monophosphine or monophosphite dicarbonyl chromium
ligands 3, 4, and 5 became more electron rich. It is
interesting that these chromium complexes ligands are
effective for the palladium-catalyzed aryl aminations
despite the large difference in the bite angle of P-Pd-
N(or O) of chromium-complexed palladium catalysts
compared with those of the ferrocenyl ligands, PPF or
PPF-OMe.2,16 Also, the presence of the corresponding
benzylic oxygen analogues instead of the nitrogen atom
indicated a similar behavior for the palladium-catalyzed
amination. Thus, use of the racemic tricarbonyl[methyl
R-(o-diphenylphosphino)phenylethyl ether]chromium (7)
gave the amination product in only 23% yield, while the
corresponding electron-donating ligands 8, 9, and 10
increased the amination product to 48%, 65%, and 57%
yields, respectively. These data demonstrate that the
(7) Uemura, M.; Miyake, R.; Nishimura, H. Tetrahedron Asymmetry
1992, 3, 213-216.
(8) Hayashi, Y.; Sakai, H.; Kaneta, N.; Uemura, M. J . Orgmet. Chem.
1995, 503, 143-148.
(9) J ones, G. B.; Heaton, S. B. Tetrahedron Lett. 1992, 33, 1693-
1696.
(10) J ones, G. B.; Heaton, S. B. Tetrahedron Asymmetry 1993, 4,
261-272.
(11) J ones, G. B.; Heaton, S. B.; Chapman, B. J .; Guzel, M.
Tetrahedron Asymmetry 1997, 8, 3625-3635.
(12) J ones, G. G.; Chapman, B. J .; Mathews, J . E. J . Org. Chem.
1998, 63, 2928-2938.
(13) (a) Heppert, J . A.; Thomas-Miller, M. E.; Milligan, M. L.; Velde,
D. V.; Aube´, J . Organometallics 1988, 7, 2581-2584. (b) Heppert, J .
A.; Aube´, J .; Thomas-Miller, M. E.; Milligan, M. L.; Takusagawa, F.
Organometallics 1990, 9, 727-739.
(14) Blagg, J .; Davies, S. G.; Goodfellow, C. L.; Sutton, K. H. J .
Chem. Soc., Perkin Trans. 1 1987, 1805-1811.
(15) Crystal structure data: formula, C34H28O2P2Cr; fw; 582.54;
triclinic; space group P1 (no. 1); a ) 9.031(3) Å; b ) 10.489(3) Å; c )
8.551(4) Å; R ) 98.96(3)°; â ) 112.44(3)°; γ ) 83.67(3)°; V ) 738.4(5)
Å3; Z ) 1; Dcalc ) 1.310 g cm-3; final R ) 0.037; Rw ) 0.044.

Palladium-Catalyzed Amination of Aryl Bromides
J . Org. Chem., Vol. 63, No. 23, 1998 8409
Ta ble 2. P a lla d iu m (0)-Ca ta lyzed Am in a tion of Ar yl
Br om id es w ith Cyclic Am in es by a Com bin a tion of
P d (d ba )2 a n d Liga n d 3a
Ta ble 3. P a lla iu m (0)-Ca ta lyzed Am in a tion of Ar yl
Br om id es w ith Acyclic Am in es by a Com bin a tion of
P d (d ba )2 a n d (Ar en e)ch r om iu m Liga n d
a
Reactions were conducted with 1.0 mol % Pd(dba)2, 3.0 mol %
ligand 3, and 1.5 equiv of NaOBut in toluene at 100 °C for 5 h.
chromium complexation of amino phosphine ligands is
essential to achieving high yield of the amination product
and the exchange of one of the three carbonyls on the
chromium fragment to the electron-donating phosphine
or phosphite could be a more significant factor for the
efficient palladium-catalyzed aryl aminations. Also, the
monophosphine or monophosphite(dicarbonyl)chromium
complexes of amino phosphine ligands 3, 4, and 5 showed
slightly higher activity than the corresponding benzyl
oxygen analogues 8, 9, and 10 for the palladium-
catalyzed amination reaction. The tricarbonylchromium
complex of bisphosphine compound 11 and the chelated
monodentate diphenylphosphine(dicarbonyl)chromium
complex 12 gave a modest yield of the amination product
of p-bromotoluene with piperidine.17
We next studied the palladium-catalyzed amination of
both electron-poor and electron-rich aryl bromides with
other cyclic amines using arene-chromium complexes as
the ligand. The amination of aryl bromides with cyclic
amines was carried out under identical reaction condi-
tions by a combination of 1.0 mol % of Pd(dba)2 and 3.0
mol % of the arene ligand 3 in the presence of NaOtBu
in toluene (Table 2). These results demonstrate that the
electron-poor aryl bromides gave the palladium-catalyzed
amination products with cyclic amines in good yields, and
the yield in the amination of the electron-rich arene was
slightly decreased under the same reaction conditions.
These monophosphine(dicarbonyl)chromium complexed-
arene compounds were found to be also effective ligands
for palladium-catalyzed amination of aryl bromides with
acyclic secondary amines (Table 3). Thus, both electron-
poor and electron-rich aryl bromides produced the ami-
nation products with acyclic dialkylamines or aryl alkyl-
amines in good yields. With electron-rich arenes, the
monotriphenylphosphine(dicarbonyl)chromium of di-
methylamino phosphine ligand 3 showed higher activity
than the corresponding ether ligand 9 (entries 1 vs 2 and
5 vs 6). With the electron-poor aryl bromides, both
chromium-complexed ligands possessing the dimethyl-
(16) For discussion about the bite angle that influences the rate of
reductive elimination of a transition-metal complex, see ref 3 and the
following: Collman, J . P.; Hegedus, L. S.; Norton, J . R.; Finke, R. G.
Principles and Applications of Organotransition Metal Chemistry;
University Science Books: Mill Valley, CA, 1987; pp 324-329.
(17) Surprisingly, the chelated monodentate ligand 12 produced the
corresponding amine compound for the coupling reaction of p-benzoyl
bromobenzene with morpholine in 88% yield.

8410 J . Org. Chem., Vol. 63, No. 23, 1998
Kamikawa et al.
Hz), 7.26-7.48 (25 H, m); IR (CHCl3) 1890, 1840 cm-1. Anal.
Calcd for C41H36O3P2Cr: C, 71.30; H, 5.27. Found; C, 71.11;
H, 5.19.
amino or methoxy groups at the benzylic position, 3, 8,
or 9, resulted in a high yield of the amination products.
It is noteworthy that this catalyst system of 3 and Pd-
(dba)2 was also effective for the preparation of triaryl-
amine by cross-coupling of aryl bromide with diarylamine
(entry 18).18 Bromopyridine was also coupled with di-
ethylamine to produce R-diethylaminopyridine in 57%
yield by using the amino ligand 3 (entry 19).
In conclusion, we have demonstrated that the arene-
chromium complex is able to modulate the inductive
capacity of the arylphosphine atom by substitution of the
chromium tripode and regulate its ability as a ligand for
the palladium-catalyzed aryl amination. Thus, the mono-
triphenylphosphine(dicarbonyl)chromium complex of N,N-
dimethyl R-(o-diphenylphosphino)phenylethylamine 3
was found to be an efficient supporting ligand for the
palladium-catalyzed amination of both electron-rich and
-deficient aryl bromides with cyclic or acyclic secondary
amines. We are currently investigating the scope of
palladium-catalyzed aryl amination by the electronic
modification of diarylphosphine, the application for asym-
metric reaction using the optically active arene-chro-
mium complexes as chiral ligands, and further extension
of the reaction to the coupling of aryl bromides with
ketone or alcohol compounds using the chromium-com-
plexed arene ligands.
(()-Ch ela ted Com p lex 12 (70% yield ): mp 110 °C; 1H
NMR (270 MHz, CDCl3) δ 1.53 (3 H, dd, J ) 7.9, 12.0 Hz) 3.84
(1 H, q, J ) 7.9 Hz), 4.05 (1 H, t, J ) 6.3 Hz), 4.82 (1 H, d, J
) 6.3 Hz), 5.03 (1 H, d, J ) 6.3 Hz), 5.51 (1 H, t, J ) 6.3 Hz),
7.19-7.52 (18 H, m), 7.91-7.99 (2 H, m); 31P NMR (162 MHz),
δ -8.6 (s), 20.2 (s); IR (CHCl3) 1970, 1900, 1840 cm-1. Anal.
Calcd for C34H28O2P2Cr: C, 70.04; H, 4.85. Found; C, 69.67;
H, 4.88.
P a lla d iu m -Ca ta lyzed Ar yl Am in a tion . Typical proce-
dure for the aryl amination is as follows. An oven-dried
Schlenk tube was charged with p-bromotoluene (171 mg, 1.0
mmol), piperidine (128 mg, 1.50 mmol), NaOtBu (144 mg, 1.50
mmol), Pd2(dba)3 (10.0 mg, 0.01 mmol), and the arene-
chromium ligand 3 (21 mg, 0.03 mmol) and purged with argon.
Toluene (2.50 mL) was added, and the reaction mixture was
heated at 100 °C under argon for 5 h. The reaction mixture
was filtered, and the filtrate was concentrated under reduced
pressure. The crude product was purified by chromatography
on silica gel with hexane/ethyl acetate (50/1) to give 127 mg
(72%) of N-(p-methylphenyl)piperidine1c as a liquid: 1H NMR
(CDCl3, 270 MHz) δ 1.56-1.73 (6 H, m), 2.27 (3 H, s), 3.09 (4
H, t, J ) 5.6 Hz), 6.87 (2 H, d, J ) 8.5 Hz), 7.06 (2 H, d, J )
8.5 Hz).
N-Eth yl-N-(p-tr iflu or om eth ylp h en yl)a n ilin e, a s a Liq-
1
u id : H NMR (CDCl3, 270 MHz) δ 1.23 (3 H, t, J ) 7.3 Hz),
3.78 (2 H, q, J ) 7.3 Hz), 6.77 (2 H, d, J ) 8.9 Hz), 7.15-7.23
(3 H, m), 7.35-7.41 (4 H, m); IR (CHCl3) 1580, 1480, 1310
cm-1; MS (relative intensity) m/z 265 (M+, 83), 250 (100), 237
(41), 198 (66); HRMS calcd for C15H14NF3 265.1079, found
265.1087.
Exp er im en ta l Section
N-Eth yl-N-(p-m eth ylp h en yl)a n ilin e: 1H NMR (CDCl3,
270 MHz) δ 1.20 (3 H, t, J ) 6.9 Hz), 2.32 (3 H, s), 3.74 (2 H,
All reactions were carried out under an argon atmosphere.
The tricarbonyl(o-diphenylphosphino arene)chromium ligands
were prepared by trapping an intermediate o-lithiated complex
of tricarbonyl(N,N-dimethyl R-phenylethylamine)chromium or
tricarbonyl(methoxymethyl R-phenylethyl ether)chromium with
chlorodiphenylphosphine according to the literature.13,14 The
ligand exchange of one carbonyl of the tricarbonyl fragment
to the corresponding phosphine or phosphite ligand was
achieved by irradiation with a high-pressure mercury lamp
in the presence of the corresponding phosphine or phosphite
reagents. Toluene was continuously refluxed and distilled
from calcium hydride. Aryl bromides were purchased from
commercial sources and were used without further purifica-
tion.
q, J ) 6.9 Hz), 6.82-7.23 (9 H, m); IR (CHCl3) 1580, 1480 cm-1
;
MS (relative intensity) m/z 211 (M+, 66), 196 (100), 167 (14),
113 (21).
N,N-Dieth yl-p-tr iflu or om eth yla n ilin e: 1H NMR (CDCl3,
270 MHz) δ 1.17 (6 H, t, J ) 6.9 Hz), 3.38 (4 H, q, J ) 6.9 Hz),
6.65 (2 H, d, J ) 8.9 Hz), 7.41 (2 H, d, J ) 8.9 Hz); IR (CHCl3)
1520, 1310, 1260, 1110 cm-1; MS (relative intensity) m/z 217
(M+, 66), 202 (35), 187 (35), 174 (100); HRMS calcd for C11H14
NF3 217.1078, found 217.1063.
-
N-Eth yl-N-(p-t-bu tylp h en yl)cycloh exyla m in e: 1H NMR
(CDCl3, 270 MHz) δ 1.15 (6 H, t, J ) 6.9 Hz), 1.28 (9 H, s),
1.31-1.85 (10 H, m), 3.25 (4 H, q, J ) 6.9 Hz), 3.50-3.51 (1
H, m), 6.67 (2 H, d, J ) 8.9 Hz), 7.23 (2 H, d, J ) 8.9 Hz); IR
(CHCl3) 1600, 1500 cm-1; MS (relative intensity) m/z 259 (M+,
45), 230 (2), 216 (100), 202 (3), 176 (5).
(-)-Tr iph en ylph osph in e(dicar bon yl)[N,N-dim eth yl r-(o-
d ip h en ylp h osp h in op h en yl)eth yla m in e]ch r om iu m (3).7
Typical procedure of ligand exchange of one of the three
carbonyls on the chromium in the presence of a phosphine or
N-(p-Ben zoylp h en yl)-N-m eth yla n ilin e: 1H NMR (CDCl3,
270 MHz) δ 3.38 (3 H, s), 6.78 (2 H, d, J ) 8.9 Hz), 7.22-7.75
(12 H, m); IR (CHCl3) 1630, 1580, 1490 cm-1; MS (relative
intensity) m/z 287 (M+, 85), 273 (4), 210 (100), 196 (4), 181
(10); MS (relative intensity) m/z 301 (M+, 63), 286 (100), 224
(5); HRMS calcd for C20H17NO 287.1310, found 287.1307.
phosphite reagent under photoirradiation is as follows.
A
solution of (-)-tricarbonyl[N,N-dimethyl R-(o-diphenylphos-
phinophenyl)ethylamine]chromium (2.0 g, 4.3 mmol) and
triphenylphosphine (2.0 g, 8.5 mmol) in benzene (30 mL) was
irradiated with a high-pressure mercury lamp under nitrogen
at room temperature for 20 min. The precipitate was filtered
off, and the filtrate was evaporated in vacuo. The residue was
purified by silica gel column chromatography with hexane/
Ack n ow led gm en t. This research was supported by
a Grant-in-Aid for Scientific Research from The Ministry
of Education, Science, Sports and Culture of J apan.
M.U. thanks The Asahi Glass Foundation and Chiba-
Geigy Foundation (for J apan) for financial support.
ethyl acetate (10/1) to give 2.0 g (63%) of 3: mp 151 °C; [R]22
D
-344 (c 0.58, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.85 (3 H,
d, J ) 7.0 Hz), 1.65 (6 H, s), 3.79 (1 H, m), 4.45-4.70 (4 H, m),
7.25-7.50 (25 H, m); IR (CHCl3) 1970, 1890 cm-1. Anal. Calcd
for C42H39O2NP2Cr: C, 71.69; H, 5.30; N, 1.99. Found; C,
71.42; H, 5.30; N, 2.10.
Su p p or t in g In for m a t ion Ava ila b le: Physical data for
some arene ligands and amination products and an ORTEP
drawing including the atomic coordinates, thermal parameters,
bond distances, bond angles, and thermal parameters for the
compound 12 (30 pages). This material is contained in
libraries on microfiche, immediately follows this article in the
microfilm version of the journal, and can be ordered from the
ACS; see any current masthead page for ordering information.
(()-Tr ip h en ylp h osp h in e(d ica r bon yl)[m eth yl r-(o-Di-
p h en ylp h osp h in op h en yl)eth yl Eth er ]ch r om iu m (8): mp
188 °C; 1H NMR (270 MHz, CDCl3) δ 1.28 (3 H, d, J ) 6.3
Hz), 2.80 (3 H, s), 4.31-4.64 (4 H, m), 4.98 (1 H, t, J ) 6.3
(18) Yamamoto, T.; Nishiyama, M.; Koie, Y. Tetrahedron Lett. 1998,
39, 2367-2370.
J O981327+