F. Sakurai et al. / Tetrahedron Letters 50 (2009) 6001–6003
6003
9. Yamamoto, Y.; Takizawa, M.; Yu, X.-Q.; Miyaura, N. Angew. Chem., Int. Ed. 2008,
47, 928–931.
10. Many ligands such as BINAP, Segphos, DIPAMP, DIOP, BPPM, and DPPFA
derivatives resulted in no reaction.
11. The use of 95%EtOH, DMF, DMSO, MeCN, toluene, 2-propanol or 1-butanol as a
solvent gave less satisfactory results.
In summary, in the Et-duphos-Ni-catalyzed asymmetric aryla-
tion, we utilized a Me2PhSi group as an ortho-substituent, which
led to good enantioselectivity (up to 99% ee). To our knowledge,
this is the first successful example of asymmetric Ni-catalyzed ary-
lation of aldehyde with a boron reagent. In the near future, we
hope that our developed method will be one of the candidates
for the synthesis of chiral diarylmethanols in addition to Shibasa-
ki’s method.14
12. The use of Na and Rb salts as an aryltriolborate gave less satisfactory results.
13.
g
2-Coordinated nickel complexes with aldehydes have been reported: (a)
Ogoshi, S.; Oka, M.; Kurosawa, H. J. Am. Chem. Soc. 2004, 126, 11802–11803; (b)
Ogoshi, S.; Kamada, H.; Kurosawa, H. Tetrahedron 2006, 62, 7583–7588.
14. Other spectral data were shown in Supplementary data except for the below.
Potassium
1-aryl-4-methyl-2,6,7-trioxa-1-boranuidabicyclo[2.2.2]octanes
were prepared according to the same procedure reported.9
Supplementary data
Preparation of ortho-dimethylphenylsilylbenzaldehyde (1b): To a stirred solution
of ortho-bromobenzaldehyde (3.0 mL 25.0 mmol) in EtOH (54 mL) was added
TsOHꢀH2O (905 mg 4.71 mmol) at rt. The reaction mixture was stirred for 21 h
under reflux, allowed to cool, quenched by the addition of NaHCO3 aq at 0 °C,
and directly evaporated. The residue was diluted with H2O and extracted with
EtOAc. The organic extracts were washed with brine, dried (Na2SO4), and
concentrated. These crude products (6.68 g) were used for the next step
without purification. To a stirred solution of the crude products (6.68 g) in Et2O
(20 mL) was gradually added BuLi (19.0 mL, 31.4 mmol 1.65 M in hexane) at
ꢁ78 °C. The reaction mixture was stirred for 1 h at ꢁ78 °C. To this solution was
gradually added Me2PhSiCl (5.2 mL 30.6 mmol), and then the whole mixture
was stirred for 0.5 h at ꢁ78 °C and additionally for 3 h at rt, quenched by the
addition of water, and extracted with EtOAc. The organic extracts were washed
with saturated NH4Cl aq and brine, dried (Na2SO4), and concentrated. These
crude products were used for the next step without purification. The solution of
the crude products and TsOHꢀH2O (991 mg 5.26 mmol) in acetone (100 mL) was
stirred for 1 h at rt, quenched by the addition of saturated NaHCO3 aq at 0 °C,
and directly evaporated. The residue was diluted with water and extracted with
EtOAc. The organic extracts were washed with brine, dried (Na2SO4), and
concentrated. Purification by SiO2 column (hexane/EtOAc = 30:1) afforded
ortho-dimethylphenylsilylbenzaldehyde (4.93 g, overall 82 %) as a colorless
Supplementary data associated with this article can be found, in
References and notes
1. Schmidt, F.; Stemmler, R. T.; Rudolph, J.; Bolm, C. Chem. Soc. Rev. 2006, 35, 454–
471.
2. (a) Tomita, D.; Wada, R.; Kanai, M.; Shibasaki, M. J. Am. Chem. Soc. 2005, 127,
4138–4139; (b) Tomita, D.; Kanai, M.; Shibasaki, M. Chem. Asian J. 2006, 1–2,
161–166.
3. Iminoalcohol-catalyed asymmetric arylation with the combination of
arylboronic acid and 7.2 equiv of Et2Zn: Bolm, C.; Rudolph, J. J. Am. Chem. Soc.
2002, 124, 14850–14851.
4. Miyaura’s group first reported that Rh(I) complexes catalyze the asymmetric
1,2-addition to 1-naphthaldehyde with phenylboronic acid, giving the
corresponding products in 41% ee: Sakai, M.; Ueda, M.; Miyaura, N. Angew.
Chem., Int. Ed. 1998, 37, 3279–3281; Quite recent successful example of Ru-
catalyzed asymmetric arylation with arylboronic acids: Yamamoto, Y.;
Kurihara, K.; Miyaura, N. Angew. Chem., Int. Ed. 2009, 48, 4414–4416.
5. For other Rh-catalyzed asymmetric arylations of aldehydes and activated
ketones with arylboron reagents, see: (a) Moreau, C.; Hague, C.; Weller, A. S.;
Frost, C. G. Tetrahedron Lett. 2001, 42, 6957–6960; (b) Focken, T.; Rudolph, J.;
Bolm, C. Synthesis 2005, 429–436; (c) Suzuki, K.; Ishii, S.; Kondo, K.; Aoyama, T.
Synlett 2006, 648–650; (d) Suzuki, K.; Kondo, K.; Aoyama, T. Synthesis 2006,
1360–1364; (e) Arao, T.; Sato, K.; Kondo, K.; Aoyama, T. Chem. Pharm. Bull.
2006, 54, 1576–1581; (f) Arao, T.; Suzuki, K.; Kondo, K.; Aoyama, T. Synthesis
2006, 3809–3814; (g) Shintani, R.; Inoue, M.; Hayashi, T. Angew. Chem., Int. Ed.
2006, 45, 3353–3356; (h) Duan, H.-F.; Xie, J.-H.; Shi, W.-J.; Zhang, Q.; Zhou, Q.-L.
Org. Lett. 2006, 8, 1479–1481; (i) Jagt, R. B. C.; Toullec, P. Y.; Schudde, E. P.; de
Vries, J. G.; Feringa, B. L.; Minnaard, A. J. J. Comb. Chem. 2007, 9, 407–414; (j)
Toullec, P. Y.; Jagt, R. B. C.; de Vries, J. G.; Feringa, B. L.; Minnaard, A. J. Org. Lett.
2006, 8, 2715–2718; (k) Duan, H.-F.; Xie, J.-H.; Qiao, X.-C.; Wang, L.-X.; Zhou,
Q.-L. Angew. Chem., Int. Ed. 2008, 47, 4351–4353; For Pd-catalyzed asymmetric
intramolecular arylations of ketones with arylboron substrate: (l) Liu, G.; Lu, X.
J. Am. Chem. Soc. 2006, 128, 16504–16505.
6. For recent contributions of Ni-catalyzed addition to aldehydes, see: (a)
Mahandru, G. M.; Liu, G.; Montgomery, J. J. Am. Chem. Soc. 2004, 126, 3698–
3699; (b) Miller, K. M.; Huang, W.-S.; Jamison, T. F. J. Am. Chem. Soc. 2003, 125,
3442–3443; (c) Saito, N.; Yamazaki, T.; Sato, Y. Tetrahedron Lett. 2008, 49,
5073–5076; (d) Sato, Y.; Takimoto, M.; Mori, M. J. Am. Chem. Soc. 2000, 122,
1624–1634.
7. (a) Arao, T.; Kondo, K.; Aoyama, T. Tetrahedron Lett. 2007, 48, 4115–4117; (b)
Yamamoto, K.; Tsurumi, K.; Sakurai, F.; Kondo, K.; Aoyama, T. Synthesis 2008,
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511–512.
oil. IR (neat): 1713 cmꢁ1 1H NMR (CDCl3): d = 0.63 (s, 6H), 7.30–7.35 (m, 3H),
.
7.48–7.65 (m, 5H), 7.89–7.92 (m, 1H), 10.04 (s, 1H). 13C NMR(CDCl3): d = ꢁ1.09,
127.70, 128.86, 129.60, 131.80, 132.87, 133.82, 136.58, 138.59, 140.62, 141.04,
192.74. FABMS: m/z = 241 (M++1). Anal. Calcd for C15H16OSi: C, 74.95; H, 6.71;
found: C, 74.55; H, 6.81.
Representative procedure for the asymmetric Ni-catalyzed arylation (Table 2,
entry 4): To a stirred solution of (R,R)-Et-duphos (11.1 mg, 0.0300 mmol) in
EtOH (0.6 mL) were added potassium 1-(3,5-dimethylphenyl)-4-methyl-2,6,7-
trioxa-1-boranuidabicyclo[2.2.2]octane (163 mg, 0.600 mmol), ortho-
dimethylphenylsilylbenzaldehyde (1b) (72.2 mg, 0.300 mmol), Ni(cod)2
(8.3 mg, 0.0300 mmol), and H2O (0.12 mL). The reaction mixture was stirred
for 20 h at 85 °C (oil bath temperature) and allowed to cool. After usual work-up,
purification by silica gel column (hexane/EtOAc = 20:1) afforded 3,5-
dimethylphenyl-2-dimethylphenylsilylphenylmethanol (95.9 mg, 92%) as
a
colorless oil. IR (neat):
m
= 3383 cmꢁ1 1H NMR(CDCl3): d = 0.63 (s, 3H), 0.67 (s,
.
3H), 1.74 (br s, 1H), 2.19 (s, 3Hꢂ2), 5.86 (s, 1H), 6.65 (s, 2H), 6.80 (s, 1H), 7.18–
7.34 (m, 6H), 7.51–7.63 (m, 3H). 13C NMR (CDCl3): d = ꢁ0.59, ꢁ0.49, 21.53, 74.45,
124.02, 127.13, 128.20, 128.50, 128.57, 129.35, 130.34, 133.99, 135.19, 136.59,
137.49, 139.37, 143.25, 149.92. EIMS: m/z = 329 (M+ꢁOH), 269 (M+ꢁPh), 253
(bp), 211 (M+ꢁSiMe2Ph). HRMS (M+ꢁPh): calcd for C17H21OSi: 269.12966;
found: 269.13618. Protodesilylation: The reaction mixture of 3,5-dimethyl-
phenyl-2-dimethylphenylsilylphenylmethanol (28.3 mg, 0.0820 mmol) and CsF
(24.8 mg, 0.163 mmol) in DMF/H2O (10:1, 0.55 mL) was stirred for 10 min under
reflux and allowed to cool. After usual work-up, purification by silica gel column
(hexane/EtOAc = 10:1) afforded 3,5-dimethylphenyl-phenylmethanol (17.4 mg,
100%, >99% ee) as a colorless oil. The ee was determined by HPLC analysis using
Daicel chiralpak IA. IR (neat): m .
= 3354 cmꢁ1 1H NMR (CDCl3): d = 2.17 (br d, 1H,
8. For recent successful examples of synthesis of chiral diarylmethanol or
diarylmethylamine with an ortho-substituted substrate, see: ortho-various
substituents: (a) Ohkuma, T.; Koizumi, M.; Ikehira, H.; Yokozawa, T.; Noyori, R.
Org. Lett. 2000, 2, 659–662; ortho-TMS group: (b) Kuriyama, M.; Soeta, T.; Hao,
X.; Chen, Q.; Tomioka, K. J. Am. Chem. Soc. 2004, 126, 8128–8129; orhto-Cl, Br,
and TMS groups: (c) Lee, C.-T.; Lipshutz, B. H. Org. Lett. 2008, 10, 4187–4190.
J = 2.6 Hz), 2.29 (s, 3Hꢂ2), 5.76 (s, 1H), 6.90 (s, 1H), 6.98 (s, 1H), 7.22–7.40 (m,
6H). 13C NMR (CDCl3): d = 21.43, 76.32, 124.21, 126.37, 127.34, 128.34, 129.16,
137.97, 143.65, 143.79. EIMS: m/z = 212 (M+), 107 (bp). HRMS (M+): calcd for
C15H16O: 212.12012; found: 212.11923.