Rhodium-catalyzed asymmetric hydroarylation of 3-pyrrolines giving 3-arylpyrrolidines: Protonation as a key step

Article abstract of DOI:10.1021/ja406169s

A hydroxorhodium complex coordinated with (R)-segphos was found to catalyze the hydroarylation of 3-pyrrolines with arylboroxines under neutral conditions to give 3-arylpyrrolidines with high enantioselectivity in high yields.

Full text of DOI:10.1021/ja406169s

Communication
pubs.acs.org/JACS
Rhodium-Catalyzed Asymmetric Hydroarylation of 3‑Pyrrolines
Giving 3‑Arylpyrrolidines: Protonation as a Key Step
Chau Ming So,† Satoshi Kume,‡ and Tamio Hayashi*,†,‡,§
†Institute of Materials Research and Engineering, A*STAR, 3 Research Link, Singapore 117602, Singapore
‡Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan
§Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
S
* Supporting Information
Scheme 1. Rh-Catalyzed Asymmetric Alkene Hydroarylation
ABSTRACT: A hydroxorhodium complex coordinated
with (R)-segphos was found to catalyze the hydroarylation
of 3-pyrrolines with arylboroxines under neutral conditions
to give 3-arylpyrrolidines with high enantioselectivity in
high yields.
he Rh-catalyzed asymmetric arylation of alkenes with
Tarylboronic acids has offered one of the most convenient
and reliable methods of creating benzylic stereocenters with high
enantioselectivity.1 The reaction has been performed in protic
solvents, typically water or alcohols, to give hydroarylation
products. The alkenes successfully used for the hydroarylation
have been so far limited mainly to those activated by electron-
withdrawing substituents represented by carbonyl groups2−8
(Scheme 1a). In the hydroarylation of electron-deficient alkenes,
the catalytic cycle consists of (1) transmetalation of aryl group
from B to Rh to generate an arylrhodium species, (2) insertion of
the alkene into the aryl−Rh bond to form an alkylrhodium
species, and (3) protonation of the rhodium enolate-type
alkylrhodium intermediate in the reaction of carbonyl com-
pounds, to release the hydroarylation product.9 Kinetic studies
on the reaction of an α,β-unsaturated ketone demonstrated that
the protonation step is a fast step,10 and hence, the protonation
step does not compete against unfavorable reactions such as β-
hydrogen elimination in the Rh-catalyzed asymmetric reactions.
On the other hand, the asymmetric hydroarylation of alkenes has
not been successfully applied to those which lack the electron-
withdrawing groups, where the alkylrhodium intermediates are
reluctant to undergo the protonation to result in β-hydrogen
elimination to lead to olefinic products (Scheme 1b).11,12 In the
reactions of oxa- or azabicyclo[2.2.1]heptenes reported by
Murakami13 and Lautens,14 alkylrhodium intermediates, gen-
erated by arylrhodation, do not have syn β-hydrogens for β-
hydrogen elimination, and they undergo β-oxygen or β-nitrogen
elimination to form ring-opened olefinic products (Scheme
1c).15,16 In this context, we have been interested in the
asymmetric hydroarylation of 3-pyrrolines, which is challenging
because of the high possibility of side reactions such as β-
hydrogen and β-nitrogen eliminations (Scheme 1d). Another
reason for studying the addition to 3-pyrrolines is that the
enantiomerically enriched hydroarylation products, 3-arylpyrro-
lidines, are known to constitute an important subgroup of
compounds with pharmacologic acitvities.17,18
The reaction of N-(4-methoxybenzenesulfonyl)-3-pyrroline
(1a) with (PhBO)3 (2m) was carried out in the presence of
[RhCl(cod)]2 (5 mol % Rh, cod =1,5-cyclooctadiene) and KOH
(2.0 equiv to 1a) in 1,4-dioxane/H2O (10/1), which is one of the
best conditions in terms of catalytic activity for the Rh-catalyzed
conjugate addition of arylboronic acids to electron deficient
alkenes.19 The reaction at 60 °C for 16 h gave only 15% yield of
the desired hydrophenylation product 3am, major product being
arylated olefin 4am in 30% yield together with 15% of isomerized
olefin 5a (entry 1 in Table 1). Thus, the β-hydrogen elimination
Received: June 19, 2013
© XXXX American Chemical Society
A
dx.doi.org/10.1021/ja406169s | J. Am. Chem. Soc. XXXX, XXX, XXX−XXX

Journal of the American Chemical Society
Communication
a
Table 1. Rh-Catalyzed Hydrophenylation of 1a with 2m
Scheme 2. Rh-Catalyzed Reaction of 1a with 2m in THF/D2O
b
yield (%)
additive
(equiv)
T
c
entry
ligand
solvent
(°C)
3am
15
4am 5a
binap catalyst in THF/D2O at 60 °C (corresponding to entry 6 in
Table 1) was found to incorporate deuterium mainly (45% D) at
the ortho-position of 4-methoxybenzenesulfonyl group. The
second highest proportion of deuterium (42% D) was observed
at 5-position of the pyrrolidine ring, where the deuterium was all
located on the same side as the phenyl group. A minor amount of
deuterium (3% D) was also detected at the ortho-position of
phenyl group derived from phenylboroxine. It should be noted
that the 4-position of 3am is not substituted with deuterium at all.
On the basis of the deuterium incorporation studies, the
catalytic cycle producing 3am and 4am is proposed as shown in
Scheme 3. Phenylrhodium species B, generated by trans-
d
1
2
3
4
5
6
cod
KOH (2.0) dioxane
KOH (2.0) dioxane
KOH (0.1) dioxane
60
60
60
60
60
60
40
40
23
10
30
0
15
26
4
e
e
f
binap
binap
binap
7
30
0







dioxane
dioxane
THF
79 (84)
5
0
9
g
cod
1
8
f
f
binap
binap
81 (84)
88 (86)
95 (91)
93 (94)
54 (96)
0
14
7
h
7
THF
0
h
i
i
i
8
h
segphos
segphos
segphos
THF
0
4
9
THF
0
6
j
10
THF
0
2
a
Reaction conditions: 3-pyrroline 1a (0.25 mmol), (PhBO)3 2m (0.17
mmol for entries 1−2 and 0.42 mmol for other entries), Rh catalyst (5
mol % of Rh), dioxane/H2O or THF/H2O (1.0/0.1 mL) for 16 h.
Scheme 3. Reaction Pathway for 1a
b
c
Determined by 1H NMR of the reaction mixture. The enantiomeric
d
excess of 3am (%) is shown in parentheses. [RhCl(cod)]2.
e
f
g
[RhCl(C2H4)2]2/(R)-binap. [Rh(OH)(coe)2]2/(R)-binap. [Rh-
h
i
j
(OH)(cod)]2. For 24 h. [Rh(OH)(coe)2]2/(R)-segphos. For 36 h.
from an alkylrhodium intermediate is a predominant process
over protonation giving 3am under the conditions with a diene
ligand (vide infra for the catalytic pathway in detail). On the
other hand, the use of binap20 in place of cod as a ligand under
otherwise the same conditions gave hydrophenylation product
3am selectively albeit in a low yield (7%) (entry 2). The reaction
with a smaller amount (0.1 equiv to 1a) of KOH (entry 3), which
was performed in order to accelerate the protonation of an
alkylrhodium intermediate by making the reaction media less
basic, increased the reaction rate to give 3am in 30% yield. A
higher yield (79%) of 3am was obtained in the absence of KOH
9
by use of a hydroxo complex [Rh(OH)((R)-binap)2]2
21
generated from [Rh(OH)(coe)2]2 and (R)-binap (entry 4).
Attempts to further improve the yield of 3am by addition of
acidic proton sources such as carboxylic acids or phenol
derivatives failed; almost no hydrophenylation product was
observed. It is probably due to the deceleration of the
transmetalation step in acidic media.3b Interestingly, the reaction
catalyzed by the cod complex was not improved at all by use of
hydroxo rhodium complex, [Rh(OH)(cod)]2 (entry 5), which
has been also known to be an active catalyst for the addition to
several types of olefins and imines.10b The enantioselectivity in
giving (R)-3am was 84% ee with the (R)-binap-hydroxo catalyst
at the reaction temperature of 60 °C (entry 4), and the reaction
in THF/H2O gave a slightly higher yield of 3am than in dioxane/
H2O, in which the enantioselectivity was kept the same (entry 6).
By lowering the reaction temperature to 23 °C and using
segphos22 as a chiral ligand, the % ee of 3am was increased to
94% ee (entries 7−9). The selectivity was further increased to
96% ee at 10 °C, but the reaction was too slow to obtain a high
yield of the product in an acceptable reaction time (entry 10).
The hydrophenylation of 3-pyrroline 1a in D2O in place of
H2O (Scheme 2) gave us a significant insight into the catalytic
cycle which involves protonation as a key step. The product 3am
obtained in 75% yield by the reaction in the presence of hydroxo-
metalation of PhB(OH)2 to hydroxorhodium species A, adds
to 3-pyrroline 1a to generate alkylrhodium intermediate C,
which does not undergo protonation but undergoes β-hydrogen
elimination to form hydridorhodium−alkene complex D.
Dissociation of the olefin from D would give phenylated alkene
4am, which is a main product in the reaction catalyzed by Rh/cod
in the presence of KOH (entry 1 in Table 1). The phenylation
product 3am is formed in part (42%) by protonolysis of
alkylrhodium intermediate E which is generated by hydro-
rhodation on D with the regiochemistry opposite to that
returning to C. A major pathway (45%) to 3am is by way of
arylrhodium intermediate F which is generated by 1,5-shift of
Rh23 from 5-position of the pyrrolidine ring to ortho-position of
the arenesulfonyl group. The 1,4-Rh shift14c,24 from C to ortho-
phenyl intermediate G is not a main route (3%) leading to 3am.
Before the 1,4-shift, the alkylrhodium intermediate C immedi-
ately undergoes the β-hydrogen elimination to isomerize into E
which may be stabilized by the vicinal sulfonamide group. It is
B
dx.doi.org/10.1021/ja406169s | J. Am. Chem. Soc. XXXX, XXX, XXX−XXX

Journal of the American Chemical Society
Communication
remarkable that the protonation of alkylrhodium complex E was
demonstrated to take place with retention of configuration at the
sp3 carbon under the present conditions.25 The difference
between Rh/cod and Rh/binap catalyst systems is that the
olefinic product 4am is readily released from intermediate D in
the Rh/cod system while D is stable against its dissociation in the
Rh/binap system. As a result, the Rh intermediates are
isomerized into E and finally into aryl−rhodium species F in
part. They undergo the protonolysis under less basic conditions
to give a high yield of 3am.
Table 2. Rh-Catalyzed Asymmetric Hydroarylation of 3-
Pyrrolines 1 with Arylboroxines 2
a
The reaction in D2O shown in Scheme 2 was significantly
slower than the reaction in H2O. Thus, the relative reaction rate
kH2O/kD2O obtained by the reactions in two separate reaction
vessels was not smaller than 1.8.26 A competition reaction carried
out in the presence of a 1: 1 mixture of D2O and H2O gave the
product 3am where the deuterium incorporation is 11% at both 5
position of pyrrolidine and the ortho-position of the sulfonyl
group, indicating that the relative reactivity at the protonolysis is
kH/kD = 3. These deuterium kinetic isotope effects may well
demonstrate that the protonolysis step is a turnover-limiting
step.27
Under the optimized conditions found for the reaction of 3-
pyrroline 1a with phenylboroxine 2m (entry 9 in Table 1), the
[Rh(OH)(coe)2]2/(R)-segphos catalyst system was examined
for its scope in the asymmetric hydroarylation producing several
3-arylpyrrolidines 3. The results are summarized in Table 2.
Pyrrolines protected with sulfonamides substituted with p-tolyl
(1b), phenyl (1c), and 2-naphthyl (1d) groups gave the
corresponding hydrophenylation products with similar chemical
yield and enantioselectivity (entries 2−4) to the p-methox-
yphenyl-substituted one 1a (entry 1). Because of the easier
deprotection28 of 4-methoxybenzenesulfonyl group from nitro-
gen, the pyrrolidine 1a was used for the introduction of different
aryl groups (entries 5−18). In general, electronic effects of
arylboroxines are minimal in the present asymmetric hydro-
arylation. Electron neutral (2n−2q and 2y), electron rich (2r, 2s,
and 2z), and electron poor (2t−2x) aryl groups were successfully
introduced onto the pyrrolidine ring in high yields. The
enantioselectivity was kept high for all the substituted phenyl
groups.
b
c
entry
1
2
product 3
yield (%)
ee (%)
1
2
3
4
5
6
7
8
1a
1b
1c
1d
1a
1a
1a
1a
1a
1a
1a
1a
1a
1a
1a
1a
1a
1a
2m
2m
2m
2m
2n
2o
2p
2q
2r
3am
3bm
3cm
3dm
3an
3ao
3ap
3aq
3ar
91
91
90
87
92
97
96
95
87
95
80
97
96
82
82
92
99
95
94
93
93
93
93
95
93
93
94
91
89
92
92
92
85
94
95
96
d
9
10
2s
3as
e
11
2t
3at
12
13
14
15
16
17
2u
2v
2w
2x
3au
3av
3aw
3ax
3ay
3az
3az
2y
2z
d
18
2z
a
Reaction conditions: 3-pyrroline 1 (0.20 mmol), (Ar2BO)3 2 (0.42
mmol), [Rh(OH)(coe)2]2 (5.0 mol % of Rh), (R)-segphos (5.5 mol
b
%), THF/H2O (1.0/0.1 mL) at 23 °C for 24 h. Isolated yield.
c
d
e
Determined by HPLC on a chiral stationary phase. At 15 °C. With
10 mol % of the Rh catalyst at 40 °C.
The absolute configuration of hydrophenylation product 3bm
was determined to be R by comparison of its specific rotation
with that reported.17f In accordance with the highly skewed
structure known for segphos and binap complexes,2b,20,22 (R)-
segphos-Rh complex should have an open space at the lower part
of the olefin coordination site while the upper part is blocked by
one of the phenyl rings of segphos (Scheme 4). The
arylrhodation of the 3-pyrroline 1 at its coordination shown in
H, where the steric repulsions are minimized, gives the product 3
of R-configuration by way of the alkylrhodium intermediate I.
The 4-methoxybenzenesulfonyl group in 3am, 3at, and 3as
was readily removed without loss of their enantiomeric purities
by treatment with 48% hydrobromic acid and phenol28 (eq 1).
Scheme 4. Stereochemical Path To Form (R)-Pyrrolidine 3
The cleavage of methyl ether giving 3-(3-hydroxyphenyl)-
pyrrolidine (6s) took place for 3as under the reaction conditions.
The deprotected 3-arylpyrrolidines, 6m, 6t, and 6s, are all
known17 to be important compounds in pharmaceutical sciences.
Thus, the asymmetric hydroarylation of the 3-pyrrolines provides
an easy and efficient method of synthesizing a series of
compounds with potentially high biological activity.29
ASSOCIATED CONTENT
* Supporting Information
Procedures and characterization data. This material is available
free of charge via the Internet at http://pubs.acs.org.
■
S
C
dx.doi.org/10.1021/ja406169s | J. Am. Chem. Soc. XXXX, XXX, XXX−XXX

Journal of the American Chemical Society
Communication
(16) Murakami reported the asymmetric addition to but-2-ene-1,4-
diol, which gives an olefinic product resulting from β-hydroxy
elimination, see: Miura, T.; Takahashi, Y.; Murakami, M. Chem.
Commun. 2007, 595.
AUTHOR INFORMATION
■
Corresponding Author
tamioh@imre.a-star.edu.sg, chmtamh@nus.edu.sg
(17) For examples, see: (a) Alonso, B.; Ocejo, M.; Carrillo, L.; Vicario,
J. L.; Reyes, E.; Uria, U. J. Org. Chem. 2013, 78, 614. (b) Ahn, K. H.; Lee,
S. J.; Lee, C. H.; Hong, C. Y.; Park, T. K. Bioorg. Med. Chem. Lett. 1999, 9,
1379. (c) Deshpande, M. N.; Cain, M. H.; Patel, S. R.; Singam, P. R.;
Brown, D.; Gupta, A.; Barkalow, J.; Callen, G.; Patel, K.; Koops, R.;
Chorghade, M.; Foote, H.; Pariza, R. Org. Process Res. Dev. 1998, 2, 351.
(d) Feldman, P. L.; Brackeen, M. F.; Cowan, D. J.; Marron, B. E.;
Schoenen, F. J.; Stafford, J. A.; Suh, E. M.; Domanico, P. L.; Rose, D.;
Leesnitzer, M. A.; Brawley, E. S.; Strickland, A. B.; Verghese, M. W.;
Connolly, K. M.; Bateman-Fite, R.; Noel, J. S.; Sekut, L.; Stimpson, S. A.
J. Med. Chem. 1995, 38, 1505. (e) Yoshifuji, S.; Kaname, M. Chem.
Pharm. Bull. 1995, 43, 1302. (f) Denmark, S. E.; Marcin, L. R. J. Org.
Chem. 1995, 60, 3221. (g) Hackseell, U.; Arvidsson, L. E.; Svensson, U.;
Nilsson, L. G. J. Med. Chem. 1981, 24, 1475.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
Financial support from Institute of Materials Research and
Engineering is gratefully acknowledged.
REFERENCES
■
(1) For pertinent reviews, see: (a) Tian, P.; Dong, H.-Q.; Lin, G.-Q.
ACS Catal. 2012, 2, 95. (b) Partyka, D. V. Chem. Rev. 2011, 111, 1529.
(c) Berthon, G.; Hayashi, T. In Catalytic Asymmetric Conjugate Reactions;
́
Cordova, A., Ed.; Wiley-VCH: Weinheim, Germany, 2010; Chapter 1, p
(18) Rh-catalyzed asymmetric hydroarylation of maleimides and
fumaric esters has been applied to the asymmetric synthesis of 3-
arylpyrrolidines. For example, see: (a) Shintani, R.; Duan, W.-L.;
Nagano, T.; Okada, A.; Hayashi, T. Angew. Chem., Int. Ed. 2005, 44,
4611. (b) Piras, E.; Lang, F.; Ruegger, H.; Stein, D.; Worle, M.;
1. (d) Edwards, H. J.; Hargrave, J. D.; Penrose, S. D.; Frost, C. G. Chem.
Soc. Rev. 2010, 39, 2093. (e) Johnson, J. B.; Rovis, T. Angew. Chem., Int.
Ed. 2008, 47, 840. (f) Darses, S.; Genet, J.-P. Eur. J. Org. Chem. 2003,
4313. (g) Hayashi, T.; Yamasaki, K. Chem. Rev. 2003, 103, 2829.
(h) Fagnou, K.; Lautens, M. Chem. Rev. 2003, 103, 169. (i) Bolm, C.;
Grutzmacher, H. Chem.−Eur. J. 2006, 12, 5849. (c) Chung, Y.-C.;
̈
Hildebrand, J. P.; Muniz, K.; Hermanns, N. Angew. Chem., Int. Ed. 2001,
40, 3284.
(2) Addition to α,β-unsaturated ketones: (a) Sakai, M.; Hayashi, H.;
Miyaura, N. Organometallics 1997, 16, 4229. (b) Takaya, Y.; Ogasawara,
M.; Hayashi, T.; Sakai, M.; Miyaura, N. J. Am. Chem. Soc. 1998, 120,
5579.
̃
Janmanchi, D.; Wu, H.-L. Org. Lett. 2012, 14, 2766.
(19) Itooka, R.; Iguchi, Y.; Miyaura, N. J. Org. Chem. 2003, 68, 6000.
See also ref 8b.
(20) Takaya, H.; Mashima, K.; Koyano, K.; Yagi, M.; Kumobayashi, H.;
Taketomi, T.; Akutagawa, S.; Noyori, R. J. Org. Chem. 1986, 51, 629.
(21) [Rh(OH)(coe)2]2: Werner, H.; Bosch, M.; Schneider, M. E.;
(3) α,β-Unsaturated esters, amides, and aldehydes: (a) Takaya, Y.;
Senda, T.; Kurushima, H.; Ogasawara, M.; Hayashi, T. Tetrahedron:
Asymmetry 1999, 10, 4047. (b) Sakuma, S.; Sakai, M.; Itooka, R.;
Miyaura, N. J. Org. Chem. 2000, 65, 5951. (c) Senda, T.; Ogasawara, M.;
Hayashi, T. J. Org. Chem. 2001, 66, 6852. (d) Sakuma, S.; Miyaura, N. J.
Org. Chem. 2001, 66, 8944. (e) Paquin, J.-F.; Defieber, C.; Stephenson,
C. R. J.; Carreira, E. M. J. Am. Chem. Soc. 2005, 127, 10850.
(4) Alkenylphosphonates: Hayashi, T.; Senda, T.; Takaya, Y.;
Ogasawara, M. J. Am. Chem. Soc. 1999, 121, 11591.
(5) Nitroalkenes: Hayashi, T.; Senda, T.; Ogasawara, M. J. Am. Chem.
Soc. 2000, 122, 10716.
́
(6) Alkenylsulfones: (a) Mauleon, P.; Carretero, J. C. Org. Lett. 2004, 6,
3195. (b) Nishimura, T.; Takiguchi, Y.; Hayashi, T. J. Am. Chem. Soc.
2012, 134, 9086.
(7) Borylalkenes: Sasaki, K.; Hayashi, T. Angew. Chem., Int. Ed. 2010,
49, 8145.
(8) Alkenylheteroarenes and alkenylarenes: (a) Pattison, G.; Piraux,
G.; Lam, H. W. J. Am. Chem. Soc. 2010, 132, 14373. (b) Saxena, A.; Lam,
H. W. Chem. Sci. 2011, 2, 2326.
(9) Hayashi, T.; Takahashi, M.; Takaya, Y.; Ogasawara, M. J. Am. Chem.
Soc. 2002, 124, 5052.
(10) (a) Kina, A.; Iwamura, H.; Hayashi, T. J. Am. Chem. Soc. 2006,
128, 3904. (b) Kina, A.; Yasuhara, Y.; Nishimura, T.; Iwamura, H.;
Hayashi, T. Chem.−Asian J. 2006, 1, 707.
(11) For an example of the reaction which gives the β-hydrogen
elimination products, see: (a) Lautens, M.; Roy, A.; Fukuoka, K.;
Fagnou, K.; Martín-Matute, B. J. Am. Chem. Soc. 2001, 123, 5358. See
also: (b) Mori, A.; Danda, Y.; Fujii, T.; Hirabayashi, K.; Osakada, K. J.
Am. Chem. Soc. 2001, 123, 10774.
(12) For examples of the reactions where the protonation vs β-
hydrogen elimination is a key issue, see refs 6b and 8b.
(13) Murakami, M.; Igawa, H. Chem. Commun. 2002, 390.
(14) (a) Lautens, M.; Dockendorff, C.; Fagnou, K.; Malicki, A. Org.
Lett. 2002, 4, 1311. (b) Lautens, M.; Dockendorff, C. Org. Lett. 2003, 5,
3695. (c) Panteleev, J.; Menard, F.; Lautens, M. Adv. Synth. Catal. 2008,
350, 2893. (d) Tsui, G. C.; Tsoung, J.; Dougan, P.; Lautens, M. Org. Lett.
2012, 14, 5542.
Hahn, C.; Kukla, F.; Manger, M.; Windmuller, B.; Weberndorfer, B.;
Laubender, M. J. Chem. Soc., Dalton Trans. 1998, 3549.
(22) Saito, T.; Yokozawa, T.; Ishizaki, T.; Moroi, T.; Sayo, N.; Miura,
T.; Kumobayashi, H. Adv. Synth. Catal. 2001, 343, 264.
(23) As only one report for the 1,5-shift of Rh, see: (a) Tobisu, M.;
Hasegawa, J.; Kita, Y.; Kinuta, H.; Chatani, N. Chem. Commun. 2012, 48,
11437. For 1,5-Pd shift, see: (b) Mota, A. J.; Dedieu, A.; Bour, C.;
Suffert, J. J. Am. Chem. Soc. 2005, 127, 7171. (c) Bour, C.; Suffert, J. Org.
Lett. 2005, 7, 653.
̈
̈
(24) For a 1,4-Rh shift from an alkylrhodium intermediate to an
arylrhodium intermediate, see: (a) Oguma, K.; Miura, M.; Satoh, T.;
Nomura, M. J. Am. Chem. Soc. 2000, 122, 10464. (b) Matsuda, T.;
Shigeno, M.; Murakami, M. J. Am. Chem. Soc. 2007, 129, 12086.
(c) Seiser, T.; Roth, O. A.; Cramer, N. Angew. Chem., Int. Ed. 2009, 48,
6320. (d) Shigeno, M.; Yamamoto, T.; Murakami, M. Chem.−Eur. J.
2009, 15, 12929. (e) Seiser, T.; Cramer, N. Chem.−Eur. J. 2010, 16,
3383. (f) Seiser, T.; Cathomen, G.; Cramer, N. Synlett 2010, 1699.
(g) Seiser, T.; Cramer, N. Angew. Chem., Int. Ed. 2010, 49, 10163. See
also: (h) Tobisu, M.; Hyodo, I.; Onoe, M.; Chatani, M. Chem. Commun.
2008, 6013 For 1,4-Pd shift, see references cited in ref 23a.
(25) For example, retention of configuration at protonolysis has been
reported in the Ru-catalyzed hydrogenation: Tellers, D. M.;
McWilliams, J. C.; Humphrey, G.; Journet, M.; DiMichele, L.;
Hinksmon, J.; McKeown, A. E.; Rosner, T.; Sun, Y.; Tillyer, R. D. J.
Am. Chem. Soc. 2006, 128, 17063.
(26) The relative reaction rate was obtained by multiple sets of the
reactions stopped at low conversions (12−50% yield, 5−15 min).
(27) (a) Scott, V. J.; Labinger, J. A.; Bercaw, J. E. Organometallics 2011,
30, 4374. For a pertinent review, see: (b) Simmons, E. M.; Hartwig, J. F.
Angew. Chem., Int. Ed. 2012, 51, 3066.
(28) Snyder, H. R.; Heckert, R. E. J. Am. Chem. Soc. 1952, 74, 2006.
(29) Simple internal olefins (2-octene, cyclohexene) did not undergo
the hydrophenylation under the conditions of Table 1, entry 6.
(15) Lautens also reported an asymmetric hydroarylation scheme in
the reaction of bicyclo[2.2.1]heptane system: For examples, see ref 14c
and Menard, F.; Lautens, M. Angew. Chem., Int. Ed. 2008, 47, 2085.
D
dx.doi.org/10.1021/ja406169s | J. Am. Chem. Soc. XXXX, XXX, XXX−XXX