Nickel(II)-dipyridylphosphine-catalyzed enantioselective hydrosilylation of ketones in air

Article abstract of DOI:10.1002/asia.201200512

Out of thin air: Catalytic amounts of nickel(II) salt and non-racemic dipyridylphosphine ligand, as well as the stoichiometric hydride source PhSiH₃, formed an effective catalyst system for the Ni ^II-catalyzed asymmetric hydrosilylat

Full text of DOI:10.1002/asia.201200512

DOI: 10.1002/asia.201200512
Nickel(II)-Dipyridylphosphine-Catalyzed Enantioselective Hydrosilylation of
Ketones in Air
Fei-Fei Wu,[a] Ji-Ning Zhou,[a] Qiang Fang,[a] Yi-Hu Hu,[a] Shijun Li,[a] Xi-Chang Zhang,[a]
Albert S. C. Chan,[b] and Jing Wu*[a]
Optically enriched secondary alcohols are highly valuable
intermediates in organic synthesis, especially when their sig-
nificance as chiral building blocks of numerous natural prod-
ucts, pharmaceuticals, and other biologically active mole-
cules is taken into account.[1] The non-noble-metal-catalyzed
enantioselective hydrosilylation of prochiral ketones repre-
sents a rewarding transformation towards chiral alcohols
owing to the economic benefits and the operational simplici-
ty of such methods.[2] Thus, in the past two decades, a variety
of effective chiral transition-metal catalysts based on titani-
um,[3] zinc,[4] tin,[5] copper,[6,7] iron,[8,9] and cobalt[10] have
been accordingly developed and applied in the asymmetric
hydrosilylation of ketones with good to excellent enantiose-
lectivities. Nickel-based catalysts have shown better activi-
ties in heterogeneous and some homogeneous reactions,
such as hydrogenation and cross-coupling reactions, than
other catalytic systems mediated by biologically relevant
metals, for example, Fe, Cu, or Zn.[11] Also, nickel catalyst
technology has played an important role in improving effi-
ciency in a number of industrial processes.[11a] To our knowl-
edge, although some achiral nickel catalysts have been ex-
ploited for the reduction of ketones,[12] there is no reported
analogous non-racemic catalyst involving nickel precursors.
Recently, we described the use of a family of atropisomer-
ic bipyridyldiphosphine ligands P-Phos (L1a, Table 1)[13] and
its variants (L1b Tol-P-Phos, L1c Xyl-Phos)[14] for effecting
the copper-mediated hydrosilylation of a diverse assortment
of ketones[7,15] as well as conjugate reduction of b-(acylami-
no)acrylates[16] under ambient conditions in competitive
levels of enantioselectivities and activities. Moreover, in the
presence of PhSiH3 as the hydride donor, the effectively
enantioselective reduction of alkyl aryl ketones was also re-
alized by using the cobalt(II)/Xyl-P-Phos catalyst system.[10c]
It is noteworthy that the aforementioned hydrosilylation sys-
tems were air-stable, which underlined their practical viabili-
ty and prompted us to investigate the catalytic properties of
NiH nonracemically ligated by P-Phos family ligands in the
relevant reduction reactions. Herein, we describe the first
example of nickel-catalyzed stereoselective hydrosilylation
of a selection of alkyl aryl ketones in air atmosphere in
moderate to good yields and enantioselectivities.
We commenced our studies by examining the effects of
various nickel precursors on the reduction of 4’-nitroaceto-
phenone (1a, Table 1). By utilizing 5 mol% anhydrous NiF2
and (S)-P-Phos ligand as well as two equivalents PhSiH3 as
the stoichiometric hydride source, the reaction proceeded in
toluene in air atmosphere at 458C to only 23% conversion
after 40 h to afford the desired alcohol (S)-2a in 79% ee
(Table 1, entry 1). Consistent with the results obtained from
our previous cobalt catalyst system,[10c] dramatic enhance-
ments in both conversion (99%) and enantioselectivity
(87% ee) were observed by adding 4 ꢀ MS (30 mg) to the
reaction mixture (0.2 mmol 1a; Table 1, entry 2 vs. entry 1).
Similar reaction outcomes were achieved in the case of Ni-
AHCTUNTGRENGUN(N OAc)2·4H2O, which is easy to handle and less expensive, as
a nickel source (Table 1, entry 3 vs. entry 2). Nonetheless,
17% and 77% conversions were obtained, respectively,
when the hydrosilylation of 0.2 mmol 1a was carried out in
the presence of 4 ꢀ MS (15 or 60 mg; Table 1, entries 4 and
5 vs. entry 3). In addition, other nickel(II) halides including
NiCl2, NiBr2 and NiI2 as well as [NiACHTNUTRGNEUNG(acac)2] (acac=acetyla-
cetonate) showed poor to moderate activities (1–61% conv.;
Table 1, entries 6–9 vs. entries 2 and 3). Moreover, as the
data in Table 1, entries 10 to 16 indicated, the reaction was
also strongly ligand-dependent. Among the various chiral di-
phosphine ligands screened, sterically more demanding li-
gands (S)-Tol-P-Phos (L1b, Table 1, entry 10) and (S)-Xyl-
P-Phos (L1c, Table 1, entry 11) possessed comparative
levels of activity and asymmetric induction with those of
parent ligand (S)-P-Phos (Table 1, entry 3) under otherwise
identical conditions. Moreover, when the reaction was con-
ducted in nitrogen, the reaction rate was lower than in air
(Table 1, entry 17 vs. entry 13). Finally, upon increasing the
catalyst loading to 10 mol%, full conversion and 90% ee
were attained at 308C by prolonging the reaction time to
64 h (Table 1, entry 18 vs. entry 3).
[a] F.-F. Wu, J.-N. Zhou, Q. Fang, Y.-H. Hu, S. Li, X.-C. Zhang,
Prof. Dr. J. Wu
College of Material, Chemistry and Chemical Engineering
Hangzhou Normal University, Hangzhou 310036 (China)
Fax : (+86)571-2886-8023
E-mail: jingwubc@hznu.edu.cn
[b] Prof. Dr. A. S. C. Chan
State Key Laboratory of Chiroscience and Institute of Creativity
Hong Kong Baptist University, Hong Kong
Further investigations demonstrated that both silanes and
solvents had pronounced influences on the reaction activi-
ties. For instance, by selecting Ph2SiH2, Ph3SiH, PMHS
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/asia.201200512.
Chem. Asian J. 2012, 00, 0 – 0
ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1
&
&
&
These are not the final page numbers! ÞÞ

COMMUNICATION
Table 1. Selected optimization of conditions for the nickel-catalyzed
Table 2. Nickel(II)-catalyzed asymmetric hydrosilylation of ketones using
(S)-Xyl-P-Phos in air.[a]
asymmetric hydrosilylation of 4’-nitroacetophenone 1a in air.[a]
Entry
Nickel salt
Ligand
Conv. [%][b]
ee [%][c]
Entry
Ketones
Nickel salt
Ni(OAc)2·4H2O
NiF2
Yield [%][b]
ee [%][c]
1[d]
2
NiF2
NiF2
L1a
L1a
L1a
L1a
L1a
L1a
L1a
L1a
L1a
L1b
L1c
L2
L3
L4
L5
L6
L3
L1a
23
99
98
17
77
61
3
<1
26
99
97
90
47
5
79
87
87
81
85
1
2
G
<5
<5
n.d.
n.d.
3[e]
4[f]
5[g]
6
Ni
Ni
Ni
N
3
4
Ni
N
<5
<5
n.d.
n.d.
NiF2
NiCl2
NiBr2
NiI2
80
7
8
9
n.d.[h]
n.d.
71
Ni
Ni
Ni
Ni
Ni
Ni
Ni
Ni
Ni
Ni
ACHTUNGTRENNUNG
5
Ni
N
91
87
71
80 (S)
82 (S)
73 (S)
10
11
12
13
14
15
16
17[i]
18[j]
A
84
88
34
76
23
2
15
77
N
N
6[d]
NiF2
R
N
G
3
7[d]
NiACTHNUTRGNE(NUG OAc)2·4H2O
T
10
18
99
T
A
90
[a] Reaction conditions: 33.0 mg substrate, substrate concentration 0.2m
in toluene; 30 mg 4 ꢀ MS added unless otherwise noted. [b] The conver-
sions were determined by NMR spectroscopy and GC analysis. [c] The ee
values were determined by chiral GC analysis. The absolute configura-
tion was determined by comparing the retention times with known data.
[d] The reaction was carried out in the absence of 4 ꢀ MS. [e] 68% con-
version and 86% ee were obtained in the presence of 1.2 equiv PhSiH3.
99% conversion and 88% ee were obtained in the presence of (R)-L1a.
[f] 15 mg 4 ꢀ MS were added. [g] 60 mg of 4 ꢀ MS were added. [h] n.d.=
not determined. [i] N2 atmosphere. [j] 10 mol% Ni salt and 10 mol%
ligand were used; reaction temperature 308C, reaction time 64 h, 95%
isolated yield.
8
NiF2
NiF2
34
42
71 (S)
61 (À)
9[d]
10[e]
Ni
N
97
87 (S)
11
12
NiF2
NiF2
78
68
86 (À)
67 (À)
[a] Substrate concentration 0.10–0.15m in toluene. [b] Yield of isolated
product. [c] The ee values were determined by chiral HPLC or GC analy-
sis. The absolute configuration was determined by comparing the reten-
tion times with known data. [d] The reduction of the functional groups
on the phenyl ring was not observed. [e] Reaction temperature 458C.
a selection of aryl alkyl ketones 1b–1k in air, and the repre-
sentative results of these studies are summarized in Table 2.
Our previous studies on the cobalt-catalyzed asymmetric hy-
drosilylation of aryl alky ketones indicated that the electron-
ic nature of the substituents on the phenyl ring of the keton-
ic substrates had a dramatic effect on the reaction activities,
and the substrates bearing an electron-withdrawing aryl
group reacted favorably to give higher yields and enantiose-
lectivities. Interestingly, a similar phenomenon was again ob-
served in the present nickel catalyst system. As illustrated in
Table 2, entries 1 to 4, under a given set of reaction condi-
tions, the reduction of either acetophenone (1b) or 4’-meth-
ylacetophenone (1c) was found to be rather sluggish (<5%
(poly(methyl hydrosiloxane)), (EtO)3SiH, or (EtO)2MeSiH
as the stoichiometric hydride donor, lower conversions or
almost no reaction were detected. Besides, toluene was
a much better solvent for the reaction than, for example,
CH2Cl2, 1,4-dioxane, THF, and CH3CN.
With the aforementioned preferred conditions in hand,
we set out to establish the general utility of this nickel-cata-
lyzed protocol for the enantioselective hydrosilylation of
yield) irrespective of the use of NiACHTNURGTNE(UNG OAc)2·4H2O or NiF2 as
&
&
&2
&
www.chemasianj.org
ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Asian J. 0000, 00, 0 – 0
ÝÝ These are not the final page numbers!

Nickel(II)-Catalyzed Enantioselective Hydrosilylation of Ketones
Germany, 2004; c) M. Breuer, K. Ditrich, T. Habicher, B. Hauer, M.
Kebeler, R. Stꢂrmer, T. Zelinski, Angew. Chem. 2004, 116, 806–843;
Angew. Chem. Int. Ed. 2004, 43, 788–824; d) V. Farina, J. T. Reeves,
C. H. Senanayake, J. J. Song, Chem. Rev. 2006, 106, 2734–2793.
[2] For comprehensive reviews, see: a) H. Nishiyama in Comprehensive
Asymmetric Catalysis I–III, (Eds.: E. N. Jacobsen, A. Pfaltz, H. Ya-
mamoto), Springer-Verlag, New York, 1999, Vol. 1, Chap. 6; b) H.
Nishiyama, K. Itoh in Catalytic Asymmetric Synthesis, 2nd ed. (Ed.:
I. Ojima), Wiley-VCH, New York, 2000, Chap. 2; c) H. Nishiyama,
K. Itoh in Transition Metals for Organic Synthesis, Vol. 2, 2nd ed.
(Eds.: M. Beller, C. Bolm), Wiley-VCH, Weinheim, 2004, pp. 182–
191; d) J. F. Carpentier, V. Bette, Curr. Org. Chem. 2002, 6, 913–
936; e) O. Riant, N. Mostefaꢃ, J. Courmarcel, Synthesis 2004, 2943–
2958; f) C. G. Arena, Mini-Rev. Org. Chem. 2009, 6, 159–167.
[3] Examples include: a) M. B. Carter, B. Schiott, A. Gutiꢄrrez, S. L.
Buchwald, J. Am. Chem. Soc. 1994, 116, 11667–11670; b) R. L. Hal-
terman, T. M. Ramsey, Z. Chen, J. Org. Chem. 1994, 59, 2642–2644;
c) S. Xin, J. F. Harrod, Can. J. Chem. 1995, 73, 999–1002; d) H.
Imma, M. Mori, T. Nakai, Synlett 1996, 1229–1230; e) M. Bandini,
P. G. Cozzi, L. Negro, A. Umani-Ronchi, Chem. Commun. 1999, 39–
40; f) J. Yun, S. L. Buchwald, J. Am. Chem. Soc. 1999, 121, 5640–
5644; g) P. Beagley, P. J. Davies, A. J. Blacker, C. White, Organome-
tallics 2002, 21, 5852–5858; h) M. Bandini, F. Bernardi, A. Bottoni,
P. G. Cozzi, G. P. Miscione, A. Umani-Ronchi, Eur. J. Org. Chem.
2003, 2972–2984.
the catalyst precursor. Whereas, transformation of aryl alkyl
ketones possessing electron-withdrawing substituents pro-
ceeded to provide the corresponding alcohols in 34–97%
yield and 61–87% ee (Table 2, entries 5–12). The exact role
of the electronic nature of the substituents on the phenyl
ring of the ketonic substrates for the reaction reactivities re-
mains unclear at this stage. It appeared that in the final step
of the catalytic cycle, the nickel alkoxide intermediate
[{(Ar)(R)C(H)O}NiL*ACTHNUGRTENUNG(OAc)] undergoes s-bond metathesis
À
À
with PhSiH3 between Ni O and Si H bonds to afford the
silyl ether and regenerate active species nickel hydride
[(AcO)NiHL*] (L*=(S)-1c). This is postulated to be the
rate limiting step, and the electron-withdrawing groups on
the nickel alkoxide might be favorable for the transmetala-
tion between nickel and silicon.[7f,17]
In addition, the outcomes of the reaction depended on
the positioning of the substituents on the arene ring of ke-
tones. Substrates with a para-substituted electron-deficient
aryl groups (1a, 1d–1 f) reacted favorably to afford the de-
sired alcohols with higher enantiopurity in better yields (73–
90% ee, 71–99% yield; Table 1, entry 17 and Table 2, en-
tries 5–7) when compared to the substrates with meta-substi-
tution (1g and 1h; Table 2, entries 8 and 9). Furthermore,
several other aryl alkyl ketones containing two or three
electron-withdrawing substituents (1i–1k) also underwent
effective and stereoselective hydrosilylation in air (Table 2,
entries 10–12).
In conclusion, with appropriate amounts of 4 ꢀ MS as ad-
ditives, the NiII-catalyzed stereoselective hydrosilylation of
a variety of electron-deficient aryl alkyl ketones was realiz-
ed for the first time in the presence of catalytic amounts of
nickel(II) salt and enantiomerically pure (S)-Xyl-P-Phos
ligand as well as the stoichiometric hydride source PhSiH3
with moderate to good enantioselectivities (up to 90% ee).
Noticeably, the reactions can be carried out in air atmos-
phere without special precautions, which highlights the prac-
tical potential of this protocol. Studies aimed at expanding
the scope of the present catalyst system and investigating
mechanistic features relevant to the above factors are under-
way in our laboratory.
[4] Examples include: a) H. Mimoun, J. V. de Saint Laumer, L. Gianni-
ni, R. Scopelliti, C. Floriani, J. Am. Chem. Soc. 1999, 121, 6158–
6166; b) V. M. Mastranzo, L. Quintero, C. A. de Parodi, E. Juaristi,
P. J. Walsh, Tetrahedron 2004, 60, 1781–1789; c) V. Bette, A. Mor-
treux, D. Svoia, J.-F. Carpentier, Tetrahedron 2004, 60, 2837–2842;
d) V. Bette, A. Mortreux, D. Savoia, J. F. Carpentier, Adv. Synth.
Catal. 2005, 347, 289–302; e) S. Gꢄrard, Y. Pressel, O. Riant, Tetra-
hedron: Asymmetry 2005, 16, 1889–1891; f) M. Bandini, M. Melucci,
F. Piccinelli, R. Sinisi, S. Tommasi, A. Umani-Ronchi, Chem.
´
Commun. 2007, 4519–4521; g) J. Gajewy, M. Kwit, J. Gawronski,
Adv. Synth. Catal. 2009, 351, 1055–1063; h) T. Inagaki, Y. Yamada,
L. T. Phong, A. Furuta, J.-i. Ito, H. Nishiyama, Synlett 2009, 253–
256; i) H. Ozasa, K. Kondo, T. Aoyama, Chem. Pharm. Bull. 2010,
58, 989–990; j) N. A. Marinos, S. Enthaler, M. Driess, ChemCatCh-
em 2010, 2, 846–853.
[5] N. Lawrence, S. M. Bushell, Tetrahedron Lett. 2000, 41, 4507–4512.
[6] For recent reviews, see: a) S. Rendler, M. Oestreich, Angew. Chem.
2007, 119, 504–510; Angew. Chem. Int. Ed. 2007, 46, 498–504; b) S.
Dꢅez-Gonzꢆlez, S. P. Nolan, Acc. Chem. Res. 2008, 41, 349–358;
c) C. Deutsch, N. Krause, B. H. Lipshutz, Chem. Rev. 2008, 108,
2916–2927; d) B. H. Lipshutz, Synlett 2009, 509–524; e) A. V.
Malkov, Angew. Chem. 2010, 122, 10008–10009; Angew. Chem. Int.
Ed. 2010, 49, 9814–9815 and references therein.
[7] Examples include: a) H. Brunner, W. Miehling, J. Organomet.
Chem. 1984, 275, C17–C21; b) B. H. Lipshutz, K. Noson, W. Chris-
man, J. Am. Chem. Soc. 2001, 123, 12917–12918; c) S. Sirol, J. Cour-
marcel, N. Mostefai, O. Riant, Org. Lett. 2001, 3, 4111–4113;
d) B. H. Lipshutz, A. Lower, K. Noson, Org. Lett. 2002, 4, 4045–
4048; e) B. H. Lipshutz, K. Noson, W. Chrisman, A. Lower, J. Am.
Chem. Soc. 2003, 125, 8779–8789; f) D.-W. Lee, J. Yun, Tetrahedron
Lett. 2004, 45, 5415–5417; g) J. Wu, J. X. Ji, A. S. C. Chan, Proc.
Natl. Acad. Sci. USA 2005, 102, 3570–3575; h) J. T. Issenhuth, S.
Dagorne, S. Bellemin-Laponnaz, Adv. Synth. Catal. 2006, 348, 1991–
1994; i) M. L. Kantam, S. Laha, J. Yadav, P. R. Likhar, B. Sreedhar,
S. Jha, S. Bhargava, M. Udayakiran, B. Jagadeesh, Org. Lett. 2008,
10, 2979–2982; j) C.-T. Lee, B. H. Lipshutz, Org. Lett. 2008, 10,
4187–4190; k) M. L. Kantam, J. Yadav, S. Laha, P. Srinivas, B.
Sreedhar, F. Figueras, J. Org. Chem. 2009, 74, 4608–4611; l) K.
Junge, B. Wendt, D. Addis, S. Zhou, S. Das, M. Beller, Chem. Eur. J.
2010, 16, 68–73; m) W. J. Li, S. X. Qiu, Adv. Synth. Catal. 2010, 352,
Acknowledgements
We thank the National Natural Science Foundation of China (21172049,
21032003, 91127010, 21072039), the Public Welfare Technology and Ap-
plication Program of Zhejiang Province (2010C31042) and the Special
Funds for Key Innovation Team of Zhejiang Province (2010R50017) for
generous financial support of this research.
Keywords: asymmetric catalysis · hydrosilylation · ketones ·
nickel · P ligands
ˇ
ˇ
´
1119–1122; n) R. Moser, Z. V. Boskovic, C. S. Crowe, B. H. Lip-
shutz, J. Am. Chem. Soc. 2010, 132, 7852–7853; o) X.-C. Zhang, F.-
F. Wu, S. Li, J.-N. Zhou, J. Wu, N. Li, W. Fang, K. H. Lam, A. S. C.
Chan, Adv. Synth. Catal. 2011, 353, 1457–1462; p) A. Albright,
[1] a) B. A. Astelford, L. O. Weigel in Chirality in Industry II (Eds.:
A. N. Collins), Wiley-VCH, New York, 1997, pp. 99–120; b) Asym-
metric Catalysis on Industrial Scale: Challenges, Approaches and Sol-
utions (Eds.: H.-U. Blaser, E. Schmidt), Wiley-VCH, Weinheim,
Chem. Asian J. 2012, 00, 0 – 0
ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemasianj.org
3
&
&
&
These are not the final page numbers! ÞÞ

Jing Wu et al.
COMMUNICATION
R. E. Gawley, J. Am. Chem. Soc. 2011, 133, 19680–19683; q) K. R.
Voigtritter, N. A. Isley, R. Moser, D. H. Aue, B. H. Lipshutz, Tetra-
hedron 2012, 68, 3410–3416.
[12] For representative examples of the hydrosilylation of ketones cata-
lyzed by achiral nickel complexes, see: a) S. Iyer, J. P. Varghese, J.
Chem. Soc., Chem. Commun. 1995, 465–466; b) F.-G. Fontaine, R.-
V. Nguyen, D. Zargarian, Can. J. Chem. 2003, 81, 1299–1306; c) T.
Irrgang, T. Schareina, R. Kempe, J. Mol. Catal. A, Chem. 2006, 257,
48–52; d) Y. K. Kong, J. Kim, S. Choi, S.-B. Choi, Tetrahedron Lett.
2007, 48, 2033–2036; e) S. Chakraborty, J. A. Krause, H. Guan, Or-
ganometallics 2009, 28, 582–886; f) B. L. Tran, M. Pink, D. J. Mind-
iola, Organometallics 2009, 28, 2234–2243.
[8] For recent reviews, see: a) S. Gaillard, J. L. Renaud, ChemSusChem
2008, 1, 505–509; b) R. H. Morris, Chem. Soc. Rev. 2009, 38, 2282–
2291; c) M. Zhang, A. Zhang, Appl. Organomet. Chem. 2010, 24,
751–757; d) K. Junge, K. Schrçder, M. Beller, Chem. Commun.
2011, 47, 4849–4859 and references therein.
[9] Examples include: a) H. Brunner, R. Eder, B. Hammer, U. Klement,
J. Organomet. Chem. 1990, 394, 555–567; b) H. Nishiyama, A.
Furuta, Chem. Commun. 2007, 760–762; c) N. Shaikh, S. Enthaler,
K. Junge, M. Beller, Angew. Chem. 2008, 120, 2531–2535; Angew.
Chem. Int. Ed. 2008, 47, 2497–2501; d) B. K. Langlotz, H. Wade-
pohl, L. H. Gade, Angew. Chem. 2008, 120, 4748–4752; Angew.
Chem. Int. Ed. 2008, 47, 4670–4674; e) A. M. Tondreau, J. M.
Darmon, B. M. Wile, S. K. Floyd, E. Lobkovsky, P. J. Chirik, Orga-
nometallics 2009, 28, 3928–3940; f) D. Addis, N. Shaikh, S. Zhou, S.
Das, K. Junge, M. Beller, Chem. Asian J. 2010, 5, 1687–1691; g) T.
Inagaki, A. Ito, J.-i. Ito, H. Nishiyama, Angew. Chem. 2010, 122,
9574–9577; Angew. Chem. Int. Ed. 2010, 49, 9384–9387; h) S. Hoso-
kawa, J.-i. Ito, H. Nishiyama, Organometallics 2010, 29, 5773–5775;
i) M. Flꢂckiger, A. Togni, Eur. J. Org. Chem. 2011, 4353–4360.
[10] a) H. Brunner, K. Amberger, J. Organomet. Chem. 1991, 417, C63–
C65; b) T. Inagaki, L. T. Phong, A. Furuta, J.-i. Ito, H. Nishiyama,
Chem. Eur. J. 2010, 16, 3090–3096; c) F. Yu, X.-C. Zhang, F.-F. Wu,
J.-N. Zhou, W. Fang, J. Wu, A. S. C. Chan, Org. Biomol. Chem. 2011,
9, 5652–5654.
[13] a) C.-C. Pai, C.-W. Lin, C.-C. Lin, C.-C. Chen, A. S. C. Chan, J. Am.
Chem. Soc. 2000, 122, 11513–11514; b) J. Wu, A. S. C. Chan, Acc.
Chem. Res. 2006, 39, 711–720.
[14] a) J. Wu, H. Chen, Z.-Y. Zhou, C.-H. Yeung, A. S. C. Chan, Synlett
2001, 1050–1054; b) J. Wu, H. Chen, W.-H. Kwok, K.-H. Lam, Z.-Y.
Zhou, C.-H. Yeung, A. S. C. Chan, Tetrahedron Lett. 2002, 43, 1539–
1543.
[15] a) X.-C. Zhang, Y. Wu, F. Yu, F.-F. Wu, J. Wu, A. S. C. Chan, Chem.
Eur. J. 2009, 15, 5888–5891; b) F. Yu, J.-N. Zhou, X.-C. Zhang, Y.-Z.
Sui, F.-F. Wu, L.-J. Xie, A. S. C. Chan, J. Wu, Chem. Eur. J. 2011, 17,
14234–14240; c) Y.-Z. Sui, X.-C. Zhang, J.-W. Wu, S. Li, J.-N. Zhou,
M. Li, W. Fang, A. S. C. Chan, J. Wu, Chem. Eur. J. 2012, 18, 7486–
7492.
[16] Y. Wu, S. Qi, F.-F. Wu, X.-C. Zhang, M. Li, J. Wu, A. S. C. Chan,
Org. Lett. 2011, 13, 1754–1757.
[17] a) T. Gathy, D. Peeters, T. Leyssens, J. Organomet. Chem. 2009, 694,
3943–3950; b) J.-T. Issenhuth, F.-P. Notter, S. Dagorne, A. Dedieu,
S. Bellemin-Laponnaz, Eur. J. Inorg. Chem. 2010, 529–541.
[11] Examples include: a) B. H. Lipshutz, Adv. Synth. Catal. 2001, 343,
313–326; b) C. Fischer, G. C. Fu, J. Am. Chem. Soc. 2005, 127,
4594–4595; c) Metal-Catalyzed Cross-Coupling Reactions, (Eds.: A.
de Meijere, F. Diederich), Wiley-VCH, New York, 2004.
Received: June 9, 2012
Revised: July 3, 2012
Published online: && &&, 0000
&
&
&4
&
www.chemasianj.org
ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Asian J. 0000, 00, 0 – 0
ÝÝ These are not the final page numbers!

COMMUNICATION
Out of thin air: Catalytic amounts of
nickel(II) salt and non-racemic dipyri-
dylphosphine ligand, as well as the sto-
ichiometric hydride source PhSiH3,
formed an effective catalyst system for
the NiII-catalyzed asymmetric hydrosi-
lylation of a diverse range of electron-
deficient aryl alkyl ketones with enan-
tioselectivities up to 90% ee. The prac-
tical potential of the protocol was
evinced by its good air-stability.
Asymmetric Catalysis
Fei-Fei Wu, Ji-Ning Zhou, Qiang Fang,
Yi-Hu Hu, Shijun Li, Xi-Chang Zhang,
Albert S. C. Chan, Jing Wu* &&&& — &&&&
Nickel(II)-Dipyridylphosphine-Cata-
lyzed Enantioselective Hydrosilylation
of Ketones in Air
Chem. Asian J. 2012, 00, 0 – 0
ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemasianj.org
5
&
&
&
These are not the final page numbers! ÞÞ