BULLETIN OF THE
Note
KOREAN CHEMICAL SOCIETY
afforded 2c:in80%yieldand 13%eebyR-7aand in75%yield
and 37% ee by S-7a, respectively (entries 15 and 16 in
Table 1). It is worth pointing that, even though the size of sub-
Acknowledgments. This work was supported by a National
Research Foundation of Korea (NRF) grant (2011–0016303
and 2009–0053318) funded by the Korea Government
(MSIP). Experiments at PAL (Pohang Accelerator Labora-
tory, beamline 2D, 2013-1st-2D-015) were supported in part
by MSIP and POSTECH.
7
strates and/or products exceeds the available aperture of the
channels of the catalyst crystals 7, the reaction proceeded une-
ventfully regardless of the size (Table S1 in the Supporting
Information). This implied that all reactions must be taking
8
,9
place on the crystal surface.
In conclusion, the catalytic asymmetric carbonyl-ene reac-
tion of substrate 1 by heterogeneous catalysts based on the
MOF has been studied. Throughout this study, the benefits
of utilizing MOF-based heterogeneous catalysts compared
to the conventional homogeneous system have been high-
lighted. In addition, it has been demonstrated that the
References
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unscrambled mixed catalysts such as (R)-3aH /Ti(O-iPr) /
2
2
(
R)-KUMOF-1 (R-7a) provided significantly improved
results. Furthermore, (S)-3aH /Ti(O-iPr) /(R)-KUMOF-1
2
2
(
S-7a)gaveeven betterresults. Theseexperimentswereunam-
biguously carried out; notably, there was no concern about the
scrambling of ligands, which cannot be excluded completely
during a homogeneous catalytic reaction. In addition, it has
been demonstrated thatmost catalytic reactions must be taking
place on the MOF crystal surface rather than at active sites
inside the crystals.
3
. (a) F. Gándara, B. Gomez-Lor, E. Gutiérrez-Puebla, M. Iglesias,
M. A. Monge, D. M. Proserpio, N. Snejko, Chem. Mater. 2008,
Experimental
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0, 72; (b) S.-H. Cho, B. Ma, S. T. Nguyen, J. T. Hupp, T. E.
Preparation of (S)-3aH /Ti(O-iPr) /(R)-KUMOF-1(S–7a).
Albrecht-Schmitt, Chem. Commun. 2006, 42, 2563.
4. K. S. Jeong, Y. B. Go, S. M. Shin, S. J. Lee, J. Kim, O. M. Yaghi,
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5. (a) M. L. Clarke, M. B. France, Tetrahedron 2008, 64, 9003; (b)
S. Sakane, K. Maruoka, H. Yamamoto, Tetrahedron 1986, 42,
2
2
A mixture of (R)-KUMOF-1 (24 mg, 0.063 mmol) and
i
Ti(O Pr)4 (0.3 mL, 1 M in dichloromethane 0.3 mmol)
ꢀ
in dichloromethane(1.5 mL) was stirred for 5 h at 25 C.
Ti/(R)-KUMOF-1wascollectedbycentrifugation, andwashed
five times with dichloromethane (1.5 mL). (S)-BINOL (3aH2)
2
203; (c) S. Sakane, K. Maruoka, H. Yamamoto, Tetrahedron
Lett. 1985, 26, 5535.
. (a) K. Mikami, M. Terada, T. Nakai, J. Am. Chem. Soc. 1990,
(0.60 ml, 8.00 mmol) was added to this suspension, the mix-
6
ture was stirred at room temperature for 5 h, and then the sus-
pension was collected by centrifugation. The mixture washed
1
12, 3949; (b) K. Mikami, M. Terada, T. Nakai, J. Am. Chem.
Soc. 1989, 111, 1940.
. 10 mol % of catalyst based on the number of catalytic site in the
MOF crystal was used.
1
0
five times with dichloromethane (1.5 mL).
Carbonyl-ene Reaction of 1 by (S)-7a. To a suspension of
S)-7a (12 mg, 0.029 mmol) in dichloromethane (1 mL) was
7
(
8. Considering the size of (R)-3aH , it is understandable that, once
2
added asolution of1a (50 mg, 0.29 mmol) indichloromethane
the titanium of shallow layers of MOF trapped (R)-3aH , further
2
ꢀ
penetration of other (R)-3aH molecules to reach Ti(IV) residing
(0.1 mL) at 0 C. The reaction mixture was shaken for 20 h at
2
deep inside MOF would be prevented. The shrinkage of free
this temperature. Then the supernatant was collected, and the
resultant crystalline materials were washed with dichloro-
methane. The collection of the supernatant was repeated
two more times. The combined organic layer was dried over
pathway of the channel by the residing of extra (R)-3aH was
2
visualized by two-photon fluorescence microscopy (TPM),
which will be discussed later. S. M. Shin, M. S. Lee, J. H.
Han, N. Jeong, Chem. Commun. 2014, 50, 289.
anhydrous MgSO and filtered, and then concentrated in
4
9
1
. Please refer the Supporting Information.
vacuo. The residue was purified by flash chromatography
by elution with 5% ethyl acetate in hexanes to give 2a
0. (a) S. Pandiaraju, G. Chen, A. Lough, A. K. Yudin, J. Am. Chem.
Soc. 2001, 123, 3850; (b) M. Chavarot, J. J. Byrne, P. Y. Cha-
vant, J. Pardillos-Guindet, Y. Vallée, Tetrahedron Asymmetry
1998, 9, 3889.
(
40 mg, 85% yield). The enatiomeric excess was determined
9
as 67 %ee after 2a was transformed into S1.
Bull. Korean Chem. Soc. 2015, Vol. 36, 1282–1284
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